General Description
The MAX15009 includes a 300mA LDO regulator, a
switched output, and an overvoltage protection (OVP)
controller to protect downstream circuits from high-volt-
age load dump. The MAX15011 includes only the 300mA
LDO regulator and switched output. Both devices operate
over a wide supply voltage range from 5V to 40V and are
able to withstand load-dump transients up to 45V. The
MAX15009/MAX15011 feature short-circuit and thermal-
shutdown protection. These devices offer highly integrat-
ed power management solutions for automotive
applications such as instrument clusters, climate control,
and a variety of automotive power-supply circuits.
The 300mA LDO regulator consumes 67µA quiescent
current at light loads and is well suited to power
always-on circuits during “key off” conditions. The LDO
features independent enable and hold inputs, as well
as a microprocessor (µP) reset output with adjustable
reset timeout period.
The switched output of the MAX15009/MAX15011
incorporates a low RDS(ON) (0.28Ω, typ) pass transistor
switch internally connected to the output of the LDO
regulator. This switch features accurate current-limit
sensing circuitry and is capable of controlling remote
loads. The MAX15009/MAX15011 feature an adjustable
current limit and a programmable delay timer to set the
overcurrent detection blanking time of the switch and
autoretry timeout.
The MAX15009 OVP controller operates with an external
enhancement mode n-channel MOSFET. While the moni-
tored voltage remains below the adjustable threshold, the
MOSFET stays on. When the monitored voltage exceeds
the OVP threshold, the OVP controller quickly turns off the
external MOSFET. The OVP controller is configurable as a
load-disconnect switch or a voltage limiter.
The MAX15009/MAX15011 are available in a thermally
enhanced, 32-pin (5mm x 5mm), TQFN package and are
fully specified over the -40°C to +125°C automotive oper-
ating temperature range.
Applications
Instrument Clusters
Climate Control
AM/FM Radio Power Supply
Multimedia Power Supply
Telematics Power Supply
Features
o300mA LDO Regulator, Switched Output, and OVP
Controller (MAX15009)
o300mA LDO Regulator and Switched Output
(MAX15011)
o5V to 40V Wide Operating Supply Voltage Range
o45V Load Dump Protection
o67µA Quiescent Current LDO Regulator
oOVP Controller Disconnects or Limits Output
Voltage During Battery Overvoltage Conditions
oLDO Regulator with Enable, Hold, and Reset
Features
oInternal 0.28Ω(typ) n-Channel Switch for
Switched Output
o100mA Switched Output with Adjustable Current-
Limit Blanking/Autoretry Delay
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
________________________________________________________________
Maxim Integrated Products
1
MAX15009
TQFN
(5mm x 5mm)
+
TOP VIEW
29
30
28
27
12
11
13
N.C.
N.C.
SGND
PGND
RESET
14
N.C.
OC_DELAY
OUT_LDO
IN
ILIM
IN
EN_PROT
12
OUT_SW
4567
2324 22 20 19 18
N.C.
N.C.
N.C.
SOURCE
GATE
N.C.
N.C. OUT_LDO
3
21
31 10
N.C. FB_PROT
32 9
N.C. CT
OUT_SW
26 15 FB_LDO
*EP
*EP = EXPOSED PAD
N.C.
25 16 EN_LDO
N.C. EN_SW
8
17
HOLD
Pin Configurations
19-0923; Rev 1; 2/08
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Typical Operating Circuits and Selector Guide appear at end
of data sheet. Pin Configurations continued at end of data sheet.
Ordering Information
+
Denotes a lead-free package.
For tape and reel, add a T after “+.”
*
EP = Exposed pad.
EVALUATION KIT
AVAILABLE
PART
TEMP RANGE
PIN-
PACKAGE
PKG
CODE
MAX15009ATJ+
-40°C to +125°C 32 TQFN-EP*
T3255-4
MAX15011ATJ+
-40°C to +125°C 32 TQFN-EP*
T3255-4
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF,
VOUT_LDO = 5V, CT= open, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
(All pins referenced to SGND, unless otherwise noted.)
IN, GATE.................................................................-0.3V to +45V
EN_LDO, EN_SW, EN_PROT ......................-0.3V to (VIN + 0.3V)
SOURCE ......................................................-0.3V to (VIN + 0.3V)
OUT_LDO, FB_LDO, FB_PROT, RESET,
OC_DELAY .........................................................-0.3V to +12V
GATE to SOURCE ..................................................-0.3V to +12V
OUT_SW, ILIM, HOLD ......................-0.3V to (VOUT_LDO + 0.3V)
OUT_SW to OUT_LDO ...........................................-12V to +0.3V
CT to SGND............................................................-0.3V to +12V
SGND to PGND .....................................................-0.3V to +0.3V
IN, OUT_LDO Current .......................................................700mA
OUT_SW Current...............................................................350mA
Current Sink/Source (all remaining pins) ............................50mA
Continuous Power Dissipation (TA= +70°C)
32-Pin TQFN (derate 34.5mW/°C above +70°C).............2.7W*
Thermal Resistance
θJA ..............................................................................29.0°C/W
θJC ................................................................................1.7°C/W
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
*
As per JEDEC 51 Standard, Multilayer Board (PCB).
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage Range V
IN
V
IN
≥ V
OUT
+ 1.5V 5 40 V
EN_LDO = IN, EN_SW =
EN_PROT = 0V, I
OUT_LDO
= 0µA, LDO on, switch off,
protector off, measured
from SGND
67 85
EN_LDO = EN_SW = IN,
EN_PROT = 0V, LDO ON,
I
OUT_LDO
= 100µA, switch
on, I
OUT_SW
= 0µA,
protector off, measured
from SGND
290 360
MAX15009
EN_LDO = EN_SW =
EN_PROT = IN, LDO ON,
I
OUT_LDO
= 100µA, switch
on, I
OUT_SW
= 0µA,
protector on, measured
from SGND
360 500
Supply Current I
IN
MAX15011
EN_LDO = EN_SW = IN,
LDO ON, I
OUT_LDO
=
100µA, switch on, I
OUT_SW
= 0µA, measured from
SGND
268 360
µA
T
A
= -40°C to
+85°C 16 30
Shutdown Supply Current I
SHDN
EN_LDO = EN_SW =
EN_PROT = SGND,
measured from
SGND
T
A
= -40°C to
+125°C 40
µA
IN Undervoltage Lockout V
UVLO
V
IN
falling, GATE disabled 4.10 4.27 4.45 V
IN Undervoltage Lockout
Hysteresis V
UVLO_HYST
260 mV
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
_______________________________________________________________________________________ 3
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Thermal-Shutdown
Temperature TSHDN +160 °C
Thermal Hysteresis THYST 20 °C
LDO
ILOAD = 1mA, FB_LDO = SGND 4.92 5.00 5.09
Output Voltage VOUT_LDO ILOAD = 300mA, VIN = 8V,
FB_LDO = SGND 4.88 5.00 5.11 V
FB_LDO Set-Point Voltage VFB_LDO With respect to SGND, ILOAD = 1mA,
VOUT_LDO = 5V, adjustable output option 1.21 1.235 1.26 V
FB_LDO rising 0.125
Dual Mode™ FB_LDO
Threshold VFB_LDO_TH FB_LDO falling 0.064 V
FB_LDO Input Current IFB_LDO VFB_LDO = 1V -100 +100 nA
LDO Output Voltage VLDO_ADJ Adjustable output option (Note 2) 1.8 11.0 V
ILOAD = 300mA (Note 3) 800 1500
LDO Dropout Voltage VDO ILOAD = 200mA (Note 3) 520 1000 mV
LDO Output Current IOUT_LDO (Note 4) 300 mA
LDO Output Current Limit ILIM_LDO OUT_LDO = SGND, VIN = 6V 330 500 700 mA
6V ≤ VIN ≤ 40V, ILOAD = 1mA,
VOUT_LDO = 5V 0.03 0.2
6V ≤ VIN ≤ 40V, ILOAD = 1mA,
FB_LDO = SGND, VOUT_LDO = 3.3V 0.03 0.1
6V ≤ VIN ≤ 40V, ILOAD = 20mA,
FB_LDO = SGND, VOUT_LDO = 5V 0.27 1
OUT_LDO Line Regulation ΔVOUT/
ΔVIN
6V ≤ VIN ≤ 40V, ILOAD = 20mA,
VOUT_LDO = 3.3V 0.27 0.5
mV/V
1mA to 300mA, VIN = 8V,
FB_LDO = SGND 0.054 0.15
OUT_LDO Load Regulation ΔVOUT/
ΔIOUT 1mA to 300mA, VIN = 6.3V,
VOUT_LDO = 3.3V 0.038 0.100
mV/mA
OUT_LDO Power-Supply
Rejection Ratio PSRR ILOAD = 10mA, f = 100Hz, 500mVP-P,
VOUT_LDO = 5V 60 dB
OUT_LDO Startup Delay
Time tSTARTUP_DELAY
IOUT_LDO = 0mA, from EN_LDO rising to
10% of VOUT_LDO (nominal),
FB_LDO = SGND
30 µs
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF,
VOUT_LDO = 5V, CT= open, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
Dual Mode is a trademark of Maxim Integrated Products, Inc.
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF,
VOUT_LDO = 5V, CT= open, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
OUT_LDO Overvoltage
Protection Threshold VOV_TH 1mA sink from OUT_LDO 105 110 %VOUT_LDO
OUT_LDO Overvoltage
Protection Sink Current IOV VOUT_LDO = VOUT (nominal) x 1.15 8 19 mA
ENABLE/HOLD INPUTS
VIH 2
EN_LDO to EN_PROT Input
Threshold Voltage VIL 0.7 V
E N _LD O, E N _P ROT, E N _S W
Input Pulldown Current IEN_PD EN_ is internally pulled low to SGND 1 µA
VIH 1.4
HOLD Input Threshold
Voltage VIL 0.4 V
HOLD Input Pullup IHOLD_PU
HOLD is internally pulled high to
OUT_LDO 0.6 µA
RESET
RESET goes HIGH when rising
VOUT_LDO crosses this threshold,
FB_LDO = SGND
90.0 92.5 95.0 %VOUT_LDO
RESET Voltage Threshold
HIGH V
R ESET_H
RESET goes HIGH when rising
VFB_LDO crosses this threshold 90.0 92.5 95.0 %VFB_LDO
RESET goes LOW when falling
VOUT_LDO crosses this threshold,
FB_LDO = SGND
88 90 92 %VOUT_LDO
RESET Voltage Threshold
LOW VRESET_L
RESET goes LOW when falling
VFB_LDO crosses this threshold 88 90 92 %VFB_LDO
VOUT_LDO to RESET Delay tRESET_FALL VOUT_LDO falling, 0.1V/µs 19 µs
CT Ramp Current ICT VCT = 0V 1.50 2 2.35 µA
CT Ramp Threshold VCT_TH VCT rising 1.190 1.235 1.270 V
RESET Output-Voltage Low VOL ISINK = 1mA, output asserted 0.1 V
RESET Open-Drain
Leakage Current ILEAK_RESET Output not asserted 150 nA
LOAD DUMP PROTECTOR (MAX15009 only)
FB_PROT Threshold
Voltage VTH_PROT FB_PROT rising 1.20 1.235 1.27 V
FB_PROT Threshold
Hysteresis VHYST 4%V
TH_PROT
FB_PROT Input Current IFB_PROT VFB_PROT = 1.4V -100 +100 nA
Startup Response Time tSTART EN_PROT rising, EN_LDO = IN, to
VGATE = 0.5V 20 µs
GATE Rise Time tGATE GATE rising to +8V, VSOURCE = 0V 1 ms
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF,
VOUT_LDO = 5V, CT= open, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
FB_PROT to GATE Turn-Off
Propagation Delay tOV FB_PROT rising from VTH_PROT -
250mV to VTH_PROT + 250mV 0.6 µs
VSOURCE = VIN = 5.5V,
RGATE to IN = 1MΩ
VIN +
3.2
VIN +
3.5
VIN +
3.8
GATE Output High Voltage VGATE - VIN VSOURCE = VIN; VIN ≥ 14V,
RGATE to IN = 1MΩ
VIN +
7.0
VIN +
8.1
VIN +
9.5
V
GATE Output Pulldown
Current IGATEPD VGATE = 5V, VEN_PROT = 0V 63 100 mA
GATE Charge-Pump
Current IGATE GATE = SGND 45 µA
GATE-to-SOURCE Clamp
Voltage VCLMP 12 16 18 V
SWITCH
Switch Dropout ΔVSW
ΔVSW = VOUT_LDO - VOUT_SW,
IOUT_SW = 100mA, VOUT_LDO = 5V,
no external MOSFET
36 70 mV
ILIM = OUT_LDO, VIN = 8V 170 200 240
RLIM = 100kΩ to SGND,
VOUT_LDO = 5V, VIN = 8V 85 100 120
Switch Current Limit ISW_LIM
RLIM = 39kΩ to SGND,
VOUT_LDO = 5V, VIN = 8V 30 40 50
mA
Current-Limit Selector ILIM
Voltage VILIM RLIM = 100kΩ0.395 V
OC_DELAY Timeout
Threshold VOC_DELAY 1.194 1.235 1.270 V
OC_DELAY Timeout Pullup
Current IOC_DELAY_UP VOC_DELAY = 0.5V rising 12.5 16.0 21.3 µA
OC_DELAY Timeout
Pulldown Current IOC_DELAY_DOWN VOC_DELAY = 0.5V, falling 0.75 1.00 1.40 µA
Minimum OC_DELAY
Timeout tOC_DELAY_MIN COC_DELAY is unconnected 12 µs
EN_SW to OUT_SW
Turn-On Time
OUT_SW rising to +0.5V,
ROUT_SW = 1kΩ38 µs
EN_SW to OUT_SW
Turn-Off Propagation Delay tOV_SW
EN_SW falling, VOUT_LDO - VOUT_SW
rising to +1V, ROUT_SW = 1kΩ,
VOUT_LDO = 5V
18 µs
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
Note 2: 1.8V is the minimum limit for proper HOLD functionality.
Note 3: Dropout is defined as VIN - VOUT_LDO when VOUT_LDO is 98% of the value of VOUT_LDO for VIN = VOUT_LDO + 1.5V.
Note 4: Maximum output current may be limited by the power dissipation of the package.
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
6 _______________________________________________________________________________________
Typical Operating Characteristics
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND,
TA= +25°C, unless otherwise specified.)
LDO GROUND CURRENT
vs. LOAD CURRENT
MAX15009 toc01
LOAD CURRENT (mA)
0 0.3 0.6 0.90.1 0.4 0.70.2 0.5 0.8 1.0
74
72
70
68
66
64
62
60
58
56
54
52
GROUND CURRENT (μA)
TA = -40°C
TA = +25°C
TA = +125°C
TA = +85°C
LDO GROUND CURRENT
vs. LOAD CURRENT
MAX15009 toc02
LOAD CURRENT (mA)
0 75 150 22525 100 17550 125 200 250 275 300
100
110
90
80
70
60
50
GROUND CURRENT (μA)
TA = -40°C
TA = +25°C
TA = +85°C
TA = +125°C
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX15009 toc03
TEMPERATURE (°C)
-60 0-40 1008060 120-20 20 40 140
30
25
35
20
15
10
5
0
ISHDN (μA)
LDO LOAD-TRANSIENT RESPONSE
MAX15009 toc09
400μs/div
IOUT_LDO
100mA/div
0A
VOUT_LDO
5V, AC-COUPLED
100mV/div
LDO POWER-SUPPLY
REJECTION RATIO vs. FREQUENCY
MAX15009 toc04
FREQUENCY (Hz)
10 100k10k100 1k 1M
-10
-20
0
-30
-40
-50
-60
-70
-80
-90
LDO PSRR (dB)
IOUT_LDO = 10mA
VIN UVLO HYSTERESIS
vs. TEMPERATURE
MAX15009 toc05
TEMPERATURE (°C)
-50 7525-25 125500 100 150
400
350
300
250
200
150
100
UVLO HYSTERESIS (mV)
LDO LOAD REGULATION
MAX15009 toc06
IOUT_LDO (mA)
0 200100 300
5.10
5.08
5.06
5.04
5.02
5.00
4.98
4.96
4.94
4.92
4.90
VOUT_LDO (V)
LDO OUTPUT VOLTAGE
vs. INPUT VOLTAGE
MAX15009 toc07
VIN (V)
025155352010 30 40
6
5
4
3
2
1
0
VOUT_LDO (V)
IOUT_LDO = 10mA
IOUT_LDO = 300mA
(PULSED)
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
_______________________________________________________________________________________
7
LDO OUTPUT VOLTAGE
vs. TEMPERATURE
MAX15009 toc10
TEMPERATURE (°C)
-50 7525-25 125500 100 150
5.10
5.05
5.00
4.95
4.90
4.85
4.80
VOUT_LDO (V)
IOUT_LDO = 10mA
IOUT_LDO = 100μA
IOUT_LDO = 100mA
VIN = 8V
IOUT_LDO = 300mA
SWITCH LOAD-TRANSIENT RESPONSE
MAX15009 toc11
400μs/div
VOUT_LDO
5V, AC-COUPLED
100mV/div
VOUT_SW
5V, AC-COUPLED
100mV/div
IOUT_SW
100mA/div 0A
IOUT_LDO = 100mA
IOUT_SW = 100mA
LINE-TRANSIENT RESPONSE
MAX15009 toc13
40ms/div
VOUT_LDO
3.3V, AC-COUPLED
20mV/div
VOUT_SW
3.3V, AC-COUPLED
20mV/div
VIN
10V/div
VOUT_PROT
10V/div
0V
0V
LDO DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX15009 toc14
IOUT_LDO (mA)
0 200100 300
1000
800
600
400
200
900
700
500
300
100
0
LDO DROPOUT VOLTAGE (mV)
LINE-TRANSIENT RESPONSE
MAX15009 toc12
40ms/div
VOUT_LDO
3.3V, AC-COUPLED
50mV/div
VOUT_SW
3.3V, AC-COUPLED
50mV/div
VIN
20V/div
VOUT_PROT
20V/div
0V
0V
SWITCH DROPOUT VOLTAGE
vs. TEMPERATURE
MAX15009 toc16
TEMPERATURE (°C)
-45 105 13053055-20 80
60
40
50
30
20
10
0
SWITCH DROPOUT VOLTAGE (mV)
IOUT_LDO = 10mA
IOUT_SW = 100mA
IOUT_SW = 10mA
SWITCH DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX15009 toc15
IOUT_SW (mA)
IOUT_LDO = 10mA
0 10050
40
30
20
10
35
25
15
5
0
SWITCH DROPOUT VOLTAGE (mV)
Typical Operating Characteristics (continued)
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND,
TA= +25°C, unless otherwise specified.)
STARTUP RESPONSE THROUGH V
IN
MAX15009 toc17
20ms/div
VIN
20V/div
0V
0V
0V
0V
VRESET
5V/div
VOUT_LDO
5V/div
VOUT_SW
5V/div
IOUT_LDO = 100mA
IOUT_SW = 70mA
EN_LDO = EN_SW = IN
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
8 _______________________________________________________________________________________
STARTUP RESPONSE THROUGH EN
MAX15008 toc18
20ms/div
IOUT_LDO = 100mA
IOUT_SW = 70mA
VEN_LDO = VEN_SW
VIN
VEN_LDO
5V/div
VRESET
5V/div
VOUT_LDO
5V/div
0V
0V
0V
0V
14V
VOUT_SW
5V/div
SHUTDOWN RESPONSE THROUGH V
IN
MAX15008 toc19
2ms/div
IOUT_LDO = 100mA
IOUT_SW = 70mA
EN_LDO = VEN_SW = IN
VIN
10V/div
VRESET
5V/div
VOUT_SW
5V/div
VOUT_LDO
5V/div
0V
0V
0V
0V
PROTECTOR STARTUP RESPONSE
MAX15009 toc25
10ms/div
VIN
10V/div
VGATE
10V/div
VOUT_PROT
10V/div
IOUT_PROT = 1A
0V
0V
0V
SHUTDOWN RESPONSE THROUGH EN
MAX15008 toc20
IOUT_LDO = 100mA
IOUT_SW = 70mA
EN_LDO = EN_SW
VOUT_SW
5V/div
VOUT_LDO
5V/div
VRESET
5V/div
VIN
20V/div 6V
0V
0V
0V
0V
VEN_LDO
5V/div
LDO, EN_LDO, AND HOLD TIMING
MAX15009 toc21
200ms/div
VEN_LDO
5V/div
VOUT_LDO
5V/div
HOLD
5V/div
RESET
5V/div 0V
0V
0V
0V
HOLD PULLED UP
TO OUT_LDO
GROUND CURRENT DISTRIBUTION
HISTOGRAM (TA = -40°C)
MAX15009 toc22
GROUND CURRENT (μA)
79 817775
737169
67
70
50
30
10
60
40
20
0
NUMBER OF PARTS
Typical Operating Characteristics (continued)
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND,
TA= +25°C, unless otherwise specified.)
PROTECTOR GATE VOLTAGE
vs. INPUT VOLTAGE (MAX15009 ONLY)
MAX15009 toc24
VIN (V)
20 2515 30 4010 3550
50
40
30
20
45
35
25
10
0
15
5
GATE VOLTAGE (V)
VGATE
VIN
GROUND CURRENT DISTRIBUTION
HISTOGRAM (TA = +125°C)
MAX15009 toc23
GROUND CURRENT (μA)
67 69 7165
6361
57 59
55
5351
90
40
30
20
10
80
70
60
50
0
NUMBER OF PARTS
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
_______________________________________________________________________________________
9
OVERVOLTAGE SWITCH FAULT
MAX15009 toc26
400μs/div
V
IN
10V/div
V
GATE
20V/div
V
OUT_PROT
20V/div
I
OUT_PROT
= 1A
V
OV
= 25V
0V
0V
0V
OVERVOLTAGE LIMIT FAULT
MAX15009 toc27
40ms/div
VIN
20V/div
VGATE
20V/div
VOUT_PROT
20V/div
IOUT_PROT = 1A
OV THRESHOLD = 35V
0V
0V
0V
Typical Operating Characteristics (continued)
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND,
TA= +25°C, unless otherwise specified.)
RESET TIMEOUT DELAY
vs. TEMPERATURE
MAX15009 toc29
TEMPERATURE (°C)
-25 250 100 12550 15075-50
0
0.6
1.2
1.8
0.4
1.0
1.6
0.2
0.8
1.4
2.0
RESET TIMEOUT DELAY (ms)
CRESET = 2.2nF
CRESET = 220pF
RESET TIMEOUT DELAY
vs. CRESET
MAX15009 toc28
CRESET (nF)
8621040
7
5
3
6
4
2
0
1
RESET TIMEOUT DELAY (ms)
SWITCH CURRENT LIMIT
vs. ILIM RESISTANCE
MAX15009 toc30
ILIM RESISTANCE (kΩ)
180120 140 1606040 100 2008020
20
60
120
180
40
100
160
80
140
200
SWITCH CURRENT LIMIT (mA)
TA = +125°C
TA = -40°C
TA = +25°C
TA = +85°C
INTERNAL PRESET SWITCH CURRENT LIMIT
vs. TEMPERATURE
MAX15009 toc31
TEMPERATURE (°C)
-25 25 500 125100 15075-50
150
180
210
240
170
160
200
230
190
220
250
PRESET CURRENT LIMIT (mA)
IOC_DELAY_UP AND IOC_DELAY_DOWN
vs. TEMPERATURE
MAX15009 toc32
TEMPERATURE (°C)
-25 25 500 125100 15075-50
0
6
12
4
2
10
16
8
14
18
OC_DELAY PULLUP/PULLDOWN CURRENT (μA)
IOC_DELAY_DOWN
IOC_DELAY_UP
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
10 ______________________________________________________________________________________
Pin Description
NAME
PIN MAX15009 MAX15011 FUNCTION
1–4, 8, 11,
14, 26, 29–32 N.C. —
1–4, 8,
10–14, 18,
26, 29–32
— N.C.
No Connection. Not internally connected.
5 SGND SGND Signal Ground
6 PGND PGND
Ground. PGND is also the return path for the overvoltage protector pulldown current
for the MAX15009. In this case, connect PGND to SGND at the negative terminal of the
bypass capacitor connected to the source of the external MOSFET. For the
MAX15011, connect PGND to SGND together to the local ground plane.
7RESET RESET
Active-Low Open-Drain Reset Output. RESET is low while OUT_LDO is below the reset
threshold. Once OUT_LDO has exceeded the reset threshold, RESET remains low for
the duration of the reset timeout period then goes high.
9CTCT
Reset Timeout Adjust Input. Connect a capacitor (CRESET) from CT to ground to adjust
the reset timeout period. See the Setting the
RESET
Timeout Period section.
10 FB_PROT —
Overvoltage-Threshold Adjustment Input. Connect FB_PROT to an external resistive
voltage-divider network to adjust the desired overvoltage threshold. Use FB_PROT to
monitor a system input or output voltage. See the Setting the Overvoltage Threshold
(MAX15009 Only) section.
12 GATE —
Protector Gate Drive Output. Connect GATE to the gate of an external n-channel
MOSFET. GATE is the output of a charge pump with a 45µA pullup current to 8.1V
(typ) above IN during normal operation. GATE is quickly turned off through a 63mA
internal pulldown during an overvoltage condition. GATE then remains low until
FB_PROT has decreased below 96% of the overvoltage threshold. GATE pulls low
when EN_PROT is low.
13 SOURCE —Output-Voltage Sense Input. Connect SOURCE to the source of the external n-channel
MOSFET.
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
______________________________________________________________________________________ 11
Pin Description (continued)
NAME
PIN MAX15009 MAX15011 FUNCTION
15 FB_LDO FB_LDO
LDO Voltage Feedback Input. Connect FB_LDO to SGND to select the preset +5V
output voltage. Connect FB_LDO to an external resistive voltage-divider for adjustable
output operation. See the Setting the Output Voltage section.
16 EN_LDO EN_LDO
Active-High LDO Enable Input. Connect EN_LDO to IN or to a logic-high voltage to
turn on the regulator. To place the LDO in shutdown, pull EN_LDO low or leave
unconnected and leave HOLD unconnected. EN_LDO is internally pulled to SGND
through a 1µA current sink. See the Control Logic section.
17 EN_SW EN_SW
Active-High Switch Enable Input. Connect EN_SW to IN or to a logic-high voltage to
turn on the switch. Pull EN_SW low or leave unconnected to place the switch in
shutdown. EN_SW is internally pulled to SGND through a 1µA current sink.
18 EN_PROT —
Protector Enable Input. Drive EN_PROT low to force GATE low and turn off the external
n-channel MOSFET. EN_PROT is internally pulled to SGND by a 1µA sink current.
Connect EN_PROT to IN for normal operation.
19, 20 IN IN Regulator Input. Bypass IN to SGND with a 10µF capacitor with an ESR < 1.5Ω.
21, 22 OUT_LDO OUT_LDO
LDO Regulator Output. Bypass OUT_LDO to SGND with a ceramic capacitor with a
minimum value of 22µF. OUT_LDO has a fixed 5V output or can be adjusted from1.8V
to 11V. See the Setting the Output Voltage section.
23 OC_DELAY OC_DELAY
Switch Overcurrent Blanking Time Programming Input. Leave OC_DELAY
unconnected to select the minimum delay timeout before turning the switch off.
OC_DELAY is internally pulled to SGND through a 1µA current source. See the
Programming the Switch Overcurrent Blanking Time section.
24 ILIM ILIM
Switch Current-Limit Set Input. Connect a 10kΩ to 200kΩ resistor from ILIM to SGND to
select the current limit for the internal switch. Connect ILIM to OUT_LDO to select the
internal 170mA (min) current-limit threshold. Do not leave ILIM unconnected. See the
Setting the Switch Current Limit section.
25 HOLD HOLD
Active-Low Hold Input. If EN_LDO is high when HOLD is forced low, the regulator
latches the state of the EN_LDO input and allows the regulator to remain turned on
when EN_LDO is subsequently pulled low. To shut down the regulator, release HOLD
after EN_LDO is pulled low. If HOLD functionality is unused, connect HOLD to
OUT_LDO or leave unconnected. HOLD is internally pulled up to OUT_LDO through a
0.6µA current source. See the Control Logic section.
27, 28 OUT_SW OUT_SW Switch Output. Bypass OUT_SW to SGND with a minimum 0.1µF ceramic capacitor.
—EPEP
Exposed Pad. Connect EP to SGND plane. EP also functions as a heatsink to maximize
thermal dissipation. Do not use as the main ground connection.
MAX15009/MAX15011
Functional Diagram
BIAS AND VOLTAGE
REFERENCE
CONTROL
LOGIC
VREF 1.235V
OUT_LDO
FB_LDO
CT
OUT_SW
OUT_LDO
RESET
GATE
VIN
SOURCE
M
U
X
0.124V
5V LDO
OUTPUT
PROTECTOR
OUTPUT
RESET
OUTPUT
IN LDO
IN
VIN
EN_PROT
EP SGND PGND
ENABLE
PROTECTOR
EN_LDO
ENABLE LDO
EN_SW
OC_DELAY
ENABLE SWITCH
HOLD
HOLD
2μA
0.925 x VREF
4.75V
IN
GATE UVLO
VGATE
VREF
VREF
ILIM
16μA
OUT_SW
SWITCH
1μA
VREF
S
R
Q
0.1V
OVERVOLTAGE PROTECTOR
(MAX15009 ONLY)
SWITCH
OUTPUT
FB_PROT
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
12 ______________________________________________________________________________________
Detailed Description
The MAX15009/MAX15011 integrate a 300mA LDO
voltage regulator, a current-limited switched output,
and an OVP controller (MAX15009 only). These devices
operate over a wide supply voltage range from 5V to
40V and are able to withstand load-dump transients up
to 45V.
The MAX15009/MAX15011 feature a 300mA LDO regu-
lator that consumes 70µA of current under light-load
conditions and feature a fixed 5V or an adjustable out-
put voltage (1.8V to 11V). Connect FB_LDO to ground
to select a fixed 5V output voltage or select the LDO
output voltage by connecting an external resistive volt-
age-divider at FB_LDO. The regulator sources at least
300mA of current and includes a current limit of 330mA
(min). Enable the LDO by pulling EN_LDO high.
The switch features accurate current-limit sensing cir-
cuitry and is capable of controlling remote loads. Once
enabled, an internal charge pump generates the over-
drive voltage for an internal MOSFET. The switch then
starts to conduct and OUT_SW is charged up to
VOUT_LDO. The switch is enabled when the output volt-
age of the LDO is above the RESET threshold voltage
(92.5% of the LDO nominal output value).
An overcurrent condition exists when the current at
OUT_SW, IOUT_SW, exceeds the 200mA (typ) internal
factory-set current-limit threshold or the externally
adjustable current-limit threshold. During a continuous
overcurrent event, the capacitor connected at
OC_DELAY, COC_DELAY, is charged up to a voltage of
1.235V with a current, IOC_DELAY_UP. When this voltage
is reached, an overcurrent latch is set and the gate of
the internal MOSFET is discharged, reducing IOUT_SW.
COC_DELAY is then discharged through a pulldown cur-
rent, IOC_DELAY_DOWN (IOC_DELAY_UP / 16) and the
internal MOSFET remains off until COC_DELAY has been
discharged to 0.1V. After this user-programmable turn-
off delay, the switch turns back on. This charge/
discharge is repeated if the overcurrent condition per-
sists. The switch returns to normal operation once the
overcurrent condition has been removed.
The OVP controller (MAX15009 only) relies on an exter-
nal MOSFET with adequate voltage rating (VDSS) to
protect downstream circuitry from overvoltage tran-
sients. The OVP controller drives the gate of the exter-
nal n-channel MOSFET, and is configurable to operate
as an overvoltage protection switch or as a closed-loop
voltage limiter.
GATE Voltage (MAX15009 Only)
The MAX15009 uses a high-efficiency charge pump to
generate the GATE voltage for the external n-channel
MOSFET. Once the input voltage, VIN, exceeds the
undervoltage lockout (UVLO) threshold, the internal
charge pump fully enhances the external n-channel
MOSFET. An overvoltage condition occurs when the
voltage at FB_PROT goes above the threshold voltage,
VTH_PROT. After VTH_PROT is exceeded, GATE is quick-
ly pulled to PGND with a 63mA pulldown current. The
MAX15009 includes an internal clamp from GATE to
SOURCE that ensures that the voltage at GATE never
exceeds one diode drop below SOURCE during gate
discharge. The voltage clamp also prevents the GATE-
to-SOURCE voltage from exceeding the absolute maxi-
mum rating for the VGS of the external MOSFET in case
the source terminal is accidentally shorted to 0V.
Overvoltage Monitoring (MAX15009 Only)
The OVP controller monitors the voltage at FB_PROT
and controls an external n-channel MOSFET, isolating,
or limiting the load during an overvoltage condition.
Operation in OVP switch mode or limiter mode
depends on the connection between FB_PROT and the
external MOSFET.
Overvoltage Switch Mode
When operating in OVP switch mode, the FB_PROT
divider is connected to the drain of the external MOS-
FET. The feedback path consists of the voltage-divider
tapped at FB_PROT, FB_PROT’s internal comparator,
the internal gate charge pump/gate pulldown, and the
external n-channel MOSFET (Figure 1). When the pro-
grammed overvoltage threshold is exceeded, the inter-
nal comparator quickly pulls GATE to ground and turns
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
______________________________________________________________________________________ 13
IN
VIN
FB_PROT
SGND
GATE
SOURCE
PROTECTOR
OUTPUT
MAX15009
Figure 1. Overvoltage-Limiter Switch Configuration (MAX15009)
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
14 ______________________________________________________________________________________
off the external MOSFET, disconnecting the power
source from the load. In this configuration, the voltage
at the source of the MOSFET is not monitored. When
the voltage at FB_PROT decreases below the overvolt-
age threshold, the MAX15009 raises the voltage at
GATE, reconnecting the load to the power source.
Overvoltage-Limiter Mode (MAX15009 Only)
When operating in overvoltage-limiter mode, the feed-
back path consists of SOURCE, FB_PROT’s internal
comparator, the internal gate charge pump/gate pull-
down, and the external n-channel MOSFET (Figure 2).
This configuration results in the external MOSFET oper-
ating as a hysteretic voltage regulator.
During normal operation, GATE is enhanced 8.1V above
VIN. The external MOSFET source voltage is monitored
through a resistive voltage-divider between SOURCE
and FB_PROT. When VSOURCE exceeds the adjustable
overvoltage threshold, an internal pulldown switch
discharges the gate voltage and quickly turns the
MOSFET off. Consequently, the source voltage begins
to fall. The VSOURCE fall time is dependent on the MOS-
FET’s gate charge, the internal charge-pump current,
the output load, and any load capacitance at SOURCE.
When the voltage at FB_PROT is below the overvoltage
threshold by an amount equal to the hysteresis, the
charge pump restarts and turns the MOSFET back on.
In this way, the OVP controller attempts to regulate
VSOURCE around the overvoltage threshold. SOURCE
remains high during overvoltage transients and the
MOSFET continues to conduct during an overvoltage
event. The hysteresis of the FB_PROT comparator and
the gate turn-on delay force the external MOSFET to
operate in a switched on/off sequence during an over-
voltage event.
Exercise caution when operating the MAX15009 in volt-
age-limiting mode for long durations. Care must be
taken against prolonged or repeated exposure to over-
voltage events while delivering large amounts of load
current as the power dissipation in the external MOS-
FET may be high under these conditions. To prevent
damage to the MOSFET, implement proper heatsinking.
The capacitor tied between SOURCE and ground may
also be damaged if the ripple current rating for the
capacitor is exceeded.
As the transient voltage decreases, the voltage at
SOURCE falls. For fast-rising transients and very large
MOSFETs, connect an additional capacitor from GATE
to PGND. This capacitor acts as a voltage-divider work-
ing against the MOSFET’s drain-to-gate capacitance. If
using a very low gate charge MOSFET, additional
capacitance from GATE to ground might be required to
reduce the switching frequency.
Control Logic
The MAX15009/MAX15011 LDO features two logic
inputs, EN_LDO and HOLD, making these devices suit-
able for automotive applications. For example, when
the ignition key signal drives EN_LDO high, the regula-
tor turns on and remains on even if EN_LDO goes low,
as long as HOLD is forced low and stays low after initial
regulator power-up. In this state, releasing HOLD turns
the regulator output (OUT_LDO) off. This feature makes
it possible to implement a self-holding circuit without
external components. Forcing EN_LDO low and HOLD
high (or unconnected) places the regulator into shut-
down mode, reducing the supply current to less than
16µA. Table 1 shows the state of OUT_LDO with
respect to EN_LDO and HOLD. Leave HOLD uncon-
nected or connect directly to OUT_LDO to allow the
EN_LDO input to act as a standard on/off logic input for
the regulator.
IN
VIN
FB_PROT
SGND
GATE
SOURCE
PROTECTOR
OUTPUT
MAX15009
Figure 2. Overvoltage Limiter (MAX15009)
Applications Information
Load Dump
Most automotive applications run off a multicell 12V
lead-acid battery with a nominal voltage that swings
between 9V and 16V, depending on load current,
charging status, temperature, and battery age, etc. The
battery voltage is distributed throughout the automobile
and is locally regulated down to voltages required by
the different system modules. Load dump occurs when
the alternator is charging the battery and the battery
becomes disconnected. Power in the alternator (behav-
ing now essentially as an inductor) flows into the dis-
tributed power system and elevates the voltage seen at
each module. The voltage spikes have rise times typi-
cally greater than 5ms and decay within several hun-
dred milliseconds but can extend out to 1s or more
depending on the characteristics of the charging sys-
tem. These transients are capable of destroying semi-
conductors on the first fault event.
The MAX15009/MAX15011 feature load-dump transient
protection up to +45V.
Setting the Output Voltage
The MAX15009/MAX15011 feature dual-mode opera-
tion: these devices operate in either a preset voltage
mode or an adjustable mode. In preset voltage mode,
internal feedback resistors set the linear regulator out-
put voltage (VOUT_LDO) to 5V. To select the preset 5V
output voltage, connect FB_LDO to SGND.
To select an adjustable output voltage between 1.8V
and 11V, use two external resistors connected as a
voltage-divider to FB_LDO (Figure 3). Set the output
voltage using the following equation:
VOUT_LDO = VFB_LDO x (R1+ R2) / R2
where VFB_LDO = 1.235V and R2≤50kΩ.
Setting the
RESET
Timeout Period
The reset timeout period is adjustable to accommodate
a variety of applications. Set the reset timeout period by
connecting a capacitor, CRESET, between CT and
SGND. Use the following formula to select the reset
timeout period, tRESET:
tRESET = CRESET x VCT_TH / ICT
where tRESET is in seconds and CRESET is in µF.
VCT_TH is the CT ramp threshold in volts and ICT is the
CT ramp current in µA, as described in the
Electrical
Characteristics
table.
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
______________________________________________________________________________________ 15
IN
R1
R2
VIN
FB_LDO
SGND
OUT_LDO
MAX15009
MAX15011
Figure 3. Setting the LDO Output Voltage
Table 1. EN_LDO/HHOOLLDDTruth/State Table
OPERATION STATE EN_LDO HOLD OUT_LDO COMMENT
Initial State Low Don’t care OFF
EN_LDO is pulled to SGND through an internal pulldown. HOLD
is unconnected and is internally pulled up to OUT_LDO. The
regulator is disabled.
Turn-On State High Don’t care ON EN_LDO is externally driven high turning regulator on. HOLD is
pulled up to OUT_LDO.
Hold Setup State High Low ON HOLD is externally pulled low while EN_LDO remains high
(latches EN_LDO state).
Hold State Low Low ON EN_LDO is driven low or left unconnected. HOLD remains
externally pulled low keeping the regulator on.
Off State Low High or
unconnected OFF
HOLD is driven high or left unconnected while EN_LDO is low.
The regulator is turned off and EN_LDO/HOLD logic returns to the
initial state.
MAX15009/MAX15011
Leave CT open to select a typical reset timeout of 19µs.
To maintain reset accuracy, use a low-leakage type of
capacitor.
Setting the Switch Current Limit
The switch block features accurate current-limit sens-
ing circuitry. A resistor connected from ILIM to SGND
can be used to select the current-limit threshold using
the following relationship:
ISW_LIM (mA) = RILIM (kΩ) x 1mA / kΩ
where 20kΩ≤RILIM ≤200kΩ.
Connect ILIM to OUT_LDO to select the default current
limit of 200mA (typ).
Programming the Switch
Overcurrent Blanking Time
The switch provides an adjustable overcurrent blanking
time to allow the safe charge of large capacitive loads.
When an overcurrent event is detected, a delay period
elapses before the condition is latched and the internal
MOSFET is turned off. This period is the overcurrent
delay, tOC_DELAY. Set the overcurrent delay using the
following equation:
tOC_DELAY = COC_DELAY x VOC_DELAY / IOC_DELAY_UP
where tOC_DELAY is in seconds and COC_DELAY is in
µF. VOC_DELAY is the overcurrent delay timeout thresh-
old voltage in volts and IOC_DELAY_UP is the overcur-
rent delay timeout pullup current in µA as seen in the
Electrical Characteristics
table.
Ensure that the switch is not disabled due to a large
startup inrush current by selecting a large enough
value for overcurrent blanking time. Assume that the
current available for charging the total switch output
capacitance, COUT_SW, is the difference between the
current-limit threshold value, ISW_LIM, and the nominal
DC load current at OUT_SW, IOUT_SW_NOM and select
the COC_DELAY using the following relationship:
COC_DELAY also affects the length of time before the
MAX15009/MAX15011 attempt to turn the switch back
on. Set the autoretry delay using the following equation:
tOC_RETRY = COC_DELAY x
VOC_DELAY/IOC_DELAY_DOWN
where tOC_RETRY is in seconds, COC_DELAY is in µF,
VOC_DELAY is in volts, and IOC_DELAY_DOWN is in µA.
COC_DELAY should be a low-leakage type of capacitor
with a minimum value of 100pF.
Setting the Overvoltage Threshold
(MAX15009 Only)
The MAX15009 provides an accurate means to set the
overvoltage threshold for the OVP controller using
FB_PROT. Use a resistive voltage-divider to set the
desired overvoltage threshold (Figure 4). FB_PROT has
a rising 1.235V threshold with a 4% falling hysteresis.
Begin by selecting the total end-to-end resistance,
RTOTAL = R3+ R4. Choose RTOTAL to yield a total current
equivalent to a minimum of 100 x IFB_PROT (FB_PROT’s
input maximum bias current) at the desired overvoltage
threshold. See the
Electrical Characteristics
table.
For example:
With an overvoltage threshold (VOV) set to 20V, RTOTAL
< 20V / (100 x IFB_PROT), where IFB_PROT is FB_PROT’s
maximum 100nA bias current:
RTOTAL < 2MΩ
CIVC
V(II )
OC_DELAY OC_DELAY_UP OUT_LDO OUT_SW
OC_DELAY SW_LIM OUT_SW_NOM
≥××
×−
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
16 ______________________________________________________________________________________
R4
R3
R5
R6
IN
VIN
FB_PROT
SGND
GATE
SOURCE
PROTECTOR
OUTPUT
MAX15009
IN
VIN
FB_PROT
SGND
GATE
SOURCE
PROTECTOR
OUTPUT
MAX15009
Figure 4. Setting the Overvoltage Threshold (MAX15009)
Use the following formula to calculate R4:
R4= VTH_PROT x RTOTAL / VOV
where VTH_PROT is the 1.235V FB_PROT rising threshold
and VOV is the desired overvoltage threshold. R4= 124kΩ:
RTOTAL = R3+ R4
where R3= 1.88MΩ. Use a standard 1.87MΩresistor.
A lower value for total resistance dissipates more
power, but provides better accuracy and robustness
against external disturbances.
Input Transients Clamping
When the external MOSFET is turned off during an
overvoltage event, stray inductance in the power path
may cause additional input-voltage spikes that exceed
the VDSS rating of the external MOSFET or the absolute
maximum rating for the MAX15009. Minimize stray
inductance in the power path using wide traces and
minimize the loop area included by the power traces
and the return ground path.
For further protection, add a zener diode or transient
voltage suppressor (TVS) rated below the absolute
maximum rating limits (Figure 5).
External MOSFET Selection
Select the external MOSFET with adequate voltage rating,
VDSS, to withstand the maximum expected load-dump
input voltage. The on-resistance of the MOSFET,
RDS(ON), should be low enough to maintain a minimal
voltage drop at full load, limiting the power dissipation
of the MOSFET.
During regular operation, the power dissipated by the
MOSFET is:
PNORMAL = ILOAD2x RDS(ON)
Normally, this power loss is small and is safely handled
by the MOSFET. However, when operating the
MAX15009 in overvoltage limiter mode under pro-
longed or frequent overvoltage events, select an exter-
nal MOSFET with an appropriate power rating.
During an overvoltage event, the power dissipation in
the external MOSFET is proportional to both load cur-
rent and to the drain-source voltage, resulting in high
power dissipated in the MOSFET (Figure 6). The power
dissipated across the MOSFET is:
POV_LIMITER = VQ1 x ILOAD
where VQ1 is the voltage across the MOSFET’s drain
and source during overvoltage limiter operation, and
ILOAD is the load current.
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
______________________________________________________________________________________ 17
IN
VIN
SGND
GATE
SOURCE
TVS
MAX15009 LOAD
Figure 5. Protecting the MAX15009 Input from High-Voltage
Transients
IN
FB_PROT
SGND
GATE
SOURCE
TVS
MAX15009
LOAD
ILOAD
+ VQ1 -
VSOURCE
VSOURCE
VOV
VMAX
Figure 6. Power Dissipated Across MOSFETs During an
Overvoltage Fault (Overvoltage Limiter Mode)
MAX15009/MAX15011
Overvoltage-Limiter Mode
Switching Frequency
When the MAX15009 is configured in overvoltage-
limiter mode, the external n-channel MOSFET is subse-
quently switched on and off during an overvoltage
event. The output voltage at OUT_PROT resembles a
periodic sawtooth waveform. Calculate the period of
the waveform, tOVP, by summing three time intervals
(Figure 7):
tOVP = t1+ t2+ t3
where t1is the VSOURCE output discharge time, t2 is the
GATE delay time, and t3is the VSOURCE output charge
time.
During an overvoltage event, the power dissipated
inside the MAX15009 is due to the gate pulldown cur-
rent, IGATEPD. This amount of power dissipation is
worse when ISOURCE = 0 (CSOURCE is discharged only
by the internal current sink).
The worst-case internal power dissipation contribution
in overvoltage limiter mode, POVP, in watts can be
approximated using the following equation:
where VOV is the overvoltage threshold voltage in volts
and IGATEPD is 100mA (max) GATE pulldown current.
Output Discharge Time (t
1
)
When the voltage at SOURCE exceeds the adjusted
overvoltage threshold, GATE’s internal pulldown is
enabled until VSOURCE drops by 4%. The internal cur-
rent sink, IGATEPD, and the external load current,
ILOAD, discharge the external capacitance from
SOURCE to ground.
Calculate the discharge time, t1, using the following
equation:
where t1is in ms, VOV is the adjusted overvoltage
threshold in volts, ILOAD is the external load current in
mA, and IGATEPD is the 100mA (max) internal pulldown
current of GATE. CSOURCE is the value of the capacitor
connected between the source of the MOSFET and
PGND in µF.
GATE Delay Time (t
2
)
When SOURCE falls 4% below the overvoltage-threshold
voltage, the internal current sink is disabled and the
internal charge pump begins recharging the external
GATE voltage. Due to the external load, the SOURCE
voltage continues to drop until the gate of the MOSFET is
recharged. The time needed to recharge GATE and re-
enhance the external MOSFET is approximately:
where t2is in µs, Ciss is the input capacitance of the
MOSFET in pF, and VGS(TH) is the GATE-to-SOURCE
threshold voltage of the MOSFET in volts. VFis the 0.7V
(typ) internal clamp diode forward voltage of the MOS-
FET in volts, and IGATE is the charge-pump current
45µA (typ). Any external capacitance between GATE
and PGND adds up to Ciss.
During t2, the SOURCE capacitance, CSOURCE, loses
charge through the output load. The voltage across
CSOURCE, ΔV2, decreases until the MOSFET reaches
its VGS(TH) threshold. Approximate ΔV2using the fol-
lowing formula:
SOURCE Output Charge Time (t
3
)
Once the GATE voltage exceeds the GATE-to-SOURCE
threshold, VGS(TH), of the external MOSFET, the MOS-
FET turns on and the charge through the internal
charge pump with respect to the drain potential, QG,
determines the slope of the output voltage rise. The
time required for the SOURCE voltage to rise again to
the overvoltage threshold is:
tCV
I
rss SOURCE
GATE
3=×Δ
ΔVIt
C
LOAD
SOURCE
22
=×
tC VV
I
iss
GS TH F
GATE
2=× +
()
tC 0.04 V
II
1 SOURCE OV
LOAD GATEPD
=×
×
+
PV I t
t
OVP OV GATEPD OVP
=×× ×098 1
.
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
18 ______________________________________________________________________________________
t2
t1
tOVP
t3
GATE
SOURCE
Figure 7. MAX15009 Timing Diagram
where VSOURCE = (VOV x 0.04) + V2 in volts, and Crss
is the MOSFET’s reverse transfer capacitance in pF.
Any external capacitance between GATE and PGND
adds up to Crss.
Power Dissipation/Junction Temperature
During normal operation, the MAX15009/MAX15011
have two main sources of internal power dissipation:
the LDO and the switched output.
The internal power dissipation due to the LDO can be
calculated as:
where VIN is the LDO input supply voltage in volts,
VOUT_LDO is the output voltage of the LDO in volts,
IOUT_LDO is the LDO total load current in mA, and
IOUT_SW is the switch load current in mA.
Calculate the power dissipation due to the switch as:
where ΔVSW is the switch dropout voltage in volts for
the given IOUT_SW current in mA.
The total power dissipation PDISS in mW as:
PDISS = PLDO + PSW
For prolonged exposure to overvoltage events, use the
VIN voltage expected during overvoltage conditions.
Under these circumstances the corresponding internal
power dissipation contribution, POVP, calculated in the
previous section should also be included in the total
power dissipation, PDISS.
For a given ambient temperature, TA, calculate the
junction temperature, TJ, as follows:
TJ= TA+ PDISS x θJA
where TJand TAare in °C and θJA is the junction-to-
ambient thermal resistance in °C/W as listed in the
Absolute Maximum Ratings
section.
The junction temperature should never exceed +150°C
during normal operation.
Thermal Protection
When the junction temperature exceeds TJ= +160°C,
the MAX15009/MAX15011 shut down to allow the
device to cool. When the junction temperature drops to
+140°C, the thermal sensor turns all enabled blocks on
again, resulting in a cycled output during continuous
thermal-overload conditions. Thermal protection pro-
tects the MAX15009/MAX15011 from excessive power
dissipation. For continuous operation, do not exceed
the absolute maximum junction temperature rating of
+150°C.
PVI
SW SW
=×ΔOUT SW_
P(VV )(I I )
IN OUT_LDO OUT_LDO OUT_SWLDO =− × +
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
______________________________________________________________________________________ 19
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
20 ______________________________________________________________________________________
Typical Operating Circuits
CRESET COC_DELAY
MAX15009
IN PGND
OUT_SW
FB_LDO
OUT_LDO
RESET
CT OC_DELAY
COC_DELAY
OC_DELAY
GATE
CIN
5V TO 40V INPUT
EN_LDOLDO ON/OFF
EN_SW
EN_PROT
SWITCH ON/OFF
ILIM
PROTECTOR ON/OFF
RILIM
RILIM
HOLDHOLD
COUT_SW
RPU
COUT_LDO
SOURCE FB_PROT
DC-DC
MAX5073
CSOURCE
VOUT2
SWITCH OUTPUT
5V
300mA
VOUT1
VCC
RESET/EN
I/O
μC
SGND
CRESET
ILIM
MAX15011
IN
OUT_SW
FB_LDO
OUT_LDO
RESET
CT PGND SGND
CIN
5V TO 40V INPUT
EN_LDOLDO ON/OFF
EN_SWSWITCH ON/OFF
COUT_SW
RPU
COUT_LDO
HOLDHOLD
SWITCH OUTPUT
5V
300mA VCC
RESET/EN
I/O
μC
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
______________________________________________________________________________________ 21
Chip Information
PROCESS: BiCMOS
MAX15011
TQFN
(5mm x 5mm)
+
TOP VIEW
29
30
28
27
12
11
13
N.C.
N.C.
SGND
PGND
RESET
14
N.C.
OC_DELAY
OUT_LDO
IN
ILIM
IN
N.C.
12
OUT_SW
4567
2324 22 20 19 18
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C. OUT_LDO
3
21
31 10
N.C. N.C.
32 9
N.C. CT
OUT_SW
26 15 FB_LDO
*EP
*EP = EXPOSED PAD
N.C.
25 16 EN_LDO
N.C. EN_SW
8
17
HOLD
Pin Configurations (continued)
PART LDO SWITCHED
OUTPUT
OVP
CONTROLLER
MAX15009 √√ √
MAX15011 √√ —
Selector Guide
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
22 ______________________________________________________________________________________
QFN THIN.EPS
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
______________________________________________________________________________________ 23
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
24
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 8/07 Initial release —
1 1/08 Removed future product asterisks, updated Electrical Characteristics table and
Typical Operating Characteristics section. 1, 2, 6, 8