General Description
The MAX1792 low-dropout linear regulator operates
from a +2.5V to +5.5V supply and delivers a guaran-
teed 500mA load current with low 130mV dropout. The
high-accuracy (±1%) output voltage is preset at an
internally trimmed voltage (see
Selector Guide
) or can
be adjusted from 1.25V to 5.0V with an external resis-
tive divider.
An internal PMOS pass transistor allows the low 80µA
supply current to remain independent of load, making
this device ideal for portable battery-operated equip-
ment such as personal digital assistants (PDAs), cellu-
lar phones, cordless phones, base stations, and
notebook computers.
Other features include an active-low open-drain reset
output with a 4ms timeout period that indicates when
the output is out of regulation, a 0.1µA shutdown mode,
short-circuit protection, and thermal shutdown protec-
tion. The device is available in a miniature 1.3W, 8-pin
power-µMAX package with a metal pad on the under-
side of the package.
________________________Applications
Notebook Computers
Cellular and Cordless Telephones
Personal Digital Assistants (PDAs)
Palmtop Computers
Base Stations
USB Hubs
Docking Stations
Features
♦Guaranteed 500mA Output Current
♦Low 130mV Dropout at 500mA
♦Up to ±1% Output Voltage Accuracy
Preset at 1.5V, 1.8V, 2.5V, 3.3V, or 5.0V
Adjustable from 1.25V to 5.0V
♦Reset Output with 4ms Timeout Period
♦Low 80µA Ground Current
♦0.1µA Shutdown Current
♦Thermal Overload Protection
♦Output Current Limit
♦Tiny 1.3W Power-µMAX Package
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
________________________________________________________________
Maxim Integrated Products
1
POWER-μMAX
SET
GND
+
EP
SHDN
1
2
8
7
OUT
OUTIN
RST
IN
TOP VIEW
3
4
6
5
MAX1792
Pin Configuration
NC
MAX1792
IN
IN
CIN
1μF
COUT
3.3μF
RRST
100k
VIN = +2.5V TO +5.5V
ON
OFF
SHDN
OUT VOUT
OUT
RST
GNDSET
TO
μC
Typical Operating Circuit
19-1699; Rev 2; 11/11
Ordering Information
Selector Guide
PART AND SUFFIX VOUT μMAX TOP MARK
MAX1792EUA15+ 1.5V or Adj. AAAE
MAX1792EUA18+ 1.8V or Adj. AAAA
MAX1792EUA25+ 2.5V or Adj. AAAB
MAX1792EUA33+ 3.3V or Adj. AAAC
MAX1792EUA50+ 5.0V or Adj. AAAD
MAX1792EUA33/V+ 3.3V or Adj. AACP
PART* TEMP RANGE PIN-PACKAGE
MAX1792EUA_ _+ -40°C to +85°C 8 Power-μMAX
MAX1792EUA_ _/V+ -40°C to +85°C 8 Power-μMAX
*
Insert the desired two-digit suffix (see Selector Guide) into the
blanks to complete the part number.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
Contact factory for other preset output voltages.
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.
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = VOUT(NOM) + 500mV, or VIN = +2.5V (whichever is greater), SHDN = IN, TA= 0°C to +85°C, unless otherwise noted. Typical
values are at TA= +25°C.)
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.
IN, SHDN, RST, SET to GND ....................................-0.3V to +6V
OUT to GND ................................................-0.3V to (VIN + 0.3V)
Output Short-Circuit Duration ........................................Indefinite
Continuous Power Dissipation (TA= +70°C)
8-Pin Power-µMAX (derate 17mW/°C above +70°C).......1.3W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
Dual Mode is a trademark of Maxim Integrated Products.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage VIN 2.5 5.5 V
Input Undervoltage Lockout VUVLO Rising, 75mV hysteresis 2.0 2.15 2.3 V
Preset VOUT 2.5V -1 +1
IOUT = 100mA,
TA = +85°CPreset VOUT < 2.5V -1.5 +1.5 %
IOUT = 100mA, TA = 0°C to +85°C -2 +2
Output Voltage Accuracy
(Preset Mode) VOUT
IOUT = 1mA to 500mA, VIN > VOUT + 0.5V,
TA = 0°C to +85°C-3 +3
%
Adjustable Output Voltage
Range 1.25 5 V
TA = +85°C 1.229 1.250 1.271
SET Voltage Threshold
(Adjustable Mode) VSET
VIN = +2.7V,
VOUT set to 2.0V,
IOUT = 100mA TA = 0°C to +85°C 1.219 1.281
V
Maximum Output Current IOUT V
IN 2.7V 500 mARMS
Short-Circuit Current Limit ILIM V
OUT = 0V, VIN 2.7V 0.55 0.8 1.8 A
In-Regulation Current Limit VOUT > 96% of nominal value, VIN 2.7V 1.6 A
SET Dual Mode™ Threshold 50 100 150 mV
SET Input Bias Current ISET V
SET = 1.25V -100 +100 nA
IOUT = 1mA 80 250
Ground-Pin Current IQIOUT = 500mA 110 μA
VOUT = 5.0V 120 225
VOUT = 3.3V 130 250
Dropout Voltage (Note 1) VIN -
VOUT IOUT = 500mA
VOUT = 2.5V 210 360
mV
Line Regulation VLNR VIN from (VOUT + 100mV) to 5.5V,
ILOAD = 5mA -0.15 0 +0.15 %/V
Load Regulation VLDR I
OUT = 1mA to 500mA 0.4 1.0 %
Output Voltage Noise 10Hz to 1MHz, COUT = 3.3μF (ESR < 0.1) 115 μVRMS
SHUTDOWN
Shutdown Supply Current IOFF SHDN = GND, VIN = 5.5V 0.1 15 μA
VIH 2.5V < VIN < 5.5V 1.6
SHDN Input Threshold VIL 2.5V < VIN < 5.5V 0.6 V
SHDN Input Bias Current SHDN = IN or GND 10 100 nA
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS
(VIN = VOUT(NOM) + 500mV, or VIN = +2.5V (whichever is greater), SHDN = IN, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT(NOM) + 500mV, or VIN = +2.5V (whichever is greater), SHDN = IN, TA= 0°C to +85°C, unless otherwise noted. Typical
values are at TA= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RESET OUTPUT
Reset Output Low Voltage VOL RST sinking 1mA 0.01 0.1 V
Operating Voltage Range for
Valid Reset RST sinking 100μA 1.0 5.5 V
RST Output High Leakage
Current V
RST = +5.5V 100 nA
RST Threshold Rising edge, referred to VOUT(NOMINAL) 90 93 96 %
RST Release Delay tRP Rising edge of OUT to rising edge of RST 1.5 4.5 8 ms
THERMAL PROTECTION
Thermal Shutdown Temperature TSHDN 170 °C
Thermal Shutdown Hysteresis TSHDN 20 °C
PARAMETER SYMBOL CONDITIONS MIN MAX UNITS
Input Voltage VIN 2.5 5.5 V
Input Undervoltage Lockout VUVLO Rising or falling 2.0 2.3 V
IOUT = 100mA -2 +2
Output Voltage Accuracy
(Preset Mode) VOUT IOUT = 1mA to 500mA -3 +3 %
Adjustable Output Voltage
Range 1.25 5 V
SET Voltage Threshold
(Adjustable Mode) VSET I
OUT = 100mA 1.212 1.288 V
Maximum Output Current IOUT 500 mARMS
Short-Circuit Current Limit ILIM V
OUT = 0V 0.55 1.8 A
SET Dual Mode Threshold 50 150 mV
SET Input Bias Current ISET V
SET = 1.25V -100 +100 nA
Ground-Pin Current IQ I
OUT = 1mA 250 μA
VOUT = 5.0V 225
VOUT = 3.3V 250
Dropout Voltage (Note 1) VIN -
VOUT IOUT = 500mA
VOUT = 2.5V 360 mV
Line Regulation VLNR VIN from (VOUT + 100mV) to 5.5V,
ILOAD = 5mA -0.15 +0.15 %/V
Load Regulation VLDR I
OUT = 1mA to 500mA 1.0 %
SHUTDOWN
Shutdown Supply Current IOFF SHDN = GND, VIN = +5.5V 15 μA
VIH 2.5V < VIN < 5.5V 1.6
SHDN Input
Threshold VIL 2.5V < VIN < 5.5V 0.6 V
SHDN Input Bias Current ISHDN SHDN = IN or GND 100 nA
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
2.0 3.0 3.52.5 4.0 4.5 5.0 5.5
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
MAX1792-01
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
IOUT = 0A
IOUT = 500mA
3.27
3.28
3.29
3.30
3.31
3.32
3.33
0 200100 300 400 500 600 700 800
OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX1792-02
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
3.27
3.29
3.28
3.31
3.30
3.32
3.33
-40 10-15 35 60 85
OUTPUT VOLTAGE
vs. TEMPERATURE
MAX1792-03
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
VIN = VOUT + 500mV
IOUT = 0A
0
50
150
100
200
250
0 200 300100 400 500 600 700 800
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX1792-04
LOAD CURRENT (mA)
DROPOUT VOLTAGE (mV)
TA = +85°C
TA = -40°C
TA = +25°C
0
40
20
80
60
120
100
140
0 1.0 1.5 2.00.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5
GROUND-PIN CURRENT
vs. INPUT VOLTAGE
MAX1792-05
INPUT VOLTAGE (V)
GROUND-PIN CURRENT (μA)
IOUT = 500mA
IOUT = 0A
60
80
70
100
90
110
120
130
140
0 200 300100 400 500 600 700 800
GROUND-PIN CURRENT
vs. LOAD CURRENT
MAX1792-06
LOAD CURRENT (mA)
GROUND-PIN CURRENT (μA)
VIN = 5.5V
VIN = 3.8V
Typical Operating Characteristics
(MAX1792EUA33, VIN = VOUT + 500mV, SHDN = IN, CIN = 1µF, COUT = 3.3µF, TA= +25°C, unless otherwise noted.)
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT(NOM) + 500mV, or VIN = +2.5V (whichever is greater), SHDN = IN, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
Note 1: Dropout voltage is defined as VIN - VOUT, when VOUT is 100mV below the value of VOUT measured when VIN = VOUT(NOM)
+ 0.5V. Since the minimum input voltage is 2.5V, this specification is only meaningful when VOUT(NOM) ≥2.5V. For VOUT(NOM)
between 2.5V and 3.5V, use the following equations: Typical Dropout = -93mV/V ✕VOUT(NOM) + 445mV; Guaranteed Maximum
Dropout = -137mV/V ✕VOUT(NOM) + 704mV. For VOUT(NOM) ≥3.5V: Typical Dropout = 120mV; Guaranteed Maximum Dropout
= 225mV.
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
PARAMETER SYMBOL CONDITIONS MIN MAX UNITS
RESET OUTPUT
Reset Output Low Voltage VOL RST sinking 1mA 0.1 V
Operating Voltage Range for
Valid Reset RST sinking 100μA 1.0 5.5 V
RST Output High Leakage
Current V
RST = +5.5V 100 nA
RST Threshold Rising edge, referred to VOUT(NOMINAL) 90 96 %
RST Release Delay tRP Rising edge of OUT to rising edge of RST 1.5 8 ms
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
_______________________________________________________________________________________
5
OUTPUT NOISE DC TO 1MHz
MAX1792-10
20ms/div
VOUT
200μV/div
VOUT = 3.3V
ROUT = 66Ω (50mA)
100
0.01
0 200100 400 600
REGION OF STABLE COUT ESR
vs. LOAD CURRENT
0.1
1
10
MAX1792-11
LOAD CURRENT (mA)
COUT ESR (Ω)
300 500 700 800
STABLE REGION
COUT = 3.3μF
COUT = 10μF
LOAD-TRANSIENT RESPONSE
MAX1792-12
10μs/div
IOUT
500mA/div
VOUT
20mV/div
VIN = VOUT + 500mV
CIN = 10μF
ROUT = 660Ω TO 6.6Ω (5mA TO 500mA)
60
70
65
80
75
90
85
95
-40 10-15 35 60 85
GROUND-PIN CURRENT
vs. TEMPERATURE
MAX1792-07
TEMPERATURE (°C)
GROUND-PIN CURRENT (μA)
VIN = VOUT + 500 mV
IOUT = 0A
-80
0
0.01 0.1 1000
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-10
-30
-60
-70
MAX1792-08
FREQUENCY (kHz)
PSRR (dB)
110
-50
-40
-20
100
COUT = 3.3μF
IOUT = 50mA
0.1 1 10 100 1000
OUTPUT SPECTRAL NOISE DENSITY
vs. FREQUENCY
MAX1792-09
FREQUENCY (kHz)
OUTPUT SPECTRAL NOISE DENSITY (μV/√Hz)
10
0.001
0.01
0.1
1
COUT = 3.3μF
IOUT = 50mA
Typical Operating Characteristics (continued)
(MAX1792EUA33, VIN = VOUT + 500mV, SHDN = IN, CIN = 1µF, COUT = 3.3µF, TA= +25°C, unless otherwise noted.)
500mA Low-Dropout
Linear Regulator in µMAX
6 _______________________________________________________________________________________
SHUTDOWN WAVEFORM
MAX1792-15
20μs/div
VSHDN
1V/div
VOUT
1V/div
0V
0V
2V
3V
ROUT = 6.6Ω (500mA)
RST WAVEFORM
MAX1792-16
20ms/div
VIN
2.5V/div
VOUT
2V/div
0V
5V
0V
0V
ROUT = 66Ω (50mA)
VRST
2V/div
MAX1792
Pin Description
LINE-TRANSIENT RESPONSE
MAX1792-14
100μs/div
VIN
1V/div
VOUT
10mV/div
6V
3V
Typical Operating Characteristics (continued)
(MAX1792EUA33, VIN = VOUT + 500mV, SHDN = IN, CIN = 1µF, COUT = 3.3µF, TA= +25°C, unless otherwise noted.)
PIN NAME FUNCTION
1, 2 IN Regulator Input. Supply voltage can range from +2.5V to +5.5V. Bypass with a 1µF capacitor to GND (see
Capacitor Selection and Regulator Stability). Connect both input pins together externally.
3RST
Open-Drain Active-Low Reset Output. RST remains low while the output voltage (VOUT) is below the reset
threshold and for at least 4ms after VOUT rises above the reset threshold. Connect a 100kΩ pullup resistor
to OUT to obtain an output voltage.
4SHDN Active-Low Shutdown Input. A logic low reduces supply current to 0.1µA. In shutdown, the RST output is
low and OUT is pulled low through an internal 5kΩ resistor. Connect to IN for normal operation.
5 GND Ground. This pin and the exposed pad also function as a heatsink. Solder both to a large pad or to the
circuit-board ground plane to maximize power dissipation.
6 SET Voltage-Setting Input. Connect to GND for preset output. Connect to a resistive divider between OUT and
GND to set the output voltage between 1.25V and 5.0V.
7, 8 OUT Regulator Output. Sources up to 500mA. Bypass with a 3.3µF low-ESR capacitor to GND. Use a 4.7µF
capacitor for output voltages below 2V. Connect both output pins together externally.
—EP
Exposed Pad. Solder to ground plane to maximize thermal performance. Not internally connected to
ground.
Detailed Description
The MAX1792 is a low-dropout, low-quiescent-current
linear regulator designed primarily for battery-powered
applications. The device supplies loads up to 500mA
and is available with preset output voltages. As illustrat-
ed in Figure 1, the MAX1792 consists of a 1.25V refer-
ence, error amplifier, P-channel pass transistor, and
internal feedback voltage-divider.
The 1.25V reference is connected to the error amplifier,
which compares this reference with the feedback volt-
age and amplifies the difference. If the feedback volt-
age is lower than the reference voltage, the
pass-transistor gate is pulled lower, which allows more
current to pass to the output and increases the output
voltage. If the feedback voltage is too high, the pass-
transistor gate is pulled up, allowing less current to
pass to the output.
The output voltage is fed back through either an inter-
nal resistive divider connected to OUT or an external
resistor network connected to SET. The Dual Mode
comparator examines VSET and selects the feedback
path. If VSET is below 50mV, the internal feedback path
is used and the output is regulated to the factory-preset
voltage.
Additional blocks include an output current limiter, ther-
mal sensor, and shutdown logic.
Internal P-Channel Pass Transistor
The MAX1792 features a 0.25ΩP-channel MOSFET
pass transistor. Unlike similar designs using PNP pass
transistors, P-channel MOSFETs require no base drive,
which reduces quiescent current. PNP-based regula-
tors also waste considerable current in dropout when
the pass transistor saturates, and use high base-drive
currents under large loads.
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
_______________________________________________________________________________________ 7
100mV
SHDN
IN
IN
RST
ON
OFF
CIN
1μF
VIN = +2.5V TO +5.5V
OUT
OUT
VOUT = 1.25V TO 5.0V
COUT
3.3μF
THERMAL
SENSOR
SET
MOSFET
DRIVER WITH
ILIM
DELAY
TIMER
SHUTDOWN
LOGIC VREF
1.25V
ERROR
AMPLIFIER
GND
R1
R2
RRST
100k
LOGIC SUPPLY
VOLTAGE (VOUT)
93% VREF
TO
μC
5k
MAX1792
Figure 1. Functional Diagram
MAX1792
The MAX1792 does not suffer from these problems and
consumes only 110µA of quiescent current under
heavy loads as well as in dropout.
Output Voltage Selection
The MAX1792’s Dual Mode operation allows operation
in either a preset voltage mode or an adjustable mode.
Connect SET to GND to select the preset output volt-
age. The two-digit part number suffix identifies the out-
put voltage (see
Selector Guide
). For example, the
MAX1792EUA33 has a preset 3.3V output voltage.
The output voltage may also be adjusted by connecting
a voltage-divider from OUT to SET to GND (Figure 2).
Select R2 in the 25kΩto 100kΩrange. Calculate R1
with the following equation:
R1 = R2 [(VOUT / VSET) - 1]
where VSET = 1.25V and VOUT may range from 1.25V to
5.0V.
Shutdown
Pull SHDN low to enter shutdown. During shutdown, the
output is disconnected from the input and supply current
drops to 0.1µA. When in shutdown, RST pulls low and
OUT is discharged through an internal 5kΩresistor. The
capacitance and load at OUT determine the rate at
which VOUT decays. SHDN can be pulled as high as
+6V, regardless of the input and output voltage.
Reset Output
The reset output (RST) pulls low when OUT is less than
93% of the nominal regulation voltage. Once OUT
exceeds 93% of the nominal voltage, RST goes high
impedance after 4ms. RST is an open-drain N-channel
output. To obtain a voltage output, connect a pullup
resistor from RST to OUT. A 100kΩresistor works well for
most applications. RST can be used as a power-on-reset
(POR) signal to a microcontroller (µC), or drive an exter-
nal LED to indicate power failure. When the MAX1792 is
shut down, RST is held low independent of the output
voltage. If unused, leave RST grounded or unconnected.
Current Limit
The MAX1792 monitors and controls the pass transis-
tor’s gate voltage, limiting the output current to 0.8A
(typ). This current limit doubles when the output voltage
is within 4% of the nominal value to improve perfor-
mance with large load transients. The output can be
shorted to ground for an indefinite period of time with-
out damaging the part.
Thermal Overload Protection
Thermal overload protection limits total power dissipa-
tion in the MAX1792. When the junction temperature
exceeds TJ= +170°C, a thermal sensor turns off the
pass transistor, allowing the device to cool. The thermal
sensor turns the pass transistor on again after the junc-
tion temperature cools by 20°C, resulting in a pulsed
output during continuous thermal overload conditions.
Thermal overload protection protects the MAX1792 in
the event of fault conditions. For continuous operation,
do not exceed the absolute maximum junction-temper-
ature rating of TJ= +150°C.
Operating Region and
Power Dissipation
The MAX1792’s maximum power dissipation depends on
the thermal resistance of the IC package and circuit
board, the temperature difference between the die junc-
tion and ambient air, and the rate of air flow. The power
dissipated in the device is P = IOUT x (VIN - VOUT). The
maximum allowed power dissipation is 1.3W or:
PMAX = (TJ(MAX) - TA) / ( θJC + θCA)
where TJ- TAis the temperature difference between
the MAX1792 die junction and the surrounding air, θJC
is the thermal resistance from the junction to the case,
and θCA is the thermal resistance from the case
through the PC board, copper traces, and other materi-
als to the surrounding air.
The MAX1792 package features an exposed thermal
pad on its underside. This pad lowers the thermal resis-
tance of the package by providing a direct heat con-
500mA Low-Dropout
Linear Regulator in µMAX
8 _______________________________________________________________________________________
OUT
OUT
SET
GND
IN
IN
SHDN
RST
COUT
3.3μF
VOUT
VOUT
CIN
1μF
ON
OFF
VIN = +2.5V TO +5.5V
R2
R1 = R2 - 1
1.25V
MAX1792 R1
Figure 2. Adjustable Output Using External Feedback
Resistors
duction path from the die to the PC board. Additionally,
the MAX1792’s ground pin (GND) performs the dual
function of providing an electrical connection to system
ground and channeling heat away. Connect the
exposed backside pad and GND to the system ground
using a large pad or ground plane, or multiple vias to
the ground plane layer.
The MAX1792 delivers up to 0.5A(RMS) and operates
with input voltages up to 5.5V, but not simultaneously.
High output currents can only be sustained when input-
output differential voltages are low, as shown in Figure 3.
Applications Information
Capacitor Selection
and Regulator Stability
Capacitors are required at the MAX1792’s input and
output for stable operation over the full temperature
range and with load currents up to 500mA. Connect a
1µF capacitor between IN and ground and a 3.3µF low
equivalent series resistance (ESR) capacitor between
OUT and ground. For output voltages less than 2V, use
a 4.7µF low-ESR output capacitor. The input capacitor
(CIN) lowers the source impedance of the input supply.
Reduce noise and improve load-transient response,
stability, and power-supply rejection by using larger
output capacitors such as 10µF.
The output capacitor’s (COUT) ESR affects stability and
output noise. Use output capacitors with an ESR of
0.1Ωor less to ensure stability and optimum transient
response. Surface-mount ceramic capacitors have very
low ESR and are commonly available in values up to
10µF. Connect CIN and COUT as close to the MAX1792
as possible to minimize the impact of PC board trace
inductance.
Noise, PSRR, and Transient Response
The MAX1792 is designed to operate with low dropout
voltages and low quiescent currents in battery-powered
systems while still maintaining good noise, transient
response, and AC rejection. See the
Typical Operating
Characteristics
for a plot of Power-Supply Rejection
Ratio (PSRR) vs. Frequency. When operating from
noisy sources, improved supply-noise rejection and
transient response can be achieved by increasing the
values of the input and output bypass capacitors and
through passive filtering techniques.
The MAX1792 load-transient response graphs (see
Typical Operating Characteristics
) show two compo-
nents of the output response: a DC shift from the output
impedance due to the load current change, and the
transient response. A typical transient response for a
step change in the load current from 5mA to 500mA is
18mV. Increasing the output capacitor’s value and
decreasing the ESR attenuates the overshoot.
Input-Output (Dropout) Voltage
A regulator’s minimum input-to-output voltage differen-
tial (dropout voltage) determines the lowest usable sup-
ply voltage. In battery-powered systems, this
determines the useful end-of-life battery voltage.
Because the MAX1792 uses a P-channel MOSFET pass
transistor, its dropout voltage is a function of drain-to-
source on-resistance (RDS(ON)) multiplied by the load
current (see
Typical Operating Characteristics
):
VDROPOUT = VIN - VOUT = RDS(ON) x IOUT
The MAX1792 ground current remains below 150µA in
dropout.
Note: The MAX1792 has an exposed thermal pad on
the bottom side of the package.
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
_______________________________________________________________________________________ 9
Figure 3. Power Operating Regions: Maximum Output Current
vs. Supply Voltage
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
MAXIMUM OUTPUT CURRENT (A)
4.0 4.5
00.5 3.53.02.5
2.01.5
1.0
INPUT-OUTPUT VOLTAGE DIFFERENTIAL (V)
MAXIMUM SUPPLY
VOLTAGE LIMIT
(VOUT = 1.25V)
POWER-μMAX PACKAGE OPERATING
REGION AT TJ(MAX) = +150°C
TA = +50°C
TA = +70°C
TA = +85°C
CONTINUOUS CURRENT LIMIT
TYPICAL VDROPOUT LIMIT
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maxim-ic.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
µMAX-EP U8E+2 21-0107 90-0145
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
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.
10
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
1 8/08 Updated Pin Description and Package Information 6, 10
2 11/11
Updated the Ordering Information and Selector Guide to include lead(Pb)-free and
automotive qualified parts; added the soldering information to the Absolute Maximum
Ratings section; added the Package Information table
1, 2, 9