General Description
The MAX8869 low-dropout linear regulator operates
from a +2.7V to +5.5V input and delivers a guaranteed
1A load current with a low 200mV dropout. The high-
accuracy (±1%) output voltage is preset at +5V, +3.3V,
+2.5V, +1.8V, or +1.0V or is adjustable from +0.8V to
+5V with an external resistor-divider.
The MAX8869 uses Microcap®technology and
requires only a small 1µF output capacitor for guaran-
teed stability. An internal PMOS pass transistor allows
low 500µA supply current, making this regulator useful
for networking and telecom hardware as well as bat-
tery-operated equipment. Other features include soft-
start, low-power shutdown, short-circuit protection, and
thermal shutdown protection.
The MAX8869 is available in a 1.5W, 16-pin TSSOP
package, which is 30% smaller than a SOT223 and only
1.1mm high.
________________________Applications
Telecom Hardware
Network Equipment
Mobile Phone Base Stations
Personal Computers
Notebook Computers
Features
oGuaranteed 1A Output Current
oStable with COUT = 1μF
oLow 200mV Dropout at 1A
o±1% Output Voltage Accuracy
Preset at +5V, +3.3V, +2.5V, +1.8V, or +1.0V
and Adjustable from +0.8V to +5.0V
o54dB PSRR at 100kHz
oAdjustable Soft-Start
o3ms Reset Output
oFoldback Output Current Limit
oThermal Overload Protection
oHigh-Power 16-Pin TSSOP Package (1.5W)
30% Smaller than SOT223 (Only 1.1mm High)
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
________________________________________________________________
Maxim Integrated Products
1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
N.C. N.C.
OUT
OUT
OUT
OUT
SET
GND
N.C.
TOP VIEW
MAX8869
TSSOP-EP
IN
IN
RST
IN
IN
SHDN
SS
Pin Configuration
IN
IN
IN
IN
SHDN
SS
OUT
OUT
OUT
OUT
RST
SET
GND
ON OFF
1μF1μF
VIN
+2.7V TO +5.5V
VOUT
UP TO 1A
RESET
OUTPUT
MAX8869
Typical Operating Circuit
19-1692; Rev 1; 3/11
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.
Ordering Information
Microcap is a registered trademark of American Technical
Ceramics Corp.
PART PIN-PACKAGE VOUT (V)*
MAX8869EUE50+ 16 TSSOP-EP** +5.0
MAX8869EUE33+ 16 TSSOP-EP** +3.3
MAX8869EUE25+ 16 TSSOP-EP** +2.5
MAX8869EUE18+ 16 TSSOP-EP** +1.8
MAX8869EUE10+ 16 TSSOP-EP** +1.0
Note: All devices are specified over the -40°C to +85°C
temperature range.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
*
Or adjustable from +0.8V to +5.0V. Contact factory for other
preset output voltages.
**
EP = Exposed pad.
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = +2.7V or VOUT(NOM) + 0.5V (whichever is greater), SHDN = IN, SS = open, SET = GND, COUT = 1µF, 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, SS to GND ......................................-0.3V to +6V
OUT, SET to GND ........................................-0.3V to (VIN + 0.3V)
Output Short-Circuit Duration ........................................Indefinite
Continuous Power Dissipation (TA= +70°C)
16-Pin TSSOP-EP (derate 26.1mW/°C above +70°C)......2.0W
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
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage Range VIN 2.7 5.5 V
Input Undervoltage Lockout Typical hysteresis = 50mV 2.35 2.45 2.55 V
Output Voltage Accuracy IOUT = 1mA, TA = +85°C-11%
SET Regulation Voltage
(Adjustable Mode) IOUT = 150mA, TA = +85°C 792 800 808 mV
Line Regulation ΔVLNR VIN = VOUT + 0.5V to +5.5V, IOUT = 10mA 0.1 %/V
Load Regulation ΔVLDR IOUT = 1mA to 1A 0.8 1.5 %/A
Ad j ustab l e O utp ut V ol tag e Range 0.8 5 V
Maximum Output Current IOUT Continuous 1 ARMS
Short-Circuit Current Limit ILIM VOUT = 0V 1.0 1.9 A
In-Regulation Current Limit ILIM VSET = 0.76V 2.0 4.0 A
SET Dual Mode Threshold 40 80 120 mV
SET Input Bias Current ISET VSET = +0.9V 50 300 nA
IOUT = 100µA 0.5 2.0
Ground Current IGND IOUT = 1A 2.5 mA
IOUT = 1mA, +2.7V < VIN < +5.5V 0.2
Dropout Voltage
(Note 1) IOUT = 1A, VOUT = +3.3V (Note 2) 200 350 mV
Output Voltage Noise f = 10Hz to 1M Hz, COU T = 1µF, IOU T = 150mA 150 µVRMS
Power-Supply Rejection Ratio PSRR f = 100kHz, COUT = 1µF 54 dB
Shutdown Supply Current IOFF SHDN = GND, VIN = +5.5V, VOUT = 0 0.1 10 µA
VIH 1.6
SHDN Input Threshold VIL
+2.7V < VIN
< +5.5V 0.6 V
SHDN Input Bias Current SHDN = GND or IN 0 0.1 µA
Soft-Start Charge Current ISS VSS = 0V 6 µA
RST Output Low Voltage ISINK = 1mA 0.1 V
IN Operating Voltage Range for
RST Valid ISINK = 10μA 1.0 5.5 V
RST Leakage V
RST = +5.5V 0.01 1 µA
RST Trip Level Referred to
Nominal VOUT Falling edge, typical hysteresis = 10mV 89 92 95 % OUT
RST Release Delay Rising edge 1 3 5.5 ms
Thermal Shutdown Threshold TSHDN Typical thermal hysteresis = +20°C +170
o
C
Dual Mode is a trademark of Maxim Integrated Products.
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS
(VIN = +2.7V or VOUT(NOM) + 0.5V (whichever is greater), SHDN = IN, SS = open, SET = GND, COUT = 1µF, TA= -40°C to +85°C,
unless otherwise noted.) (Note 3)
Note 1: Dropout voltage is (VIN - VOUT) when VOUT falls to 100mV below the value of VOUT measured when VIN = VOUT(NOM) +0.5V.
Since the minimum input voltage is 2.7V, this specification is only meaningful when VOUT ≥2.7V.
Note 2: The output voltage is externally set using a resistive voltage-divider from OUT to SET.
Note 3: Specifications to -40°C are guaranteed by design, not production tested.
PARAMETER SYMBOL CONDITIONS MIN MAX UNITS
Input Voltage Range VIN 2.7 5.5 V
Input Undervoltage Lockout Typical hysteresis = 50mV 2.3 2.6 V
Output Voltage Accuracy IOUT = 1mA, TA = +85°C -1 1 %
SET Regulation Voltage
(Adjustable Mode) IOUT = 150mA, TA = +85°C 792 808 mV
Load Regulation ΔVLDR IOUT = 1mA to 1A 2.0 %/A
Ad j ustab l e O utp ut V ol tag e Rang e 0.8 5 V
Maximum Output Current IOUT Continuous 1 ARMS
Short-Circuit Current Limit ILIM VOUT = 0V 1.0 A
In-Regulation Current Limit ILIM VSET = +0.76V 2.0 A
SET Dual Mode Threshold 40 120 mV
SET Input Bias Current ISET VSET = +0.9V 300 nA
Ground Current IGND IOUT = 100µA 2.0 mA
Dropout Voltage (Note 1) IOUT = 1A, VOUT = +3.3V (Note 2) 350 mV
Shutdown Supply Current IOFF SHDN = GND, VIN = +5.5V, VOUT = 0V 10 µA
VIH 1.7
SHDN Input Threshold VIL
+2.7V < VIN < +5.5V 0.6 V
SHDN Input Bias Current SHDN = GND or IN 0.1 µA
RST Output Low Voltage ISINK = 1mA 0.1 V
IN Operating Voltage Range for
RST Valid ISINK = 10µA 1.0 5.5 V
RST Leakage V
RST = +5.5V 1 µA
RST Trip Level Referred to
Nominal VOUT Falling edge, typical hysteresis = 10mV 88 95 % OUT
RST Release Delay Rising edge 1 6 ms
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VIN = +5V, VOUT = +2.5V, SHDN = IN, SS = open, COUT = 1µF, TA= +25°C, unless otherwise noted.)
0
-1.0
-0.5
-2.0
-1.5
-2.5
-3.0
0 1.0 1.50.5 2.0 2.5 3.0
OUTPUT VOLTAGE DEVIATION
vs. OUTPUT CURRENT
MAX8869-01
OUTPUT CURRENT (A)
OUTPUT VOLTAGE DEVIATION (%)
VIN = +5V
VIN = +3V
IOUT = 250mA
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
-40 -15 10 35 60 85
OUTPUT VOLTAGE DEVIATION
vs. TEMPERATURE
MAX8869-02
TEMPERATURE (°C)
OUTPUT VOLTAGE DEVIATION (%)
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
023145
GROUND CURRENT
vs. INPUT VOLTAGE
MAX8869-03
INPUT VOLTAGE (V)
GROUND CURRENT (mA)
IOUT = 0.5A
IOUT = 1A
IOUT = 0A
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
0 400200 600 800 1000
GROUND CURRENT
vs. OUTPUT CURRENT
MAX8869-04
OUTPUT CURRENT (mA)
GROUND CURRENT (mA)
VIN = +3V
VIN = +5V
0
0.5
1.5
1.0
2.0
2.5
-40 10-15 35 60 85
GROUND CURRENT
vs. TEMPERATURE
MAX8869-05
TEMPERATURE (°C)
GROUND CURRENT (mA)
IOUT = 250mA
IOUT = 0V
VIN = +3VVIN = +5V
0
100
50
250
200
150
400
350
300
450
0 500250 750 1000 1250 1500
DROPOUT VOLTAGE
vs. OUTPUT CURRENT
MAX8869-06
OUTPUT CURRENT (mA)
DROPOUT VOLTAGE (mV)
VOUT = +3.3V
0
100
50
200
150
250
300
2.5 3.53.0 4.0 4.5 5.0
DROPOUT VOLTAGE
vs. INPUT VOLTAGE
MAX8869-07
INPUT VOLTAGE (V)
DROPOUT VOLTAGE (mV)
IOUT = 500mA
IN DROPOUT, VOUT ≅ VIN
0
20
10
40
30
60
50
0.01 10.1 10 100 1000
PSRR vs. FREQUENCY
MAX8869-08
FREQUENCY (kHz)
PSRR (dB)
IOUT = 300mA
10
0.01
0.01 10 1000
OUTPUT NOISE SPECTRAL DENSITY
vs. FREQUENCY
0.1
1
MAX8869-09
FREQUENCY (kHz)
NOISE (μV/√Hz)
0.1 1100
IOUT = 250mA
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
_______________________________________________________________________________________
5
0
0.001 10.10.01
OUTPUT NOISE
vs. OUTPUT CURRENT
60
20
140
100
180
80
40
160
120
MAX8869-10
OUTPUT CURRENT (A)
OUTPUT NOISE (µVRMS)
200μs/div
LINE-TRANSIENT RESPONSE
MAX8869-11
VIN
VOUT
5V
3.6V
10mV/div
AC-COUPLED
IOUT = 250mA
20μs/div
LOAD-TRANSIENT RESPONSE
MAX8869-12
IOUT
VOUT
1A
100mA
50mV/div
AC-COUPLED
20μs/div
LOAD-TRANSIENT RESPONSE
MAX8869-13
IOUT
VOUT
3A
10mA
200mV/div
AC-COUPLED
4ms/div
1MHz BANDWIDTH
OUTPUT NOISE
MAX8869-14
100μV/div
IOUT = 100µA
40µs/div
SHUTDOWN RESPONSE
MAX8869-15
5V/div
VOUT
VSHDN
2V/div
10ms/div
SOFT-START RESPONSE
MAX8869-16
5V/div
CSS = 100nF
IIN
2V/div
VOUT
1A/div
VSHDN
1ms/div
RESET OUTPUT RESPONSE
MAX8869-17
5V/div
VIN
VOUT
2V/div
RST
2V/div
RST
OUTPUT
DELAY
Typical Operating Characteristics (continued)
(VIN = +5V, VOUT = +2.5V, SHDN = IN, SS = open, COUT = 1µF, TA= +25°C, unless otherwise noted.)
MAX8869
Detailed Description
The MAX8869 features Dual Mode operation, allowing a
fixed output of +5V, +3.3V, +2.5V, +1.8V, or +1.0V, or
adjustable output from +0.8V to +5.0V. The regulators
are guaranteed to supply 1A of continuous output cur-
rent with only 1µF of output capacitance.
As shown in the functional diagram (Figure 1), the
device has a 0.8V reference, error amplifier, MOSFET
driver, P-channel pass transistor, internal feedback
voltage-divider, soft-start function, reset timer, and Dual
Mode and low VOUT comparators.
The 0.8V reference is connected to the error amplifier’s
inverting input. The error amplifier compares this refer-
ence with the selected feedback voltage and amplifies
the difference. The MOSFET driver reads the error sig-
nal and applies the appropriate drive to the P-channel
transistor. If the feedback voltage is high, the pass tran-
sistor’s gate is pulled up, allowing less current to pass
to the output. The low VOUT comparator senses when
the feedback voltage has dropped 8% below its
expected level, causing RST to go low.
The output voltage is fed back through either an inter-
nal resistor-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 80mV, the internal feedback path
is used and the output voltage is regulated to the facto-
ry-preset voltage. Otherwise, the output voltage is set
with the external resistor-divider.
Internal P-Channel Pass Transistor
The MAX8869 features a 1A P-channel MOSFET pass
transistor. Unlike similar designs using PNP pass tran-
sistors, 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. The MAX8869 does not suf-
fer from these problems and consumes only 500µA of
quiescent current even in dropout.
1A, Microcap, Low-Dropout,
Linear Regulator
6 _______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
1, 9, 16 N.C. No Connection. Not internally connected.
2, 3, 4, 5 IN
Regulator Input. Connect to power source (+2.7V to +5.5V). Bypass with 1μF or greater
capacitor to GND (see Capacitor Selection and Regulator Stability). Connect all IN inputs
together for proper operation.
6RST
Reset O utp ut. O p en- d r ai n outp ut i s l ow w hen V
OU T
i s 8% b el ow i ts nom i nal val ue. RST r em ai ns
l ow w hi l e the outp ut vol tag e ( V
OUT) i s b el ow the r eset thr eshol d and for at l east 3m s after V
OUT
r i ses to w i thi n r eg ul ati on. C onnect a 100kΩ p ul l up r esi stor to O U T to ob tai n an outp ut vol tag e.
7SHDN Active-Low Shutdown Input. A logic low reduces the supply current to 0.1μA. Connect SHDN
to IN for normal operation. In shutdown, RST is low and the soft-start capacitor discharges.
8SS
Soft-Start Control. Connect a soft-start capacitor from SS to GND (see Soft-Start Capacitor
Selection). Leave SS open to disable soft-start.
10 GND Ground. Solder both GND and EP to a large pad or to the circuit-board ground plane to
maximize power dissipation.
11 SET Voltage-Setting Input. Connect SET to GND for factory-preset output voltage. Connect SET to
an external resistor-divider for adjustable output operation.
12, 13, 14, 15 OUT Regulator Output. Bypass with a 1μF or greater low-ESR capacitor to GND (see Capacitor
Selection and Regulator Stability). Connect all OUT outputs together for proper operation.
—EP
Exposed Pad. Connect to a large ground plane to maximize thermal performance. Not
intended as an electrical connection point.
Output Voltage Selection
The MAX8869 features Dual Mode operation. Connect
SET to GND (Figure 2) for preset voltage mode (see
Ordering Information
). In adjustable mode, set the out-
put between +0.8V to +5.0V through two external resis-
tors connected as a voltage-divider to SET (Figure 3).
The output voltage is set by the following equation:
VOUT = VSET (1 + R1 / R2)
where VSET = +0.8V. To simplify resistor selection:
R1 = R2 (VOUT / VSET - 1)
Since the input bias current at SET is nominally 50nA,
large resistance values can be used for R1 and R2 to
minimize power consumption without losing efficiency.
Up to 80kΩis acceptable for R2.
In preset voltage mode, the impedance between SET
and ground should be less than 10kΩ. Otherwise, spu-
rious conditions could cause the voltage at SET to
exceed the 80mV Dual Mode threshold.
Shutdown
A logic low on SHDN disables the MAX8869. In shut-
down, the pass transistor, control circuitry, reference,
and all biases are turned off, reducing supply current to
typically 0.1µA. Connect SHDN to IN for normal opera-
tion. In shutdown, RST is low and the soft-start capaci-
tor is discharged.
RST
Comparator
The MAX8869 features a low VOUT indicator that
asserts when the output voltage falls out of regulation.
The open-drain RST goes low when OUT falls 8%
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
_______________________________________________________________________________________ 7
Figure 1. Functional Diagram
Figure 2. Typical Operating Circuit with Preset Output Voltage
MOSFET DRIVER
WITH FOLDBACK
CURRENT LIMIT
SHUTDOWN
LOGIC
0.8V
REFERENCE
SS
GND
SHDN
IN
OUT
RST
SET
VSS
6μA
736mV
THERMAL
SENSOR
OUT
DELAY TIMER
IN
3ms
SHUTDOWN
ERROR AMP
DUAL MODE
COMPARATOR
80mV
92% VOUT
DETECTOR
VSS
PMOS
NMOS
R1
R2
MAX8869
IN
IN
IN
IN
SHDN
SS
OUT
OUT
OUT
OUT
RST
SET
GND
ON
OFF
COUT
1µF
CIN
1µF
CSS
VOUT
VIN
RESET
OUTPUT
MAX8869
MAX8869
below its nominal output voltage. RST remains low for
3ms after OUT has returned to its nominal value. A
100kΩpullup resistor from RST to a suitable logic sup-
ply voltage (typically OUT) provides a logic control sig-
nal. RST can be used as a power-on-reset signal to a
microcontroller (µC) or can drive an external LED for
indicating a power failure. RST is low during shutdown.
RST remains valid for an input voltage as low as 1V.
Soft-Start
As shown in Figure 4, a capacitor on SS allows a grad-
ual buildup of the MAX8869 output, reducing the initial
in-rush current peaks at startup. When SHDN is driven
low, the soft-start capacitor is discharged. When SHDN
is driven high or power is applied to the device, a con-
stant 6µA current charges the soft-start capacitor. The
resulting linear ramp voltage on SS increases the cur-
rent-limit comparator threshold, limiting the P-channel
gate drive (see
Soft-Start Capacitor Selection
). Leave
SS unconnected to disable the soft-start feature.
Current Limiting
The MAX8869 features a 4A current limit when the out-
put voltage is in regulation. When the output voltage
drops by 8% below its nominal, the current limit folds
back to 1.7A. The output can be shorted to ground for
an indefinite period of time without damaging the
device. Avoid continuous output current of more than
1A to prevent damage.
Both the in-regulation and short-circuit current limits can
be reduced from their nominal values by reducing the
voltage at the soft-start input (SS) below 1.25V. The cur-
rent limits scale proportionately with the voltage by ILIM
= ILIM_NOM (VSS / 1.25). Since the SS input sources a
nominal 6µA current, the current limit can be set by
tying a resistor (RSS) between SS and GND, so that ILIM
= ILIM_NOM (ISS RSS / 1.25) where ISS = 6µA . With
RSS in place, soft-start can still be achieved by placing
a capacitor (CSS) in parallel with RSS. The output current
now ramps up asymptotically to the reduced current
limit rather than the nominal one, increasing the soft-
start time. The time required for the current limit to reach
90% of its steady-state value is given by tSS = 2.3
RSSCSS.
Thermal Overload Protection
Thermal overload protection limits total power dissipa-
tion in the MAX8869. When the junction temperature
exceeds TJ= +170°C, the thermal sensor turns off the
pass transistor, allowing the IC to cool. The thermal sen-
sor turns the pass transistor on once the IC’s junction
temperature drops approximately 20°C. Continuous
short-circuit conditions will consequently result in a
pulsed output.
Thermal overload protection is designed to safeguard
the MAX8869 in the event of fault conditions. For con-
tinuous operation, do not exceed the absolute maxi-
mum junction temperature rating of TJ= +150°C.
Operating Region and Power Dissipation
Maximum power dissipation of the MAX8869 depends
on the thermal resistance of the case and circuit board,
the temperature difference between the die junction
and ambient air, and the rate of air flow. The power dis-
sipation across the device is P = IOUT (VIN - VOUT). The
resulting maximum power dissipation is:
PMAX = [(TJ(MAX) - TA) / (θJC + θCA)]
where (TJ(MAX) - TA) is the temperature difference
between the maximum allowed die junction (150°C)
and the surrounding air; θJC (junction
1A, Microcap, Low-Dropout,
Linear Regulator
8 _______________________________________________________________________________________
Figure 3. Typical Operating Circuit with Adjustable Output
Voltage
IN
IN
IN
IN
SHDN
SS GND
OUT
OUT
OUT
OUT
RST
SET
ON OFF
COUT
1μF
CIN
1μF
VOUT
VIN
RESET
OUTPUT
MAX8869
R1
R2
Figure 4. Typical Operating Circuit with Soft-Start and Current-
Limit Reduction
IN
IN
IN
IN
SHDN
SS
OUT
OUT
OUT
OUT
RST
SET
GND
ON OFF
COUT
1μF
CIN
1μF
VOUT
VIN
RESET
OUTPUT
MAX8869
CSS RSS
to case) is the thermal resistance of the package cho-
sen, and θCA is the thermal resistance from the case
through the PC board, copper traces, and other materi-
als to the surrounding air. Figure 5 shows the allowable
power dissipation for typical PC boards at +25°C,
+50°C, and +70°C ambient temperatures.
The MAX8869 TSSOP-EP package features an
exposed thermal pad on its underside. This pad lowers
the package’s thermal resistance by providing a direct
thermal heat path from the die to the PC board.
Additionally, GND also channels heat. Connect the
exposed thermal pad and GND to circuit ground by
using a large pad (1in2minimum recommended) or
multiple vias to the ground plane.
Applications Information
Capacitor Selection and
Regulator Stability
Capacitors are required at the MAX8869 input and out-
put. Connect 1µF or greater capacitors between IN and
GND (CIN) and OUT and GND (COUT). Due to the
MAX8869’s relatively high bandwidth, use only surface-
mount ceramic capacitors that have low equivalent
series resistance (ESR) and high self-resonant frequen-
cy (SRF). Make the input and output traces at least
2.5mm wide (the width of the four parallel inputs and
outputs), and connect CIN and COUT within 6mm of the
IC to minimize the impact of PC board trace induc-
tance. The width of the ground trace should be maxi-
mized underneath the IC to ensure a good connection
between GND and the ground side of the capacitors.
The output capacitor’s ESR and SRF can affect stability
and output noise. Use capacitors with greater than 5MHz
SRF and ESR of 60mΩor less to ensure stability and
optimum transient response. This is particularly true in
applications with very low output voltage (<2V) and high
output current (>0.5A).
Since some capacitor dielectrics may vary over bias
voltage and temperature, consult the capacitor manu-
facturer specifications to ensure that the capacitors
meet these requirements over all voltage and tempera-
ture conditions used.
Soft-Start Capacitor Selection
A capacitor (CSS) connected from SS to GND causes
the MAX8869 output current to slowly rise during start-
up, reducing stress on the input supply. The rise time to
full current limit (tSS) is determined by:
tSS = 2.08 10-4 CSS
where CSS is in nF. Typical capacitor values between
10nF to 100nF, with a 5V rating, are sufficient.
Because this ramp is applied to the current-limit com-
parator, the actual time for the output voltage to ramp
up depends on the load current and output capacitor.
Leave SS open to disable soft-start.
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. Since
a 0.2ΩP-channel MOSFET is used as the pass device,
dropout voltage is the product of RDS(ON) and load
current (see
Electrical Characteristics
and Dropout
Voltage vs. Output Current in
Typical Operating
Characteristics
). The MAX8869 operating current
remains low in dropout.
Noise, PSRR, and Transient Response
The MAX8869 is designed to achieve low dropout volt-
age and low quiescent current in battery-powered sys-
tems while still maintaining good noise, transient
response, and AC rejection (see PSRR vs. Frequency
in the
Typical Operating Characteristics)
. When operat-
ing from very noisy sources, supply noise rejection and
transient response can be improved by increasing the
values of the input and output capacitors and employ-
ing passive postfiltering. MAX8869 output noise is typi-
cally 150µVRMS. (see the Output Noise plot in the
Typical Operating Characteristics)
.
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
_______________________________________________________________________________________ 9
Figure 5. Power Operating Region: Maximum Output Current
vs. Input-Output Differential Voltage
0
0.6
0.4
0.2
0.8
1.0
1.2
103245
INPUT-OUTPUT DIFFERENTIAL VOLTAGE
MAXIMUM OUTPUT CURRENT (A)
MAXIMUM CONTINUOUS CURRENT
TYPICAL SUPPLY VOLTAGE LIMIT
TA = +70°C
TA = +50°C
TA = +25°C
TJ = +150°C
TYPICAL DROPOUT
VOLTAGE LIMIT
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
10 ______________________________________________________________________________________
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.
16 TSSOP U16E+3 21-0108 90-0120
Chip Information
PROCESS: BiCMOS
1A, Microcap, Low-Dropout,
Linear Regulator
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________
11
© 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 8/00 Initial release —
1 6/10
Added lead-free versions to Ordering Information, updated Continuous
Power Dissipation and added Soldering Temperature to Absolute Maximum
Ratings, and added EP row to Pin Description
1, 2, 6
