MAX8869 - Maxim Integrated
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
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 highaccuracy (±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 guaranteed stability. An internal PMOS pass transistor allows
low 500µA supply current, making this regulator useful
for networking and telecom hardware as well as battery-operated equipment. Other features include softstart, 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.
Features
o
o
o
o
Guaranteed 1A Output Current
Stable with COUT = 1µF
Low 200mV Dropout at 1A
±1% Output Voltage Accuracy
Preset at +5V, +3.3V, +2.5V, +1.8V, or +1.0V
and Adjustable from +0.8V to +5.0V
o 54dB PSRR at 100kHz
o
o
o
o
o
Adjustable Soft-Start
3ms Reset Output
Foldback Output Current Limit
Thermal Overload Protection
High-Power 16-Pin TSSOP Package (1.5W)
30% Smaller than SOT223 (Only 1.1mm High)
Ordering Information
PART
________________________Applications
PIN-PACKAGE
VOUT (V)*
MAX8869EUE50+
16 TSSOP-EP**
+5.0
+3.3
MAX8869EUE33+
16 TSSOP-EP**
Telecom Hardware
MAX8869EUE25+
16 TSSOP-EP**
+2.5
Network Equipment
MAX8869EUE25/V+
16 TSSOP-EP**
+2.5
Mobile Phone Base Stations
MAX8869EUE18+
16 TSSOP-EP**
+1.8
Personal Computers
MAX8869EUE10+
16 TSSOP-EP**
Notebook Computers
Microcap is a registered trademark of American Technical
Ceramics Corp.
+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.
/V denotes an automotive qualified part.
Pin Configuration
Typical Operating Circuit
TOP VIEW
+
MAX8869
VIN
+2.7V TO +5.5V
1µF
ON
OFF
IN
OUT
IN
OUT
IN
OUT
IN
OUT
SHDN
RST
SS
SET
GND
VOUT
UP TO 1A
1µF
RESET
OUTPUT
N.C. 1
16 N.C.
IN 2
15 OUT
14 OUT
IN 3
IN 4
MAX8869
13 OUT
IN 5
12 OUT
RST 6
11 SET
SHDN 7
10 GND
9
SS 8
N.C.
TSSOP-EP
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-1692; Rev 2; 10/12
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
ABSOLUTE MAXIMUM RATINGS
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
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.
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.)
PARAMETER
Input Voltage Range
SYMBOL
CONDITIONS
VIN
MIN
TYP
2.7
Input Undervoltage Lockout
Typical hysteresis = 50mV
Output Voltage Accuracy
IOUT = 1mA, TA = +85°C
SET Regulation Voltage
(Adjustable Mode)
IOUT = 150mA, TA = +85°C
Line Regulation
∆VLNR
VIN = VOUT + 0.5V to +5.5V, IOUT = 10mA
Load Regulation
Adjustable Output Voltage Range
∆VLDR
IOUT = 1mA to 1A
2.35
2.45
-1
792
800
MAX
UNITS
5.5
V
2.55
V
1
%
808
mV
0.1
0.8
0.8
%/V
1.5
5
%/A
V
Maximum Output Current
IOUT
Continuous
1
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
40
80
120
mV
VSET = +0.9V
50
300
nA
IOUT = 100µA
0.5
2.0
IOUT = 1A
2.5
SET Dual Mode Threshold
SET Input Bias Current
Ground Current
ISET
IGND
ARMS
Dropout Voltage
(Note 1)
IOUT = 1mA, +2.7V < VIN < +5.5V
0.2
IOUT = 1A, VOUT = +3.3V (Note 2)
200
Output Voltage Noise
f = 10Hz to 1MHz, COUT = 1µF, IOUT = 150mA
150
Power-Supply Rejection Ratio
Shutdown Supply Current
SHDN Input Threshold
PSRR
IOFF
VIH
VIL
SHDN Input Bias Current
Soft-Start Charge Current
ISS
f = 100kHz, COUT = 1µF
54
SHDN = GND, VIN = +5.5V, VOUT = 0
0.1
+2.7V < VIN < +5.5V
SHDN = GND or IN
0
6
ISINK = 1mA
IN Operating Voltage Range for
RST Valid
ISINK = 10µA
RST Leakage
V RST = +5.5V
RST Trip Level Referred to
Nominal VOUT
Falling edge, typical hysteresis = 10mV
89
Rising edge
1
Thermal Shutdown Threshold
2
TSHDN
Typical thermal hysteresis = +20°C
Dual Mode is a trademark of Maxim Integrated Products.
dB
10
0.6
VSS = 0V
mV
µVRMS
1.6
RST Output Low Voltage
RST Release Delay
350
mA
0.1
µA
V
µA
µA
0.1
V
5.5
V
0.01
1
µA
92
95
% OUT
3
5.5
ms
1.0
+170
o
C
Maxim Integrated
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
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)
PARAMETER
Input Voltage Range
SYMBOL
CONDITIONS
VIN
MIN
MAX
UNITS
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
2.0
%/A
Load Regulation
∆VLDR
IOUT = 1mA to 1A
Adjustable Output Voltage Range
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
SET Dual Mode Threshold
40
SET Input Bias Current
ISET
Ground Current
IGND
Dropout Voltage (Note 1)
Shutdown Supply Current
SHDN Input Threshold
IOFF
VIH
VIL
VSET = +0.9V
A
120
mV
300
nA
IOUT = 100µA
2.0
mA
IOUT = 1A, VOUT = +3.3V (Note 2)
350
mV
10
µA
SHDN = GND, VIN = +5.5V, VOUT = 0V
+2.7V < VIN < +5.5V
1.7
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
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
1.0
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.
Maxim Integrated
3
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
Typical Operating Characteristics
(VIN = +5V, VOUT = +2.5V, SHDN = IN, SS = open, COUT = 1µF, TA = +25°C, unless otherwise noted.)
OUTPUT VOLTAGE DEVIATION
vs. TEMPERATURE
-1.0
-1.5
-2.0
VIN = +3V
-2.5
IOUT = 250mA
0.5
0
-0.5
-1.0
0.5
1.0
1.5
2.0
2.5
-15
10
35
60
85
0
1
2
3
4
5
GROUND CURRENT
vs. TEMPERATURE
DROPOUT VOLTAGE
vs. OUTPUT CURRENT
GROUND CURRENT (mA)
VIN = +3V
1.5
1.0
2.0
IOUT = 250mA
1.5
VIN = +5V
VIN = +3V
1.0
0.5
450
VOUT = +3.3V
400
DROPOUT VOLTAGE (mV)
MAX8869-04
VIN = +5V
2.5
2.0
2.5
MAX8869-06
GROUND CURRENT
vs. OUTPUT CURRENT
350
300
250
200
150
100
IOUT = 0V
50
0
0
0
400
600
800
1000
-40
-15
10
35
60
0
85
250
500
750
1000
1250
1500
TEMPERATURE (°C)
OUTPUT CURRENT (mA)
DROPOUT VOLTAGE
vs. INPUT VOLTAGE
PSRR vs. FREQUENCY
OUTPUT NOISE SPECTRAL DENSITY
vs. FREQUENCY
IOUT = 500mA
IN DROPOUT, VOUT ≅ VIN
60
10
MAX8869-09
OUTPUT CURRENT (mA)
MAX8869-08
200
MAX8869-07
0
IOUT = 250mA
150
40
30
100
20
50
10
0
0
2.5
3.0
3.5
4.0
INPUT VOLTAGE (V)
4.5
5.0
NOISE (µV/√Hz)
50
200
PSRR (dB)
DROPOUT VOLTAGE (mV)
IOUT = 0A
INPUT VOLTAGE (V)
0.5
4
1.0
TEMPERATURE (∞C)
3.0
250
1.5
OUTPUT CURRENT (A)
3.5
300
2.0
0
-40
3.0
IOUT = 0.5A
2.5
0.5
MAX8869-05
0
IOUT = 1A
3.0
-1.5
-3.0
GROUND CURRENT (mA)
1.0
GROUND CURRENT (mA)
VIN = +5V
3.5
MAX8869-02
-0.5
1.5
OUTPUT VOLTAGE DEVIATION (%)
MAX8869-01
OUTPUT VOLTAGE DEVIATION (%)
0
GROUND CURRENT
vs. INPUT VOLTAGE
MAX8869-03
OUTPUT VOLTAGE DEVIATION
vs. OUTPUT CURRENT
IOUT = 300mA
0.01
0.1
1
0.1
0.01
1
10
FREQUENCY (kHz)
100
1000
0.01
0.1
1
10
100
1000
FREQUENCY (kHz)
Maxim Integrated
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
Typical Operating Characteristics (continued)
(VIN = +5V, VOUT = +2.5V, SHDN = IN, SS = open, COUT = 1µF, TA = +25°C, unless otherwise noted.)
OUTPUT NOISE
vs. OUTPUT CURRENT
LINE-TRANSIENT RESPONSE
MAX8869-10
160
OUTPUT NOISE (µVRMS)
LOAD-TRANSIENT RESPONSE
MAX8869-11
180
MAX8869-12
5V
VIN
140
1A
IOUT
100mA
3.6V
120
100
80
VOUT
60
50mV/div
AC-COUPLED
VOUT
10mV/div
AC-COUPLED
40
20
IOUT = 250mA
0
0.001
0.01
0.1
1
200µs/div
20µs/div
OUTPUT CURRENT (A)
LOAD-TRANSIENT RESPONSE
OUTPUT NOISE
SHUTDOWN RESPONSE
MAX8869-13
MAX8869-14
MAX8869-15
1MHz BANDWIDTH
IOUT = 100µA
3A
IOUT
10mA
VSHDN
5V/div
VOUT
2V/div
100µV/div
200mV/div
AC-COUPLED
VOUT
20µs/div
4ms/div
40µs/div
RESET OUTPUT RESPONSE
SOFT-START RESPONSE
MAX8869-17
MAX8869-16
VSHDN
5V/div
VIN
5V/div
1A/div
IIN
VOUT
VOUT
2V/div
2V/div
RST
OUTPUT
DELAY
2V/div
RST
CSS = 100nF
10ms/div
Maxim Integrated
1ms/div
5
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
Pin Description
PIN
NAME
FUNCTION
1, 9, 16
N.C.
2, 3, 4, 5
IN
6
RST
Reset Output. Open-drain output is low when VOUT is 8% below its nominal value. RST remains
low while the output voltage (VOUT) is below the reset threshold and for at least 3ms after VOUT
rises to within regulation. Connect a 100kΩ pullup resistor to OUT to obtain an output voltage.
7
SHDN
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.
8
SS
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
No Connection. Not internally connected.
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.
Soft-Start Control. Connect a soft-start capacitor from SS to GND (see Soft-Start Capacitor
Selection). Leave SS open to disable soft-start.
Exposed Pad. Connect to a large ground plane to maximize thermal performance. Not
intended as an electrical connection point.
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 current 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 reference with the selected feedback voltage and amplifies
the difference. The MOSFET driver reads the error signal and applies the appropriate drive to the P-channel
transistor. If the feedback voltage is high, the pass transistor’s gate is pulled up, allowing less current to pass
to the output. The low VOUT comparator senses when
6
the feedback voltage has dropped 8% below its
expected level, causing RST to go low.
The output voltage is fed back through either an internal 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 factory-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 transistors, P-channel MOSFETs require no base drive,
which reduces quiescent current. PNP-based regulators also waste considerable current in dropout when
the pass transistor saturates and use high base-drive
currents under large loads. The MAX8869 does not suffer from these problems and consumes only 500µA of
quiescent current even in dropout.
Maxim Integrated
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
IN
SHUTDOWN
THERMAL
SENSOR
MAX8869
ERROR AMP
SHUTDOWN
LOGIC
SHDN
MOSFET DRIVER
WITH FOLDBACK
CURRENT LIMIT
PMOS
VSS
OUT
92% VOUT
DETECTOR
DELAY TIMER
IN
RST
736mV
3ms
NMOS
OUT
0.8V
REFERENCE
SET
R1
6µA
DUAL MODE
COMPARATOR
VSS
SS
80mV
R2
GND
Figure 1. Functional Diagram
where VSET = +0.8V. To simplify resistor selection:
MAX8869
VIN
CIN
1µF
ON
OFF
CSS
IN
OUT
IN
OUT
IN
OUT
IN
OUT
SHDN
RST
SS
SET
GND
COUT
1µF
VOUT
RESET
OUTPUT
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 80kΩ is acceptable for R2.
In preset voltage mode, the impedance between SET
and ground should be less than 10kΩ. Otherwise, spurious conditions could cause the voltage at SET to
exceed the 80mV Dual Mode threshold.
Shutdown
Figure 2. Typical Operating Circuit with Preset Output Voltage
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 output between +0.8V to +5.0V through two external resistors connected as a voltage-divider to SET (Figure 3).
The output voltage is set by the following equation:
VOUT = VSET (1 + R1 / R2)
Maxim Integrated
A logic low on SHDN disables the MAX8869. In shutdown, 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 operation. In shutdown, RST is low and the soft-start capacitor is discharged.
RST Comparator
The MAX8869 features a low V OUT indicator that
asserts when the output voltage falls out of regulation.
The open-drain RST goes low when OUT falls 8%
7
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
MAX8869
VIN
CIN
1µF
ON
OFF
MAX8869
IN
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
SHDN
RST
SHDN
RST
SS
SET
GND
SS
R1
COUT
1µF
VOUT
RESET
OUTPUT
VIN
CIN
1µF
ON
OFF
SET
GND
CSS
RSS
COUT
1µF
VOUT
RESET
OUTPUT
R2
Figure 3. Typical Operating Circuit with Adjustable Output
Voltage
Figure 4. Typical Operating Circuit with Soft-Start and CurrentLimit Reduction
below its nominal output voltage. RST remains low for
3ms after OUT has returned to its nominal value. A
100kΩ pullup resistor from RST to a suitable logic supply voltage (typically OUT) provides a logic control signal. 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.
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 softstart time. The time required for the current limit to reach
90% of its steady-state value is given by t SS = 2.3
RSSCSS.
Soft-Start
As shown in Figure 4, a capacitor on SS allows a gradual 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 constant 6µA current charges the soft-start capacitor. The
resulting linear ramp voltage on SS increases the current-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 output 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 current 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
8
Thermal Overload Protection
Thermal overload protection limits total power dissipation 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 sensor 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 continuous operation, do not exceed the absolute maximum 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 dissipation across the device is P = IOUT (VIN - VOUT). The
resulting maximum power dissipation is:
PMAX = [(TJ(MAX) - TA) / (θJC + θCA)]
where (T J(MAX) - T A ) is the temperature difference
between the maximum allowed die junction (150°C)
and the surrounding air; θJC (junction to case) is the
Maxim Integrated
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
SRF and ESR of 60mΩ or 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).
1.2
1.0
0.6
0.4
TYPICAL SUPPLY VOLTAGE LIMIT
TA = +25°C
0.8
TYPICAL DROPOUT
VOLTAGE LIMIT
MAXIMUM OUTPUT CURRENT (A)
MAXIMUM CONTINUOUS CURRENT
TA = +50°C
TA = +70°C
0.2
TJ = +150°C
Since some capacitor dielectrics may vary over bias
voltage and temperature, consult the capacitor manufacturer specifications to ensure that the capacitors
meet these requirements over all voltage and temperature conditions used.
Soft-Start Capacitor Selection
0
0
1
2
3
4
5
INPUT-OUTPUT DIFFERENTIAL VOLTAGE
Figure 5. Power Operating Region: Maximum Output Current
vs. Input-Output Differential Voltage
thermal resistance of the package chosen, and θCA is
the thermal resistance from the case through the PC
board, copper traces, and other materials 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 (1in2 minimum recommended) or
multiple vias to the ground plane.
Applications Information
Capacitor Selection and
Regulator Stability
Capacitors are required at the MAX8869 input and output. Connect 1µF or greater capacitors between IN and
GND (C IN ) and OUT and GND (C OUT ). Due to the
MAX8869’s relatively high bandwidth, use only surfacemount ceramic capacitors that have low equivalent
series resistance (ESR) and high self-resonant frequency (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 inductance. The width of the ground trace should be maximized 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
Maxim Integrated
A capacitor (CSS) connected from SS to GND causes
the MAX8869 output current to slowly rise during startup, 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 comparator, 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 differential (dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this
determines the useful end-of-life battery voltage. Since
a 0.2Ω P-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 voltage and low quiescent current in battery-powered systems while still maintaining good noise, transient
response, and AC rejection (see PSRR vs. Frequency
in the Typical Operating Characteristics). When operating from very noisy sources, supply noise rejection and
transient response can be improved by increasing the
values of the input and output capacitors and employing passive postfiltering. MAX8869 output noise is typically 150µV RMS. (see the Output Noise plot in the
Typical Operating Characteristics).
9
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
Package Information
Chip Information
PROCESS: BiCMOS
10
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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
Maxim Integrated
MAX8869
1A, Microcap, Low-Dropout,
Linear Regulator
Revision History
REVISION
NUMBER
REVISION
DATE
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
2
10/12
Added automotive qualified part to Ordering Information
DESCRIPTION
PAGES
CHANGED
—
1, 2, 6
1
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 ________________________________ 11
© 2012 Maxim Integrated Products, Inc.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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