19-0516; Rev 1; 9/08
KIT
ATION
EVALU
E
L
B
AVAILA
Dual 300mA Pin-Programmable LDO
Linear Regulators
The MAX8633–MAX8636 offer low-dropout (LDO) voltage and ultra-low-power regulation in a subminiaturized
2mm x 2mm µDFN package. The devices operate from
a 2.7V to 5.5V supply and deliver up to 300mA from
each output, with a typical dropout voltage of 90mV at
100mA load current. Each device is designed with
internal p-channel MOSFET pass transistors to ensure a
low-quiescent supply current of 54µA (typical, both
LDOs on). Other features include low-noise operation
(MAX8634/MAX8636), output current limiting, and thermal shutdown.
The MAX8633 features an open-drain, active-low
RESET output to monitor OUT2, eliminating external
components and adjustments. The MAX8633 asserts a
RESET signal (120ms minimum timeout) when VOUT2
drops below 87% of the nominal output voltage. The
MAX8634/MAX8636 feature a noise bypass input to the
internal reference for low output noise (45µVRMS typ).
The MAX8634/MAX8635 provide independent SHDN
inputs for disabling the regulators, while the MAX8633/
MAX8636 provide a single SHDN input for disabling
both regulators.
The MAX8633/MAX8635/MAX8636 have two logic
inputs that select one of nine preset output-voltage
combinations, eliminating external 1% resistors, as well
as inventory burden. The MAX8634 has one logic input
to select three output-voltage options.
The MAX8633–MAX8636 are available in an 8-pin, 2mm
x 2mm µDFN package for minimizing footprint, and an
8-pin, 3mm x 3mm TDFN package for higher power dissipation. The devices are specified over the extended
temperature range (-40°C to +85°C). All packages are
lead free.
Applications
Cellular and Cordless Phones
Features
♦ Pin-Programmable Output Voltages
♦ 300mA Output Current
♦ Low 90mV Dropout at 100mA Load
♦ Open-Drain, Active-Low RESET (MAX8633)
♦ Low 45µVRMS Output Noise (MAX8634/MAX8636)
♦ Low 54µA Quiescent Supply Current
♦ Low < 1µA Maximum Shutdown Current
♦ Output Current Limit
♦ Thermal Shutdown
Ordering Information
PINPACKAGE
TOP
MARK
MAX8633ELA+ -40°C to +85°C
8 µDFN
2mm x 2mm
AAH
MAX8633ETA+ -40°C to +85°C
8 TDFN
3mm x 3mm
AOQ
MAX8634ELA+ -40°C to +85°C
8 µDFN
2mm x 2mm
AAI
PART
TEMP RANGE
+Denotes a lead-free/RoHS-compliant package.
Ordering Information continued at end of data sheet.
Typical Operating Circuits
INPUT
2.7V TO 5.5V
IN
OUT1
CIN
2.2μF
COUT1
2.2μF
PDAs and Digital Cameras
MAX8633 OUT2
Small LCD Displays
Notebook Computers
COUT2
2.2μF OUT2
P1
Wireless LAN Cards
Handheld Instruments
P2
RESET
SHDN
GND
Pin Configurations and Selector Guide appear at end of
data sheet.
Typical Operating Circuits continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX8633–MAX8636
General Description
MAX8633–MAX8636
Dual 300mA Pin-Programmable LDO
Linear Regulators
ABSOLUTE MAXIMUM RATINGS
(All voltages refer to GND, unless otherwise noted.)
IN ...........................................................................-0.3V to +6.0V
SHDN, SHDN1, SHDN2, RESET,
P, P1, P2, BP, OUT1, OUT2 .....................-0.3V to (VIN + 0.3V)
Continuous Output Short-Circuit Duration..................Continuous
Continuous Power Dissipation (TA = +70°C)
8-Pin µDFN 2mm x 2mm
(derate 4.8mW/°C above +70°C) .................................380mW
8-Pin TDFN 3mm x 3mm
(derate 23.8mW/°C above +70°C) .............................1904mW
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
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 = 3.7V, SHDN = SHDN1 = SHDN2 = IN, P = P1 = P2 = GND, CIN = 2.2µF, COUT1 = 2.2µF, COUT2 = 2.2µF, CBP = 0.01µF, TA =
-40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
Input Voltage
Input Undervoltage
Lockout
Ground Current
Shutdown Supply
Current
SYMBOL
CONDITIONS
MAX
UNITS
5.5
V
2.25
2.35
V
IOUT_ = 0mA
54
75
IOUT_ = 100mA
60
IOUT_ = 10mA, dropout (Note 2)
60
VIN
VUVLO
IQ
IOFF
MIN
TYP
2.7
VIN rising; hysteresis = 95mV (typ)
SHDN_ = GND
2.15
TA = +25°C
0.005
TA = +85°C
0.01
µA
1
µA
OUT1, OUT2
IOUT_ = 70mA; TA = +25°C
Output Voltage
Accuracy (for Any
Output Voltage)
Current Limit
Drop-Out Voltage
ILIM
VIN - VOUT
2
+0.7
-1
+1
IOUT_ = 0.1mA to 300mA; VIN = (VOUT_ + 0.5V) to
5.5V
-1.8
+1.7
OUT_ = 0V
400
VOUT_ = 2.8V (MAX8633);
VOUT_ = 2.85V (MAX8634/MAX8635/MAX8636);
IOUT_ = 100mA (Note 2)
f = 10Hz to 100kHz;
IOUT_ = 10mA
Output Noise
Output AC PowerSupply Rejection
Ratio
-0.7
IOUT_ = 70mA
PSRR
%
500
600
mA
90
200
mV
MAX8633
MAX8635
450
MAX8634
MAX8636
45
f < 1kHz
60
f < 10kHz
55
µVRMS
IOUT_ = 30mA
dB
_______________________________________________________________________________________
Dual 300mA Pin-Programmable LDO
Linear Regulators
(VIN = 3.7V, SHDN = SHDN1 = SHDN2 = IN, P = P1 = P2 = GND, CIN = 2.2µF, COUT1 = 2.2µF, COUT2 = 2.2µF, CBP = 0.01µF, TA =
-40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SHUTDOWN INPUTS (SHDN, SHDN1, AND SHDN2)
Input Voltage High
VIH
VIN = 2.7V to 5.5V
Input Voltage Low
VIL
VIN = 2.7V to 5.5V
Input Bias Current
ISHDN_
VIN = 2.7V to 5.5V;
VSHDN_ = GND or IN
1.5
0.5
TA = +25°C
0.1
TA = +85°C
1
From SHDN = high to 87% of VOUT_;
IOUT_ = 70mA
Turn-On Delay
1000
90
V
nA
µs
TRI-LEVEL INPUTS (P, P1, P2)
Termination
Resistance to IN or
GND for Setting High,
Open, and Low States
IN = 2.7 to 5.5V
Input Load
Capacitance for
Open State
Design guide only
For high or low state
1
kΩ
For open state
100
50
pF
90
%
RESET
RESET High
Threshold
Percent of nominal OUT2; OUT2 rising
RESET Threshold
Hysteresis
Percent of nominal OUT2; OUT2 falling
4.5
IRESET = 20µA; VIN = 1.0V
10
100
IRESET = 500µA; VIN = 3.7V
5
100
TA = +25°C
0.1
300
TA = +85°C
1
RESET Output
Voltage Low
RESET Output High
Leakage Current
ILEAK
RESET Delay
tRP
VRESET = VIN = 5.5V
From OUT2 rising to RESET rising
84
120
87
150
%
180
mV
nA
ms
THERMAL PROTECTION
Thermal-Shutdown
Threshold
TSHDN
+165
°C
Thermal-Shutdown
Hysteresis
ΔTSHDN
15
°C
Note 1: All units are 100% tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2: The dropout voltage is defined as VIN - VOUT_ when VOUT_ drops by 100mV from VOUT_ when measured at VIN = +3.7V.
Note 3: Connect P_ to IN or GND through a resistor less than 1kΩ.
_______________________________________________________________________________________
3
MAX8633–MAX8636
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VIN = 3.8V, P = P1 = P2 = GND, IOUT1, 2 = 70mA, COUT1 = 2.2µF, COUT2 = 2.2µF, CBP = 0.01µF, CIN = 2.2µF, and TA = +25°C,
unless otherwise noted.)
50
IOUT1 = IOUT2 = 0mA
40
30
20
65
60
IOUT1 = IOUT2 = 70mA
65
SUPPLY CURRENT (μA)
SUPPLY CURRENT (μA)
60
70
MAX8633 toc02
IOUT1 = IOUT2 = 70mA
SUPPLY CURRENT (μA)
70
MAX8633 toc01
70
SUPPLY CURRENT vs. TEMPERATURE
(MAX8633ELA+)
SUPPLY CURRENT vs. LOAD CURRENT
(MAX8635ELA+)
MAX8633 toc03
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(MAX8633ELA+)
60
55
IOUT1 = IOUT2 = 0mA
50
55
45
10
P1 = P2 = IN
1
2
3
4
6
5
50
0
100
150
200
10
35
85
60
DROPOUT VOLTAGE vs. LOAD CURRENT
(MAX8633ELA+)
DROPOUT VOLTAGE vs. OUT1 VOLTAGE
(MAX8633ELA+)
OUTPUT VOLTAGE ACCURACY
vs. TEMPERATURE (MAX8633ELA+)
0.10
70
60
50
1.5
OUT1
P1 = P2 = IN
OUT1
0
50
100
150
200
250
2.65
2.70 2.75
2.80 2.85
OUT1 VOLTAGE (V)
LOAD CURRENT (mA)
PSRR vs. FREQUENCY
(MAX8636ELA+)
70
PSRR (dB)
40
30
20
10
35
60
85
OUTPUT SPECTRAL NOISE DENSITY
vs. FREQUENCY (MAX8636ELA+)
40
30
20
ROUT1 = 100Ω
P1 = IN
P2 = GND
-15
TEMPERATURE (°C)
50
0.1
-1.0
-40
10,000
NOISE DENSITY (nV/ Hz)
60
50
0.01
OUT1
-0.5
2.90 2.95
MAX8633 toc08
60
0
CHANNEL-TO-CHANNEL ISOLATION
vs. FREQUENCY (MAX8636ELA+)
MAX8633 toc07
70
0.5
-2.0
2.60
300
1.0
-1.5
40
0
MAX8633 toc06
2.0
OUT1 VOLTAGE ACCURACY (%)
DROPOUT VOLTAGE (mV)
0.15
MAX8633 toc05
MAX8633 toc04
80
0.05
OUT1
P1 = IN
P2 = GND
1000
100
10
ROUT1 = 100Ω
10
0
1
FREQUENCY (kHz)
4
-15
TEMPERATURE (°C)
0.20
0
-40
300
LOAD CURRENT (mA)
0.25
10
250
SUPPLY VOLTAGE (V)
0.30
DROPOUT VOLTAGE (V)
40
50
0
MAX8633 toc09
0
PSRR (dB)
MAX8633–MAX8636
Dual 300mA Pin-Programmable LDO
Linear Regulators
10
100
0.01
0.1
1
FREQUENCY (kHz)
10
100
0.01
0.1
1
10
FREQUENCY (kHz)
_______________________________________________________________________________________
100
1000
Dual 300mA Pin-Programmable LDO
Linear Regulators
OUTPUT NOISE DC TO 100kHz
(MAX8636ELA+)
LINE TRANSIENT RESPONSE
(MAX8633ELA+)
MAX8633 toc10
MAX8633 toc11
4.8V
VIN
1V/div
3.8V
0
50μV/div
10mV/div
AC
VOUT1
MAX8633
IOUT1 = 70mA
1ms/div
40μs/div
LOAD TRANSIENT
(MAX8633ELA+ OUT1 ILOAD = 1mA TO 70mA)
LOAD TRANSIENT NEAR DROPOUT
(VIN = VOUT + 0.1V, MAX8633ELA+ OUT1)
MAX8633 toc12
MAX8633 toc13
70mA
IOUT1
70mA
100mA/div
1mA
IOUT1
100mA/div
1mA
0
0
20mV/div
AC
VOUT1
20mV/div
AC
VOUT1
MAX8633
VIN = 3.8V
MAX8633
VIN = VOUT1 + 0.1V
40μs/div
40μs/div
RESET TIMING
(MAX8633ELA+)
OUT1 AND OUT2 TURN-ON SEQUENCE
(MAX8633ELA+)
MAX8633 toc14
MAX8633 toc15
5V/div SHDN
0
SHDN
OUT1
2V/div
OUT1
0
OUT2
2V/div
0
MAX8633
40ms/div
SHDN1
2V/div
0
0
2V/div
0
MAX8633 toc16
MAX8633
P1 = P2 = GND
IOUT1 = IOUT2 = 70mA
2V/div
RESET
EXITING SHUTDOWN
(MAX8634ELA+)
40μs/div
2V/div
0
2V/div
OUT1
SHDN2
OUT2
2V/div
0
2V/div
MAX8634
P = IN
ROUT1 = ROUT2 = 100Ω
40μs/div
_______________________________________________________________________________________
5
MAX8633–MAX8636
Typical Operating Characteristics (continued)
(VIN = 3.8V, P = P1 = P2 = GND, IOUT1, 2 = 70mA, COUT1 = 2.2µF, COUT2 = 2.2µF, CBP = 0.01µF, CIN = 2.2µF, and TA = +25°C,
unless otherwise noted.)
Dual 300mA Pin-Programmable LDO
Linear Regulators
MAX8633–MAX8636
Pin Description
PIN
MAX8633
MAX8634
1
1
MAX8635
1
MAX8636
1
NAME
IN
FUNCTION
Regulator Input. Supply voltage from 2.7V to 5.5V.
Bypass IN with a ceramic capacitor of at least 2.2µF to
GND (see the Capacitor Selection and Regulator
Stability section).
2
—
—
2
SHDN
Shutdown Input, Active Low. Drive SHDN logic low to
shut down both regulators. Connect SHDN to IN or drive
logic high for normal operation (see the Power-On
Sequence (MAX8633/Max8636 Only) section).
—
2
2
—
SHDN1
LDO1 Shutdown Input, Active Low. Drive SHDN1 logic
low to shut down OUT1. Connect SHDN1 to IN or drive
logic high for normal operation.
—
3
5
—
SHDN2
LDO2 Shutdown Input, Active Low. Drive SHDN2 logic
low to shut down OUT2. Connect SHDN2 to IN or drive
logic high for normal operation.
3
—
3
3
P2
Programming Input 2. The state of P1 and P2 selects
one of nine output-voltage options (see Tables 1, 3).
4
—
4
4
P1
Programming Input 1. The state of P1 and P2 selects
one of nine output-voltage options (see Tables 1, 3).
—
4
——
—
P
Programming Input. The state of P selects one of three
output-voltage options for the MAX8634 (see Table 2).
Reset Output, Active Low, Open Drain. RESET goes high
impedance 120ms (min) after VOUT2 rises above 87% of
the nominal output voltage. RESET is forced logic low
when VOUT2 is below 82.5% of the nominal output
voltage. Connect RESET to OUT1, OUT2, or another
voltage of VIN or lower with a pullup resistor.
5
—
—
—
RESET
—
5
—
5
BP
6
6
6
6
GND
Ground
OUT2
Regulator 2 Output. Guaranteed 300mA output current
(see the Calculating Maximum Output Power section).
Bypass OUT2 with a ceramic capacitor of at least 2.2µF
to GND (see the Capacitor Selection and Regulator
Stability section).
7
7
7
7
Reference Noise Bypass. Bypass BP to GND with a
0.01µF ceramic capacitor to reduce output noise.
8
8
8
8
OUT1
Regulator 1 Output. Guaranteed 300mA output current
(see the Calculating Maximum Output Power section).
Bypass OUT1 with a ceramic capacitor of at least 2.2µF
to GND (see the Capacitor Selection and Regulator
Stability section).
EP*
EP*
EP*
EP*
EP
Exposed Paddle. Solder the exposed paddle to a large
pad or circuit-board ground plane to increase thermal
dissipation.
*TDFN package only.
6
_______________________________________________________________________________________
Dual 300mA Pin-Programmable LDO
Linear Regulators
IN
*
SHDN
**
SHDN1
SHDN2 **
UVLO/
SHUTDOWN
AND POWER-ON
CONTROL
MOS
DRIVER
WITH ILIMIT
ERROR
AMP
THERMAL
SENSOR
OUT1
1.50V
REF
OUTPUTVOLTAGE
CONTROL
P1
P2
P
RESET
(MAX8633 ONLY)
87%
REF
(MAX8634 ONLY)
GND
DELAY
BP***
IN
OUT2
LD02
*MAX8633, MAX8636 ONLY
**MAX8634, MAX8635 ONLY
***MAX8634, MAX8636 ONLY
_______________________________________________________________________________________
7
MAX8633–MAX8636
Functional Diagram
MAX8633–MAX8636
Dual 300mA Pin-Programmable LDO
Linear Regulators
Detailed Description
The MAX8633–MAX8636 are low-power, low-quiescent
current, low-dropout linear regulators designed primarily for battery-powered applications. Pin-programmable
inputs allow easy configuration of OUT1 and OUT2 voltages without external 1% resistors. The devices can
supply up to 300mA from each output, provided they do
not exceed the maximum package power dissipation.
The MAX8633–MAX8636 regulate OUT1 and OUT2 by
using simple control loops incorporating internal 1.50V
reference, error amplifiers, p-channel pass transistors,
and internal feedback voltage-dividers. Reset circuitry
ensures controlled startup and provides undervoltage
lockout. The MAX8633–MAX8636 determine output
voltages at OUT1 and OUT2 based on the state of P1
and P2 (P for MAX8634) at power-on.
RESET (MAX8633)
The MAX8633 features an integrated reset circuit.
RESET is logic-low on power-up and goes high impedance 150ms after OUT2 reaches 87% of its nominal
regulation voltage. During power-down or undervoltage
conditions, RESET is driven low when OUT2 falls below
82.5% of its nominal regulation voltage.
Output Programming Inputs (P1, P2, P)
Output voltages for OUT1 and OUT2 are determined at
power-up by the state of P1 and P2. Programming
inputs P1 and P2 eliminate external 1% feedback resistors while providing nine preset output-voltage options
(see Table 1 for the MAX8633; see Table 3 for the
MAX8635/MAX8636).
The MAX8634 provides three preset output-voltage
options with one programming input (see Table 2). The
MAX8633–MAX8636 configure output voltages at OUT1
and OUT2 based on the state of P1 and P2 (P for
Table 1. Output-Voltage Programming
(MAX8633)
8
MAX8634) at power-on. Subsequent changes to P, or
P1 and P2 do not change the output voltages unless
the supply power is cycled, or all SHDN inputs are
simultaneously driven low to shut down the device.
Power-On Sequence
(MAX8633/MAX8636 Only)
The MAX8633/MAX8636 provide a single shutdown input
(SHDN) to disable OUT1 and OUT2. During power-on,
inrush current is limited by a built-in startup sequence. At
power-on, OUT1 is disabled until OUT2 reaches 87% of
its regulation voltage, then OUT1 is enabled.
If SHDN is connected to IN and the input voltage drops
below the undervoltage-lockout (UVLO) threshold, both
LDOs are disabled. The LDOs will not power on again
until both of the following conditions are satisfied:
1) The input voltage is raised above the UVLO threshold 2.25V (typ).
2) OUT2 is discharged below 1.2V (typ).
Internal p-Channel Pass Transistor
The MAX8633–MAX8636 feature 0.9Ω p-channel MOSFET
pass transistors; p-channel MOSFETs provide several
advantages over similar designs using pnp pass
transistors, resulting in higher efficiency and longer battery life. MOSFET pass transistors do not require base
drive current of pnps, reducing quiescent current
Table 2. Output-Voltage Programming
(MAX8634)
P
OUT1 (V)
OUT2 (V)
Open
2.85
2.85
GND
3.00
2.85
IN
2.60
2.60
Table 3. Output-Voltage Programming
(MAX8635/MAX8636)
(OUT2) (V)
P1
P2
OUT1 (V)
2.80
1.50
Open
Open
2.80
1.50
2.90
1.50
Open
GND
2.90
1.50
3.00
1.50
Open
IN
3.00
1.50
Open
3.00
1.60
GND
Open
2.60
1.80
GND
2.80
1.80
GND
GND
2.80
1.80
GND
IN
2.60
1.85
GND
IN
3.00
2.50
IN
Open
2.90
1.85
IN
Open
3.00
2.80
IN
GND
2.80
2.60
IN
GND
2.85
2.85
IN
IN
3.00
2.80
IN
IN
3.00
3.00
P1
P2
Open
Open
Open
GND
Open
IN
GND
GND
OUT1 (V)
_______________________________________________________________________________________
OUT2 (V)
Dual 300mA Pin-Programmable LDO
Linear Regulators
Current Limit
The MAX8633–MAX8636 provide independent current
limiting for OUT1 and OUT2. Output current is limited to
500mA (typ) and 400mA (min) for each regulator.
Shutdown (SHDN1, SHDN2, SHDN)
The MAX8634/MAX8635 have independent shutdown
control inputs (SHDN1 and SHDN2) and the MAX8633/
MAX8636 have one shutdown control input (SHDN) for
both outputs. Drive SHDN1 low to shut down OUT1.
Drive SHND2 low to shut down OUT2. Drive both SHDN1
and SHDN2 low to shut down the entire device, reducing
supply current to 1µA max. For the MAX8634, drive
SHDN low to shut down the entire device. Connect
SHDN1, SHDN2, or SHDN to a logic-high or IN to permanently enable the corresponding LDO(s).
Thermal-Overload Protection
Thermal-shutdown circuitry protects the MAX8633–
MAX8636 from damage due to excessive junction temperature. The shutdown circuit disables OUT1 and OUT2
when the junction temperature (TJ) exceeds +165°C.
Both regulators are reenabled when TJ falls by 15°C.
Low-Noise Operation (MAX8634/MAX8636)
An external 0.01µF bypass capacitor at BP in conjunction with an internal resistor creates a lowpass filter. The
MAX8634/MAX8636 exhibit less than 45µVRMS of output voltage noise with CBP = 0.01µF and COUT = 2.2µF.
These values are shown in the Output Noise Spectral
Density graph in the Typical Operating Characteristics
section. If output noise is not critical, omit the BP
capacitor to reduce total solution size and cost.
Applications Information
Capacitor Selection and
Regulator Stability
ture range. Output capacitors can be reduced to 1µF
for load currents less than 150mA. The MAX8633–
MAX8636 are optimized for ceramic capacitors and
require low equivalent-series resistance (ESR) to
achieve the stated specifications for low-output noise
and power-supply rejection. To ensure proper operation over the specified temperature range, dielectrics
such as X7R or X5R are recommended. If Z5U or Y5V
dielectrics are used, it may be necessary to increase the
value of the output capacitors to ensure stability at temperatures below -10°C. Tantalum capacitors are not recommended due to their higher ESR.
For loads up to 300mA, or for improved load-transient
response, 2.2µF or larger output capacitors can be used.
PSRR and Operation from
Sources Other than Batteries
The MAX8633–MAX8636 deliver low-dropout voltages
and low-quiescent currents in battery-powered systems.
When operating from sources other than batteries,
improved supply-noise rejection and transient response
can be achieved by increasing the values of the input
and output capacitors and through passive filtering techniques. Power-supply rejection is 60dB at frequencies
below 1kHz (see the Power-Supply Rejection Ratio vs.
Frequency in the Typical Operating Characteristics).
P1 and P2 (P for MAX8634)
External Termination
The pin-programmable inputs (P1 and P2 for
MAX8633/MAX8635/MAX8636, P for MAX8634) should
be connected to IN, GND, or left open. If P_ inputs are
left open, ensure the external capacitance is less than
50pF. If P_ inputs are set high or low, ensure the resistance to IN or GND is less than 1kΩ. The MAX8633–
MAX8636 configure output voltages at OUT1 and OUT2
based on the state of P1 and P2 (P for MAX8634) at
power-on. Subsequent changes to P, or P1 and P2 do
not change the output voltages unless the supply
power is cycled, or all SHDN inputs are simultaneously
driven low to shut down the device.
Load-Transient Considerations
The MAX8633–MAX8636 load-transient response
graphs (see Typical Operating Characteristics) show
two components of the output response: a DC step in
the output voltage due to the change in load current,
and the transient response. Increase the value and
decrease the ESR of the output capacitor to attenuate
transient spikes.
Use a ceramic input capacitor of at least 2.2µF and a
ceramic output capacitor of at least 2.2µF for each output to ensure stable operation over the entire tempera_______________________________________________________________________________________
9
MAX8633–MAX8636
considerably. Under heavy loads, pnp base-drive current becomes large, further reducing efficiency; pnpbased regulators also require considerable current in
dropout when the pass transistor saturates. The
MAX8633–MAX8636 do not suffer from these problems.
With both outputs active, the devices consume only
54µA of quiescent current at no load, and 60µA with
100mA load current for each output (see Typical
Operating Characteristics). A pnp-based regulator has a
high dropout voltage that is independent of the load. The
dropout voltage of a p-channel MOSFET is proportional
to load current providing for low-dropout voltage at
heavy loads and extremely low dropout at lighter loads.
MAX8633–MAX8636
Dual 300mA Pin-Programmable LDO
Linear Regulators
Input-Output Voltage (Dropout Voltage)
PC Board Layout Guidelines
A regulator’s minimum input-output voltage differential
(or dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because
the MAX8633–MAX8636 use a p-channel MOSFET
pass transistor, dropout voltage is a function of drainto-source on-resistance (RDS(ON)) multiplied by the
load current (see Typical Operating Characteristics).
Follow these guidelines for good PC board layout:
• Keep the input and output traces short and wide if
possible, especially at the ground terminals.
Calculating Maximum Output Power
The maximum output power of the MAX8633–MAX8636
is limited by the maximum power dissipation of the
package. By calculating the power dissipation of the
device as a function of the input voltage, output voltages, and output currents, the worst-case power dissipation can be obtained. The worst-case power
dissipation should not exceed the package’s maximum
power rating:
where:
PD = VIN(MAX) – VOUT1 x I OUT1 +
(
•
Use thick copper PC boards to enhance thermal
performance. Connect the exposed paddle of the
TDFN package to the ground plane or a large copper pad.
•
Place output, input, and bypass capacitors as close
as possible to the IC.
•
Ensure the noise bypass capacitor and associated
PC board traces are routed away from noise
sources to ensure low-output voltage noise.
An evaluation kit (MAX8633EVKIT) is available for a layout example to speed designs.
Selector Guide
)
(VIN(MAX) − VOUT2 ) x IOUT2
PART
OUTPUT
VOLTAGE
OPTIONS
SHDN
INPUTS
VIN(MAX) = Maximum input voltage
MAX8633
9
VOUT1 = Output voltage of OUT1
VOUT2 = Output voltage of OUT2
IOUT1 = Maximum output current of OUT1
IOUT2 = Maximum output current of OUT2
PD must be less than PDMAX, the maximum power dissipation of the package. If PD is greater than PDMAX,
consider using the 8-pin TDFN package.
P DMAX = 380mW for the 8-pin µDFN. Derate by
4.8mW/°C above +70°C.
P DMAX = 1904mW for the 8-pin TDFN. Derate by
23.8mW/°C above +70°C.
MAX8634
3
MAX8635
MAX8636
LOW
NOISE
RESET
1
—
YES
2
YES
—
9
2
—
—
9
1
YES
—
Ordering Information (continued)
PINPACKAGE
TOP
MARK
MAX8634ETA+ -40°C to +85°C
8 TDFN
3mm x 3mm
AOR
MAX8635ELA+ -40°C to +85°C
8 µDFN
2mm x 2mm
AAJ
MAX8635ETA+ -40°C to +85°C
8 TDFN
3mm x 3mm
AOS
MAX8636ELA+ -40°C to +85°C
8 µDFN
2mm x 2mm
AAK
MAX8636ETA+ -40°C to +85°C
8 TDFN
3mm x 3mm
AOT
PART
TEMP RANGE
+Denotes a lead-free/RoHS-compliant package.
10
______________________________________________________________________________________
Dual 300mA Pin-Programmable LDO
Linear Regulators
TOP VIEW
OUT1 OUT2 GND RESET
8
7
6
5
OUT1 OUT2 GND
8
MAX8633
7
6
BP
5
MAX8634
*EP
*EP
1
2
3
4
1
IN
SHDN
P2
P1
IN
2
3
4
SHDN1 SHDN2
P
2mm x 2mm μDFN
3mm x 3mm TDFN
2mm x 2mm μDFN
3mm x 3mm TDFN
OUT1 OUT2 GND SHDN2
OUT1 OUT2 GND
8
7
6
5
8
MAX8635
7
6
BP
5
MAX8636
*EP
*EP
1
2
3
4
1
2
3
4
IN
SHDN1
P2
P1
IN
SHDN
P2
P1
2mm x 2mm μDFN
3mm x 3mm TDFN
2mm x 2mm μDFN
3mm x 3mm TDFN
*EP = EXPOSED PADDLE. CONNECT EXPOSED PADDLE TO GND (TDFN ONLY).
Chip Information
PROCESS: BiCMOS
CONNECT EXPOSED PADDLE TO GND.
______________________________________________________________________________________
11
MAX8633–MAX8636
Pin Configurations
Dual 300mA Pin-Programmable LDO
Linear Regulators
MAX8633–MAX8636
Typical Operating Circuits (continued)
INPUT
2.7V TO 5.5V
IN
OUT1
CIN
2.2μF
COUT1
2.2μF
MAX8634 OUT2
COUT2
2.2μF
P
SHDN1
BP
CBP
0.01μF
SHDN2
GND
INPUT
2.7V TO 5.5V
INPUT
2.7V TO 5.5V
IN
IN
OUT1
CIN
2.2μF
COUT1
2.2μF
P1
COUT1
2.2μF
MAX8635 OUT2
MAX8636 OUT2
COUT2
2.2μF
P2
OUT1
CIN
2.2μF
COUT2
2.2μF
P1
SHDN1
P2
SHDN2
SHDN
GND
BP
CBP
0.01μF
GND
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
12
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
8 TDFN
T833-2
21-0137
8 µDFN
L822-1
21-0164
______________________________________________________________________________________
Dual 300mA Pin-Programmable LDO
Linear Regulators
PAGES
CHANGED
REVISION
NUMBER
REVISION
DATE
0
4/06
Initial release
—
1
9/08
Added LDO SHDN restart conditions
8
DESCRIPTION
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 ____________________ 13
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
MAX8633–MAX8636
Revision History
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