19-3711; Rev 0; 5/05
High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
General Description
The MAX8732A/MAX8733A/MAX8734A dual step-down,
switch-mode power-supply (SMPS) controllers generate
logic-supply voltages in battery-powered systems. The
MAX8732A/MAX8733A/MAX8734A include two pulse-
width modulation (PWM) controllers, adjustable from 2V to
5.5V or fixed at 5V and 3.3V. These devices feature two
linear regulators providing 5V and 3.3V always-on out-
puts. Each linear regulator provides up to 100mA output
current with automatic linear-regulator bootstrapping to
the main SMPS outputs. The MAX8732A/MAX8733A/
MAX8734A include on-board power-up sequencing, a
power-good (PGOOD) output, digital soft-start, and inter-
nal soft-stop output discharge that prevents negative volt-
ages on shutdown. Additionally, the outputs are high
impedance when V
CC
falls below its UVLO set point while
the outputs are enabled.
Maxim’s proprietary Quick-PWM™ quick-response, con-
stant on-time PWM control scheme operates without
sense resistors and provides 100ns response to load tran-
sients while maintaining a relatively constant switching fre-
quency. The unique ultrasonic pulse-skipping mode
maintains the switching frequency above 25kHz, which
eliminates noise in audio applications. Other features
include pulse skipping, which maximizes efficiency in
light-load applications, and fixed-frequency PWM mode,
which reduces RF interference in sensitive applications.
The MAX8732A features a 200kHz/5V and 300kHz/3.3V
SMPS for highest efficiency, while the MAX8733A fea-
tures a 400kHz/5V and 500kHz/3.3V SMPS for “thin and
light” applications. The MAX8734A provides a pin-
selectable switching frequency, allowing either 200kHz/
300kHz or 400kHz/500kHz operation of the 5V/3.3V
SMPSs, respectively. The MAX8732A/MAX8733A/
MAX8734A are available in 28-pin QSOP packages and
operate over the extended temperature range
(-40°C to +85°C).
The MAX8732A/MAX8733A/MAX8734A are pin-for-pin
upgrades to the MAX1777/MAX1977/MAX1999.
The MAX1999 evaluation kit (EV kit) can be used to
evaluate the MAX8732A/MAX8733A/MAX8734A.
Features
♦
No Current-Sense Resistor Needed (MAX8734A)
♦
Accurate Current Sense with Current-Sense
Resistor (MAX8732A/MAX8733A)
♦
1.5% Output Voltage Accuracy
♦
3.3V and 5V 100mA Bootstrapped Linear
Regulators
♦
Internal Soft-Start and Soft-Stop Output
Discharge
♦
Quick-PWM with 100ns Load Step Response
♦
3.3V and 5V Fixed or Adjustable Outputs
(Dual Mode™)
♦
4.5V to 24V Input Voltage Range
♦
Enhanced Ultrasonic Pulse-Skipping Mode
(25kHz min)
♦
Power-Good (PGOOD) Signal
♦
Overvoltage Protection Enable/Disable
MAX8732A/MAX8733A/MAX8734A
Ordering Information
PART
PIN-
TEMP RANGE
PACKAGE
5V/3.3V
SWITCHING
FREQUENCY
(kHz)
200/300
200/300
400/500
400/500
MAX8732AEEI+
-40°C to +85°C 28 QSOP
MAX8732AEEI
MAX8733AEEI
-40°C to +85°C 28 QSOP
-40°C to +85°C 28 QSOP
MAX8733AEEI+
-40°C to +85°C 28 QSOP
Ordering Information continued at end of data sheet.
+Denotes
lead-free package.
Pin Configurations
TOP VIEW
N.C. 1
PGOOD 2
ON3 3
ON5 4
ILIM3 5
SHDN 6
FB3 7
REF 8
FB5 9
PRO 10
ILIM5 11
SKIP 12
TON 13
28 BST3
27 LX3
26 DH3
25 LDO3
24 DL3
MAX8734A
23 GND
22 OUT3
21 OUT5
20 V+
19 DL5
18 LDO5
17 V
CC
16 DH5
15 LX5
Applications
Notebook and Subnotebook Computers
PDAs and Mobile Communication Devices
3- and 4-Cell Li+ Battery-Powered Devices
Quick-PWM and Dual Mode are trademarks of Maxim
Integrated Products, Inc.
BST5 14
QSOP
Pin Configurations continued at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
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.
High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
MAX8732A/MAX8733A/MAX8734A
ABSOLUTE MAXIMUM RATINGS
V+,
SHDN
to GND ..................................................-0.3V to +25V
BST_ to GND ..........................................................-0.3V to +30V
LX_ to BST_ ..............................................................-6V to +0.3V
CS_ to GND (MAX8732A/MAX8733A only) .................-2V to +6V
V
CC
, LDO5, LDO3, OUT3, OUT5, ON3, ON5, REF,
FB3, FB5,
SKIP, PRO,
PGOOD to GND ...............-0.3V to +6V
DH3 to LX3 ..............................................-0.3V to (V
BST3
+ 0.3V)
DH5 to LX5 ..............................................-0.3V to (V
BST5
+ 0.3V)
ILIM3, ILIM5 to GND...................................-0.3V to (V
CC
+ 0.3V)
DL3, DL5 to GND....................................-0.3V to (V
LDO5
+ 0.3V)
TON to GND (MAX8734A only) ................................-0.3V to +6V
LDO3, LDO5, REF Short Circuit to GND ....................Momentary
LDO3 Current (internal regulator) Continuous................+100mA
LDO3 Current (switched over to OUT3) Continuous ......+200mA
LDO5 Current (internal regulator) Continuous................+100mA
LDO5 Current (switched over to OUT5) Continuous ......+200mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin QSOP (derate 10.8mW/°C above +70°C).........860mW
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
(Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = V
CC
, V
SHDN
= 5V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
MAIN SMPS CONTROLLERS
V+ Input Voltage Range
3.3V Output Voltage in
Fixed Mode
LDO5 in regulation
V+ = LDO5, V
OUT5
< 4.43V
V+ = 6V to 24V, FB3 = GND, V
SKIP
= 5V
V+ = 6V to 24V, FB5 = GND, V
SKIP
= 5V,
MAX8732A/MAX8734A (TON = V
CC
)
V+ = 7V to 24V, FB5 = GND, V
SKIP
= 5V,
MAX8733A/MAX8734A (TON = GND)
Output Voltage in
Adjustable Mode
Output Voltage Adjust Range
FB3, FB5 Adjustable-Mode
Threshold Voltage
DC Load Regulation
Line Regulation
Current-Limit Threshold
(Positive, Default)
Current-Limit Threshold
(Positive, Adjustable)
Zero-Current Threshold
Current-Limit Threshold
(Negative, Default)
Soft-Start Ramp Time
V+ = 6V to 24V, either SMPS
Either SMPS
Dual-Mode comparator
Either SMPS, V
SKIP
= 5V, 0 to 5A
Either SMPS,
SKIP
= GND, 0 to 5A
Either SMPS, V
SKIP
= 2V, 0 to 5A
Either SMPS, 6V < V+ < 24V
ILIM_ = V
CC
, GND - CS_ (MAX8732A/MAX8733A),
GND - LX_ (MAX8734A)
GND - CS_
(MAX8732A/MAX8733A),
GND - LX_ (MAX8734A)
V
ILIM_
= 0.5V
V
ILIM_
= 1V
V
ILIM_
= 2V
93
40
93
185
1.975
2.0
0.1
-0.1
-1.5
-1.7
0.005
100
50
100
200
3
-120
1.7
107
60
107
215
mV
mV
ms
mV
%/V
mV
%
2.00
2.025
5.5
0.2
V
V
V
6
4.5
3.285
3.330
24
5.5
3.375
V
V
CONDITIONS
MIN
TYP
MAX
UNITS
5V Output Voltage in Fixed Mode
4.975
5.050
5.125
V
SKIP
= GND, ILIM_ = V
CC
, GND - CS_
(MAX8732A/MAX8733A), GND - LX_ (MAX8734A)
SKIP
= ILIM_ = V
CC
, GND - CS_
(MAX8732A/MAX8733A), GND - LX_ (MAX8734A)
Zero to full limit
2
_______________________________________________________________________________________
High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = V
CC
, V
SHDN
= 5V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
CONDITIONS
MAX8732A or MAX8734A
(V
TON
= 5V),
SKIP
= V
CC
Operating Frequency
MAX8733A or MAX8734A
(V
TON
= 0),
SKIP
= V
CC
SKIP = REF
MAX8732A or MAX8734A
(V
TON
= 5V)
MAX8733A or MAX8734A
(V
TON
= 0)
Minimum Off-Time
MAX8732A or MAX8734A
(V
TON
= 5V)
MAX8733A or MAX8734A
(V
TON
= 0)
V
OUT5
= 5.05V
V
OUT3
= 3.33V
V
OUT5
= 5.05V
V
OUT3
= 3.33V
4.90
V
OUT5
= 5.05V
V
OUT3
= 3.33V
V
OUT5
= 5.05V
V
OUT3
= 3.33V
5V SMPS
3.3V SMPS
5V SMPS
3.3V SMPS
25
1.895
0.833
0.895
0.475
250
MIN
TYP
200
300
400
500
36
2.105
0.925
1.052
0.555
300
94
91
88
85
5.00
190
3.7
4.43
4.0
4.56
1.4
3.28
3.35
180
2.80
2.91
1.5
1.980
10
25
150
6
3
50
250
15
4.5
2.000
3.02
3.5
2.020
10
4.3
4.69
3.2
3.42
5.10
V
mA
V
V
Ω
V
mA
V
Ω
V
mV
µA
µA
µA
µA
mW
%
2.315
1.017
1.209
0.635
350
ns
µs
kHz
MAX
UNITS
MAX8732A/MAX8733A/MAX8734A
On-Time Pulse Width
Maximum Duty Cycle
INTERNAL REGULATOR AND REFERENCE
LDO5 Output Voltage
ON3 = ON5 = GND, 6V < V+ < 24V, 0 < I
LDO5
< 100mA
LDO5 Short-Circuit Current
LDO5 Undervoltage-Lockout
Fault Threshold
LDO5 Bootstrap Switch Threshold
LDO5 Bootstrap
Switch Resistance
LDO3 Output Voltage
LDO3 Short-Circuit Current
LDO3 Bootstrap Switch Threshold
LDO3 Bootstrap Switch
Resistance
REF Output Voltage
REF Load Regulation
REF Sink Current
V+ Operating Supply Current
V+ Standby Supply Current
V+ Shutdown Supply Current
Quiescent Power Consumption
FAULT DETECTION
Overvoltage Trip Threshold
FB3 or FB5 with respect to nominal regulation point
LDO5 = GND
Falling edge of LDO5, hysteresis = 1%
Falling edge of OUT5, rising edge at OUT5 regulation
point
LDO5 to OUT5, V
OUT5
= 5V
ON3 = ON5 = GND, 6V < V+ < 24V, 0 < I
LDO3
< 100mA
LDO3 = GND
Falling edge of OUT3, rising edge at OUT3 regulation
point
LDO3 to OUT3, V
OUT3
= 3.2V
No external load
0 < I
LOAD
< 50µA
REF in regulation
LDO5 switched over to OUT5, 5V SMPS
V+ = 6V to 24V, both SMPSs off, includes I
SHDN
V+ = 4.5V to 24V
Both SMPSs on, FB3 = FB5 =
SKIP
= GND, V
OUT3
=
3.5V, V
OUT5
= 5.3V
+8
+11
+14
%
_______________________________________________________________________________________
3
High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
MAX8732A/MAX8733A/MAX8734A
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = V
CC
, V
SHDN
= 5V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Overvoltage Fault
Propagation Delay
PGOOD Threshold
PGOOD Propagation Delay
PGOOD Output Low Voltage
PGOOD Leakage Current
Thermal-Shutdown Threshold
Output Undervoltage
Shutdown Threshold
Output Undervoltage
Shutdown Blanking Time
INPUTS AND OUTPUTS
Feedback Input Leakage Current
PRO
Input Voltage
V
FB3
= V
FB5
= 2.2V
Low level
High level
Low level
SKIP
Input Voltage
Float level
High level
TON Input Voltage
Low level
High level
Clear fault level/SMPS off level
ON3, ON5 Input Voltage
Delay start level
SMPS on level
V
PRO
or V
TON
= 0 or 5V
V
ON_
= 0 or 5V
Input Leakage Current
V
SKIP
= 0 or 5V
V
SHDN
= 0 or 24V
V
CS_
= 0 or 5V
V
ILIM3
, V
ILIM5
= 0 or 2V
SHDN
Input Trip Level
DH_ Gate-Driver
Sink/Source Current
DL_ Gate-Driver Source Current
DL_ Gate-Driver Sink Current
DH_ Gate-Driver On-Resistance
DL_ Gate-Driver On-Resistance
Rising edge
Falling edge
DH3, DH5 forced to 2V
DL3 (source), DL5 (source), forced to 2V
DL3 (sink), DL5 (sink), forced to 2V
BST - LX_ forced to 5V
DL_, high state (pullup)
DL_, low state (pulldown)
1.7
2.4
-1
-2
-1
-1
-2
-0.2
1.2
0.96
1.6
1.00
2
1.7
3.3
1.5
2.2
0.6
4.0
5.0
1.5
+1
+2
+1
+1
+2
+0.2
2.0
1.04
V
A
A
A
Ω
Ω
µA
2.4
0.8
2.3
V
1.7
2.4
0.8
V
1.5
0.8
2.3
V
-200
+40
+200
0.6
nA
V
FB3 or FB5 with respect to nominal output voltage
From ON_ signal
65
10
CONDITIONS
FB3 or FB5 delay with 50mV overdrive
FB3 or FB5 with respect to nominal output, falling edge,
typical hysteresis = 1%
Falling edge, 50mV overdrive
I
SINK
= 4mA
High state, forced to 5.5V
+160
70
22
75
35
-12
MIN
TYP
10
-9.5
10
0.3
1
-7
MAX
UNITS
µs
%
µs
V
µA
o
C
%
ms
4
_______________________________________________________________________________________
High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = V
CC
, V
SHDN
= 5V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
OUT3, OUT5 Discharge-Mode
On-Resistance
OUT3, OUT5 Discharge-Mode
Synchronous Rectifier
Turn-On Level
0.2
CONDITIONS
MIN
TYP
12
MAX
40
UNITS
Ω
MAX8732A/MAX8733A/MAX8734A
0.3
0.4
V
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = V
CC
, V
SHDN
= 5V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
MAIN SMPS CONTROLLERS
V+ Input Voltage Range
3.3V Output Voltage in
Fixed Mode
LDO5 in regulation
V+ = LDO5, V
OUT5
< 4.41V
V+ = 6V to 24V, FB3 = GND, V
SKIP
= 5V
V+ = 6V to 24V, FB5 = GND, V
SKIP
= 5V,
MAX8732A/MAX8734A (TON = V
CC
)
V+ = 7V to 24V, FB5 = GND, V
SKIP
= 5V,
MAX8733A/MAX8734A (TON = GND)
Output Voltage in
Adjustable Mode
Output Voltage Adjust Range
FB3, FB5 Adjustable-Mode
Threshold Voltage
Current-Limit Threshold
(Positive, Default)
Current-Limit Threshold
(Positive, Adjustable)
V+ = 6V to 24V, either SMPS
Either SMPS
Dual-Mode comparator
ILIM_ = V
CC
, GND - CS_ (MAX8732A/MAX8733A),
GND - LX_ (MAX8734A)
GND - CS_
(MAX8732A/MAX8733A),
GND - LX_ (MAX8734A)
MAX8732A or MAX8734A
(V
TON
= 5V)
MAX8733A or MAX8734A
(V
TON
= 0)
Minimum Off-Time
INTERNAL REGULATOR AND REFERENCE
LDO5 Output Voltage
LDO5 Undervoltage-Lockout
Fault Threshold
ON3 = ON5 = GND, 6V < V+ < 24V, 0 < I
LDO5
< 100mA
Falling edge of LDO5, hysteresis = 1%
4.90
3.7
5.10
4.3
V
V
V
ILIM_
= 0.5V
V
ILIM_
= 1V
V
ILIM_
= 2V
V
OUT5
= 5.05V
V
OUT3
= 3.33V
V
OUT5
= 5.05V
V
OUT3
= 3.33V
1.97
2.0
0.1
90
40
90
180
1.895
0.833
0.895
0.475
200
2.03
5.5
0.2
110
60
110
220
2.315
1.017
1.209
0.635
400
ns
µs
mV
V
V
V
mV
6
4.5
3.27
24
5.5
3.39
V
V
CONDITIONS
MIN
TYP
MAX
UNITS
5V Output Voltage in Fixed Mode
4.95
5.15
V
On-Time Pulse Width
_______________________________________________________________________________________
5
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