MAX8734 Maxim Integrated Products, MAX8734 Datasheet - Page 12

• Manufacturer Part Number: MAX8734
• Description: (MAX8732 - MAX8734) Main Power-Supply Controllers
• Manufacturer: Maxim Integrated Products

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High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
12
MAX8732
MAX8733
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3
4
5
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9
PIN
MAX8734
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3
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5
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7
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9
PGOOD
NAME
SHDN
ILIM3
ILIM5
SKIP
N.C.
ON3
ON5
PRO
CS3
FB3
REF
FB5
3.3V SMPS Current-Sense Input. Connect CS3 to a current-sensing resistor from the source of
the synchronous rectifier to GND. The voltage at ILIM3 determines the current-limit threshold
(see the Current-Limit (ILIM) Circuit section).
No Connection. Not internally connected.
Power-Good Output. PGOOD is an open-drain output that is pulled low if either output is
disabled or is more than 10% below its nominal value.
3.3V SMPS Enable Input. The 3.3V SMPS is enabled if ON3 is greater than the SMPS on level
and disabled if ON3 is less than the SMPS off level. If ON3 is connected to REF, the 3.3V
SMPS starts after the 5V SMPS reaches regulation (delay start). Drive ON3 below the clear
fault level to reset the fault latches.
5V SMPS Enable Input. The 5V SMPS is enabled if ON5 is greater than the SMPS on level and
disabled if ON5 is less than the SMPS off level. If ON5 is connected to REF, the 5V SMPS
starts after the 3.3V SMPS reaches regulation (delay start). Drive ON5 below the clear fault
level to reset the fault latches.
3.3V SMPS Current-Limit Adjustment. The GND-LX current-limit threshold defaults to 100mV if
ILIM3 is connected to V
seen at ILIM3 over a 0.5V to 3V range. The logic threshold for switchover to the 100mV default
value is approximately V
Shutdown Control Input. The device enters its 6µA supply current shutdown mode if
V
greater than the SHDN input rising-edge trip level. Connect SHDN to V+ for automatic startup.
SHDN can be connected to V+ through a resistive voltage-divider to implement a
programmable undervoltage lockout.
3.3V SMPS Feedback Input. Connect FB3 to GND for fixed 3.3V operation. Connect FB3 to a
resistive voltage-divider from OUT3 to GND to adjust the output from 2V to 5.5V.
2V Reference Output. Bypass to GND with a 0.22µF (min) capacitor. REF can source up to
100µA for external loads. Loading REF degrades FB_ and output accuracy according to the
REF load-regulation error.
5V SMPS Feedback Input. Connect FB5 to GND for fixed 5V operation. Connect FB5 to a
resistive voltage-divider from OUT5 to GND to adjust the output from 2V to 5.5V.
Overvoltage and Undervoltage Fault Protection Enable/Disable. Connect PRO to V
disable undervoltage, overvoltage protection, and discharge mode (DL = low in shutdown).
Connect PRO to GND to enable undervoltage and overvoltage protection (see the Fault
Protection section), and output discharge mode.
5V SMPS Current-Limit Adjustment. The GND-LX current-limit threshold defaults to 100mV if
ILIM5 is connected to V
seen at ILIM5 over a 0.5V to 3V range. The logic threshold for switchover to the 100mV default
value is approximately V
Low-Noise Mode Control. Connect SKIP to GND for normal Idle-Mode (pulse-skipping)
operation or to V
lt
SHDN
is less than the SHDN input falling-edge trip level and does not restart until V
i
d (
CC
for PWM mode (fixed frequency). Connect to REF or leave floating for
l
CC
CC
CC
CC
ki
. In adjustable mode, the current-limit threshold is 1/10th the voltage
. In adjustable mode, the current-limit threshold is 1/10th the voltage
- 1V. Connect ILIM3 to REF for a fixed 200mV threshold.
- 1V. Connect ILIM5 to REF for a fixed 200mV threshold.
i
25kH
FUNCTION
i )
Pin Description
CC
SHDN
to
is