MAX8734 Maxim Integrated Products, MAX8734 Datasheet - Page 13

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

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MAX8732
MAX8733
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PIN
Supply Controllers for Notebook Computers
MAX8734
High-Efficiency, Quad-Output, Main Power-
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NAME
LDO5
OUT5
OUT3
LDO3
BST5
BST3
GND
TON
DH5
DH3
CS5
V
LX5
DL5
DL3
LX3
V+
CC
5V SMPS Current-Sense Input. Connect CS5 to a current-sensing resistor from the source of
the synchronous rectifier to GND. The voltage at ILIM5 determines the current-limit threshold
(see the Current-Limit Circuit section).
Frequency Select Input. Connect to V
400kHz/500kHz operation (5V/3.3V SMPS switching frequencies, respectively).
Boost Flying Capacitor Connection for 5V SMPS. Connect to an external capacitor and diode
according to the typical application circuits (Figure 1 and Figure 2). See the MOSFET Gate
Drivers (DH_, DL_) section.
Inductor Connection for 5V SMPS. LX5 is the internal lower supply rail for the DH5 high-side
gate driver. LX5 is the current-sense input for the 5V SMPS (MAX8734 only).
High-Side MOSFET Floating Gate-Driver Output for 5V SMPS. DH5 swings from LX5 to BST5.
Analog Supply Voltage Input for PWM Core. Connect V
series 50 resistor. Bypass to GND with a 1µF ceramic capacitor.
5V Linear-Regulator Output. LDO5 is the gate-driver supply for the external MOSFETs. LDO5
can provide a total of 100mA, including MOSFET gate-drive requirements and external loads.
The internal load depends on the choice of MOSFET and switching frequency (see the
Reference and Linear Regulators (REF, LDO5, and LDO3) section). If OUT5 is greater than the
LDO5 bootstrap switch threshold, the LDO5 regulator shuts down and the LDO5 pin connects
to OUT5 through a 1.4 switch. Bypass LDO5 with a minimum of 4.7µF. Use an additional 1µF
per 5mA of load.
5V SMPS Synchronous Rectifier Gate-Drive Output. DL5 swings between GND and LDO5.
Power-Supply Input. V+ powers the LDO5/LDO3 linear regulators and is also used for the
Quick-PWM on-time one-shot circuits. Connect V+ to the battery input through a 4 resistor
and bypass with a 4.7µF capacitor.
5V SMPS Output Voltage-Sense Input. Connect to the 5V SMPS output. OUT5 is an input to the
Quick-PWM on-time one-shot circuit. It also serves as the 5V feedback input in fixed-voltage
mode. If OUT5 is greater than the LDO5 bootstrap-switch threshold, the LDO5 linear regulator
shuts down and LDO5 connects to OUT5 through a 1.4 switch.
3.3V SMPS Output Voltage-Sense Input. Connect to the 3.3V SMPS output. OUT3 is an input to
the Quick-PWM on-time one-shot circuit. It also serves as the 3V feedback input in fixed-
voltage mode. If OUT3 is greater than the LDO3 bootstrap-switch threshold, the LDO3 linear
regulator shuts down and LDO3 connects to OUT3 through a 1.5 switch.
Analog and Power Ground
3.3V SMPS Synchronous-Rectifier Gate-Drive Output. DL3 swings between GND and LDO5.
3.3V Linear-Regulator Output. LDO3 powers up after REF is in regulation. LDO3 can provide a
total of 100mA to external loads. If OUT3 is greater than the LDO3 bootstrap-switch threshold,
the LDO3 regulator shuts down and the LDO3 pin connects to OUT3 through a 1.5 switch.
Bypass LDO3 with a minimum of 4.7µF. Use an additional 1µF per 5mA of load.
High-Side MOSFET Floating Gate-Driver Output for 3.3V SMPS. DH3 swings from LX3 to BST3.
Inductor Connection for 3.3V SMPS. LX3 is the current-sense input for the 3.3V SMPS
(MAX8734 only).
Boost Flying Capacitor Connection for 3.3V SMPS. Connect to an external capacitor and diode
according to the typical application circuits (Figure 1 and Figure 2). See the MOSFET Gate
Drivers (DH_, DL_) section.
CC
for 200kHz/300kHz operation and to GND for
FUNCTION
Pin Description (continued)
CC
to the system supply voltage with a
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