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 pulsewidth
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 outputs.
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 internal
soft-stop output discharge that prevents negative voltages
on shutdown. Additionally, the outputs are high
impedance when VCC falls below its UVLO set point while
the outputs are enabled.

Maxim’s proprietary Quick-PWM™ quick-response, constant
on-time PWM control scheme operates without
sense resistors and provides 100ns response to load transients
while maintaining a relatively constant switching frequency.
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 features
a 400kHz/5V and 500kHz/3.3V SMPS for “thin and
light” applications. The MAX8734A provides a pinselectable
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