General Description
The RT5759A is a high-performance, synchronous stepdown
DC-DC converter that can deliver up to 9A output
current from a 3V to 6.5V input supply. The output voltage
can be programmable from 0.6V to 1.725V with I2C
controlled 7-Bit VID.
The device integrates low RDS(ON) power MOSFETs,
accurate 0.6V reference and an integrated diode of
bootstrap circuit to offer a very compact solution.
The RT5759A adopts Advanced Constant On-Time
(ACOT® ) control architecture that provides ultrafast
transient response and further reduces the externalcomponent
count. In steady states, the ACOT® operates
in nearly constant switching frequency over line, load and
output voltage ranges and makes the EMI filter design
easier. The RT5759A offers automatic PSM that maintains
high efficiency during light load operation. The RT5759A
can also operate in Forced-CCM through I2C setting that
helps meet tight voltage regulation accuracy requirements.
The device offers a variety of functions for more design
flexibility. The switching frequency, current limit level and
over-temperature threshold are selectable via I2C.
Independent enable control input pin and power good
indicator are also provided for easy sequence control.
Besides, the designer can also command the device to
be enabled or shutdown via the I2C interface.
The device offers independent enable control input pin and
power good indicator for easy sequence control. To control
the inrush current during the startup, the device provides
a programmable soft-start up by an external capacitor
connected to the SS pin. Full protection features are also
integrated in the device, including the cycle-by-cycle
current limit control, UVP, input UVLO and OTP.
The RT5759A is available in a thermally enhanced UQFN-
13L 3x3 (FC) package.

Features
 Dramatically Fast Transient Response
 Steady 1MHz ±20% Switching Frequency
 Advanced COT Control Loop
 Optimized for Ceramic Output Capacitors
 3V to 6.5V Input Voltage Range
 Integrated 12mΩ/8mΩ MOSFETs
 Internal Start-Up into Pre-Biased Outputs
 Power Good Indicator
 Enable Control
 Overcurrent and Over-Temperature Protections
 Undervoltage Protection with Hiccup Mode
 VID Control Range Via I2C Compatible Interface
0.6V to 1.725V step = 12.5mV

Applications
 Mobile Phones and Handheld Devices
 STB, Cable Modem, and xDSL Platform
 WLAN ASIC Power / Storage (SSD and HDD)
 General Purpose for POL LV Buck Converter
 TV