RT8240A/B/C
High Efficiency Single Synchronous Buck PWM Controller
General Description
Features
The RT8240A/B/C PWM controller provides high efficiency, z Built-in 0.5% Reference Voltage
excellent transient response, and high DC output accuracy z 1 Bit Programmable Output Voltage Between 1V
needed for stepping down high voltage batteries to
and 1.05V with Integrated Transition Support
generate low voltage CPU core, I/O, and chipset RAM z Output Voltage Range from 1V to 3.6V
supplies in notebook computers.
z Quick Load-Step Response within 100ns
The RT8240A/B/C supports on chip voltage programming
function between 1V and 1.05V by controlling G0 digital
inputs.
The constant on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides 100ns
“instant-on” response to load transients while maintaining
a relatively constant switching frequency.
The RT8240A/B/C achieves high efficiency at a reduced
cost by eliminating the current sense resistor found in
traditional current mode PWMs. Efficiency is further
enhanced by its ability to drive very large synchronous
rectifier MOSFETs and enter diode emulation mode at
light load condition. The buck conversion allows this device
to directly step down high voltage batteries at the highest
possible efficiency. The RT8240A/B/C is intended for CPU
core, chipset, DRAM, or other low voltage supplies as
z Support Pure MLCC Output Capacitor
z 4700ppm/°C Programmable Current Limit by Low
Side RDS(ON) Sensing
z 4.5V to 26V Battery Input Range
z Internal Ramp Current Limit Soft-Start Control
z Drives Large Synchronous Rectifier FETs
z Integrated Boost Switch
z Over/Under Voltage Protection
z Thermal Shutdown
z Power Good Indicator
z RoHS Compliant and Halogen Free
Applications
z Notebook Computers
z CPU/GPU Core Supply
z Chipset/RAM Supply
z Generic DC/DC Power Regulator
low as 1V. The RT8240A/B/C is available in a WQFN -12L
2x2 package.
Ordering Information
Pin Configurations
(TOP VIEW)
RT8240A/B/C
Package Type
QW : WQFN-12L 2x2 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Z : ECO (Ecological Element with
Halogen Free and Pb free)
12 11 10
LGATE 1
PHASE 2
UGATE 3
GND
13
9 PGOOD
8 EN
7 RGND
4 56
Note :
Switching Frequency Operation
A : 300kHz
B : 400kHz
C : 500kHz
WQFN-12L 2x2
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
DS8240A/B/C-02 April 2011
www.richtek.com
1
