Preliminary
RT9907
3 Channel DC/DC Converters IC with High-Efficiency Step-Up
and Step-Down
General Description
The RT9907 is a three channel power-supply solution for
digital still cameras and other battery-powered devices. It
integrates an asynchronous step-up and two synchronous
step-down DC-DC converters. The RT9907 is targeted for
applications that use two AA cells or a single lithium-ion
battery.
The three DC-DC converters (CH1, CH2, CH3) accept input
voltage from 1.5V to 5.5V. Each DC-DC converter has
better transient response and excellent stability by
providing current-mode control and external compensation
network. With built-in Internal MOSFET and up to 1.4MHz
operating frequency, the RT9907 allows minimum BOM
cost and PCB area.
The step-down DC-DC converters (CH2, CH3) can regulate
output voltage as low as 0.8V. Three operational modes
are available: PWM, PSM, Low-Dropout modes. At PWM
mode, Internal synchronous rectifier with low R
DS(ON)
dramatically reduces conduction loss and achieve 94%
efficiency. It enters Low-Dropout mode when normal PWM
cannot provide regulated output voltage by continuously
turning on the upper P-MOSFET. No external Schottky
diode is required in practical application.
Each DC-DC converter has independent enable input and
soft-start function allowing versatile power sequence
combination. Complete protection functions are
implemented such as short circuit, over-voltage protection.
The RT9907 is available in small VQFN-24L 4x4 package.
GND
EN3
FB3
EN2
Features
1.5V to 5.5V Battery Input Voltage Range
Main step-up DC-DC Converter
1.5V to 5.5V Adjustable Output Voltage
Up to 90% Efficiency
2.6A, 0.3Ω Internal Power Switch
Ω
Two Step-Down DC-DC Converters
0.8V to 5.5V Adjustable Output Voltage
94% Efficiency
100% Duty Cycle
Up to 1.4MHz Switching Frequency
1μA Supply Current in Shutdown Mode
μ
Programmable Soft Start Function
Independent Enable Pin (CH1, CH2, CH3)
External Compensation Network (CH1, CH2, CH3)
Short Circuit Protection (CH1, CH2, CH3)
Over Voltage Protection (CH2)
24-Lead VQFN Package
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Digital Still Camera
PDAs
Portable Device
Pin Configurations
(TOP VIEW)
COMP2
19
18
17
16
Ordering Information
RT9907
Package Type
QV : VQFN-24L 4x4 (V-Type)
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
COMP3
VDD3
LX3
PGND3
SS
RT
1
2
3
4
5
6
24
23
22
21
FB2
20
EN1
ENM
VDD2
LX2
PGND2
LX1
GND
15
14
25
13
COMP1
FB1
VDDM
Richtek Pb-free and Green 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.
100% matte tin (Sn) plating.
DS9907-07 August 2007
VQFN-24L 4x4
PGND1
VDD1
GND
Note :
7
8
9
10
11
12
www.richtek.com
1
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
