RT9403A/B/C
I
2
C Programmable High Precision Reference Voltage Generator
General Description
The RT9403A/B/C is a high precision reference voltage
generating console consisting of three I
2
C programmable
DACs. Each DAC output voltage is controlled by 7 digital
bits that are programmed by the I
2
C interface. The
RT9403A/B/C features adjustable output slew rate, low
switching glitch and adequate driving capability. The
RT9403A/B/C is available in SOT-23-8 package.
Features
5V Supply Voltage
Provide 3 Precise Voltage DACs
I
2
C Programmable 128-Steps Output Voltage
Output Range and Resolution
DAC1 & DAC2 : 0.6V to 2.1875V, 12.5mV/Step
DAC3 : 1.2V to 3.375V, 12.5mV (or 25mV)/Step for
Different Segments
High Output Accuracy Up to 1% (V
OUT
≥
1V)
Low External Component Count
Small Footprint SOT-23-8 Package
RoHS Compliant and Halogen Free
Ordering Information
RT9403A/B/C
Package Type
V8 : SOT-23-8
Lead Plating System
G : Green (Halogen Free and Pb Free)
Address Bit [A1,A0]
A : [0,1]
B : [1,0]
C : [1,1]
Note :
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.
Applications
Power Supply Adjustment for Motherboard and Graphic
Card
Low Voltage, High Accuracy Reference Voltage Circuit
Pin Configurations
(TOP VIEW)
VOUT3
VOUT2
6
3
8
7
Marking Information
VDD
2
GND
01= : Product Code
01=DNN
DNN : Date Code
SOT-23-8
RT9403BGV8
02= : Product Code
02=DNN
DNN : Date Code
RT9403CGV8
04= : Product Code
04=DNN
DNN : Date Code
DS9403A/B/C-00 May 2011
SDA
SCL
RT9403AGV8
VOUT1
5
4
S3/EN
www.richtek.com
1
RT9403A/B/C
Typical Application Circuit
V
IN1
REFIN
3.3V/5V
5V
RT9403A/B/C
C
OUT1
DC/DC
Converter
V1
1 VDD
C
IN
VOUT1
5
REFIN
C
OUT2
V
IN2
VOUT2 6
Data Bus Line
Clock Bus Line
S3/EN
4 SDA
3
SCL
8 S3/EN
VOUT3 7
GND
2
DC/DC
Converter
V
IN3
V2
REFIN
C
OUT3
DC/DC
Converter
V3
Functional Pin Description
Pin No.
1
2
3
4
5
6
7
8
Pin Name
VDD
GND
SCL
SDA
VOUT1
VOUT2
VOUT3
S3/EN
Pin Function
Power Supply Input. Default connected to 5V.
Ground.
Serial Clock Input. This pin receives I C serial bus clock signal.
Serial Data Input. This pin is input or output of I C serial bus data signal.
I C Programmed VTT Output Voltage. Default = 1.1V
I C Programmed PCH_CORE Output Voltage. Default = 1.05V
I C Programmed DDR Output Voltage. Default = 1.5V
ACPI S3 State/Enable. Active low for entering ACPI S3 State(suspend to RAM),
VOUT1/VOUT2 are internally pulled down to zero, only VOUT3 is active.
2
2
2
2
2
Function Block Diagram
VDD
POR
DAC1
7 bit
VOUT1
S3/EN
I C
Interface
2
SCL
SDA
Control and
Monitoring Unit
DAC2
7 bit
VOUT2
GND
DAC3
7 bit
VOUT3
www.richtek.com
2
DS9403A/B/C-00 May 2011
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