RT9403 - Richtek

RT9403
I2C Programmable High Precision Reference Voltage
Generator
General Description
Features
The RT9403 is a high precision reference voltage generating
console consisting of three I2C programmable DACs. Each
z
5V Supply Voltage
z
DAC output voltage is controlled by 7 digital bits that are
programmed by the I2C interface. The RT9403 features
adjustable output slew rate, low switching glitch and
adequate driving capability. The RT9403 is available in
SOT-23-8 package.
z
Provide 3 Precise Voltage DACs
I2C 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% (VOUT ≥ 1V)
Low External Component Count
Small Footprint SOT-23-8 Package
RoHS Compliant and Halogen Free
z
z
Ordering Information
z
RT9403
z
Package Type
V8 : SOT-23-8
z
Lead Plating System
G : Green (Halogen Free and Pb Free)
Applications
z
Note :
Richtek products are :
z
RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
Pin Configurations
Suitable for use in SnPb or Pb-free soldering processes.
VOUT2
VOUT1
8
7
6
5
2
3
4
SDA
VDD
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
SCL
Marking Information
VOUT3
(TOP VIEW)
GND
`
S3/EN
`
Power Supply Adjustment for Motherboard and Graphic
Card
Low Voltage, High Accuracy Reference Voltage Circuit
SOT-23-8
Typical Application Circuit
VIN1
REFIN
3.3V/5V
5V
Data Bus Line
Clock Bus Line
S3/EN
COUT1
RT9403
1 VDD
VOUT1 5
CIN
VOUT2 6
4 SDA
VOUT3 7
3
SCL
2
GND
8 S3/EN
V1
VIN2
REFIN
COUT2
DC/DC
Converter
V2
VIN3
REFIN
COUT3
DS9403-01 April 2011
DC/DC
Converter
DC/DC
Converter
V3
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1
RT9403
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
VDD
Power Supply Input. Default connected to 5V.
2
GND
Ground.
3
SCL
Serial Clock Input. This pin receives I C serial bus clock signal.
4
SDA
Serial Data Input. This pin is input or output of I C serial bus data signal.
5
VOUT1
I C Programmed VTT Output Voltage. Default = 1.1V
6
VOUT2
I C Programmed PCH_CORE Output Voltage. Default = 1.05V
7
VOUT3
I C Programmed DDR Output Voltage. Default = 1.5V
8
S3/EN
2
2
2
2
2
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.
Function Block Diagram
VDD
POR
DAC1
7 bit
VOUT1
DAC2
7 bit
VOUT2
DAC3
7 bit
VOUT3
S3/EN
2
I C
Interface
SCL
Control and
Monitoring Unit
SDA
GND
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2
DS9403-01 April 2011
RT9403
Table 1. DAC1/DAC2 Serial Code Table
SVID6
SVID5
SVID4
SVID3
SVID2
SVID1
SVID0
Output Voltage ( V )
0
0
0
0
0
0
0
2.1875
0
0
0
0
0
0
1
2.1750
0
0
0
0
0
1
0
2.1625
0
0
0
0
0
1
1
2.1500
0
0
0
0
1
0
0
2.1375
0
0
0
0
1
0
1
2.1250
0
0
0
0
1
1
0
2.1125
0
0
0
0
1
1
1
2.1000
0
0
0
1
0
0
0
2.0875
0
0
0
1
0
0
1
2.0750
0
0
0
1
0
1
0
2.0625
0
0
0
1
0
1
1
2.0500
0
0
0
1
1
0
0
2.0375
0
0
0
1
1
0
1
2.0250
0
0
0
1
1
1
0
2.0125
0
0
0
1
1
1
1
2.0000
0
0
1
0
0
0
0
1.9875
0
0
1
0
0
0
1
1.9750
0
0
1
0
0
1
0
1.9625
0
0
1
0
0
1
1
1.9500
0
0
1
0
1
0
0
1.9375
0
0
1
0
1
0
1
1.9250
0
0
1
0
1
1
0
1.9125
0
0
1
0
1
1
1
1.9000
0
0
1
1
0
0
0
1.8875
0
0
1
1
0
0
1
1.8750
0
0
1
1
0
1
0
1.8625
0
0
1
1
0
1
1
1.8500
0
0
1
1
1
0
0
1.8375
0
0
1
1
1
0
1
1.8250
0
0
1
1
1
1
0
1.8125
0
0
1
1
1
1
1
1.8000
0
1
0
0
0
0
0
1.7875
0
1
0
0
0
0
1
1.7750
0
1
0
0
0
1
0
1.7625
0
1
0
0
0
1
1
1.7500
0
1
0
0
1
0
0
1.7375
0
1
0
0
1
0
1
1.7250
0
1
0
0
1
1
0
1.7125
0
1
0
0
1
1
1
1.7000
To be continued
DS9403-01 April 2011
www.richtek.com
3
RT9403
Table 1. DAC1/DAC2 Serial Code Table
SVID6
SVID5
SVID4
SVID3
SVID2
SVID1
SVID0
Output Voltage ( V )
0
1
0
1
0
0
0
1.6875
0
1
0
1
0
0
1
1.6750
0
1
0
1
0
1
0
1.6625
0
1
0
1
0
1
1
0
1
0
1
1
0
0
1.6375
0
1
0
1
1
0
1
1.6250
0
1
0
1
1
1
0
1.6125
0
1
0
1
1
1
1
1.6000
0
1
1
0
0
0
0
1.5875
0
1
1
0
0
0
1
1.5750
0
1
1
0
0
1
0
1.5625
0
1
1
0
0
1
1
1.5500
0
1
1
0
1
0
0
1.5375
0
1
1
0
1
0
1
1.5250
0
1
1
0
1
1
0
1.5125
0
1
1
0
1
1
1
1.5000
0
1
1
1
0
0
0
1.4875
0
1
1
1
0
0
1
1.4750
0
1
1
1
0
1
0
1.4625
0
1
1
1
0
1
1
1.4500
0
1
1
1
1
0
0
1.4375
0
1
1
1
1
0
1
1.4250
0
1
1
1
1
1
0
1.4125
0
1
1
1
1
1
1
1.4000
1
0
0
0
0
0
0
1.3875
1
0
0
0
0
0
1
1.3750
1
0
0
0
0
1
0
1.3625
1
0
0
0
0
1
1
1.3500
1
0
0
0
1
0
0
1.3375
1
0
0
0
1
0
1
1.3250
1
0
0
0
1
1
0
1.3125
1
0
0
0
1
1
1
1.3000
1
0
0
1
0
0
0
1.2875
1
0
0
1
0
0
1
1.2750
1
0
0
1
0
1
0
1.2625
1
0
0
1
0
1
1
1.2500
1
0
0
1
1
0
0
1.2375
1
0
0
1
1
0
1
1.2250
1
0
0
1
1
1
0
1.2125
1
0
0
1
1
1
1
1.2000
1.6500
To be continued
www.richtek.com
4
DS9403-01 April 2011
RT9403
Table 1. DAC1/DAC2 Serial Code Table
SVID6
SVID5
SVID4
SVID3
SVID2
SVID1
SVID0
Output Voltage ( V )
1
0
1
0
0
0
0
1.1875
1
0
1
0
0
0
1
1.1750
1
0
1
0
0
1
0
1.1625
1
0
1
0
0
1
1
1.1500
1
0
1
0
1
0
0
1.1375
1
0
1
0
1
0
1
1.1250
1
0
1
0
1
1
0
1.1125
1
0
1
0
1
1
1
1.1000
1
0
1
1
0
0
0
1.0875
1
0
1
1
0
0
1
1.0750
1
0
1
1
0
1
0
1.0625
1
0
1
1
0
1
1
1.0500
1
0
1
1
1
0
0
1.0375
1
0
1
1
1
0
1
1.0250
1
0
1
1
1
1
0
1.0125
1
0
1
1
1
1
1
1.0000
1
1
0
0
0
0
0
0.9875
1
1
0
0
0
0
1
0.9750
1
1
0
0
0
1
0
0.9625
1
1
0
0
0
1
1
0.9500
1
1
0
0
1
0
0
0.9375
1
1
0
0
1
0
1
0.9250
1
1
0
0
1
1
0
0.9125
1
1
0
0
1
1
1
0.9000
1
1
0
1
0
0
0
0.8875
1
1
0
1
0
0
1
0.8750
1
1
0
1
0
1
0
0.8625
1
1
0
1
0
1
1
0.8500
1
1
0
1
1
0
0
0.8375
1
1
0
1
1
0
1
0.8250
1
1
0
1
1
1
0
0.8125
1
1
0
1
1
1
1
0.8000
1
1
1
0
0
0
0
0.7875
1
1
1
0
0
0
1
0.7750
1
1
1
0
0
1
0
0.7625
1
1
1
0
0
1
1
0.7500
1
1
1
0
1
0
0
0.7375
1
1
1
0
1
0
1
0.7250
1
1
1
0
1
1
0
0.7125
1
1
1
0
1
1
1
0.7000
To be continued
DS9403-01 April 2011
www.richtek.com
5
RT9403
Table 1. DAC1/DAC2 Serial Code Table
SVID6
SVID5
SVID4
SVID3
SVID2
SVID1
SVID0
Output Voltage ( V )
1
1
1
1
0
0
0
0.6875
1
1
1
1
0
0
1
0.6750
1
1
1
1
0
1
0
0.6625
1
1
1
1
0
1
1
0.6500
1
1
1
1
1
0
0
0.6375
1
1
1
1
1
0
1
0.6250
1
1
1
1
1
1
0
0.6125
1
1
1
1
1
1
1
0.6000
Note: (1) 0 : Pull Low to GND
(2) 1 : Open
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6
DS9403-01 April 2011
RT9403
Table 2. DAC3 Serial Code Table
SVID6
SVID5
SVID4
SVID3
SVID2
SVID1
SVID0
Output Voltage ( V )
0
0
0
0
0
0
0
3.3750
0
0
0
0
0
0
1
3.3500
0
0
0
0
0
1
0
3.3250
0
0
0
0
0
1
1
3.3000
0
0
0
0
1
0
0
3.2750
0
0
0
0
1
0
1
3.2500
0
0
0
0
1
1
0
3.2250
0
0
0
0
1
1
1
3.2000
0
0
0
1
0
0
0
3.1750
0
0
0
1
0
0
1
3.1500
0
0
0
1
0
1
0
3.1250
0
0
0
1
0
1
1
3.1000
0
0
0
1
1
0
0
3.0750
0
0
0
1
1
0
1
3.0500
0
0
0
1
1
1
0
3.0250
0
0
0
1
1
1
1
3.0000
0
0
1
0
0
0
0
2.9750
0
0
1
0
0
0
1
2.9500
0
0
1
0
0
1
0
2.9250
0
0
1
0
0
1
1
2.9000
0
0
1
0
1
0
0
2.8750
0
0
1
0
1
0
1
2.8500
0
0
1
0
1
1
0
2.8250
0
0
1
0
1
1
1
2.8000
0
0
1
1
0
0
0
2.7750
0
0
1
1
0
0
1
2.7500
0
0
1
1
0
1
0
2.7250
0
0
1
1
0
1
1
2.7000
0
0
1
1
1
0
0
2.6750
0
0
1
1
1
0
1
2.6500
0
0
1
1
1
1
0
2.6250
0
0
1
1
1
1
1
2.6000
0
1
0
0
0
0
0
2.5750
0
1
0
0
0
0
1
2.5500
0
1
0
0
0
1
0
2.5250
0
1
0
0
0
1
1
2.5000
0
1
0
0
1
0
0
2.4750
0
1
0
0
1
0
1
2.4500
0
1
0
0
1
1
0
2.4250
0
1
0
0
1
1
1
2.4000
To be continued
DS9403-01 April 2011
www.richtek.com
7
RT9403
Table 2. DAC3 Serial Code Table
SVID6
SVID5
SVID4
SVID3
SVID2
SVID1
SVID0
Output Voltage ( V )
0
1
0
1
0
0
0
2.3750
0
1
0
1
0
0
1
2.3625
0
1
0
1
0
1
0
2.3500
0
1
0
1
0
1
1
2.3375
0
1
0
1
1
0
0
2.3250
0
1
0
1
1
0
1
2.3125
0
1
0
1
1
1
0
2.3000
0
1
0
1
1
1
1
2.2875
0
1
1
0
0
0
0
2.2750
0
1
1
0
0
0
1
2.2625
0
1
1
0
0
1
0
2.2500
0
1
1
0
0
1
1
2.2375
0
1
1
0
1
0
0
2.2250
0
1
1
0
1
0
1
2.2125
0
1
1
0
1
1
0
2.2000
0
1
1
0
1
1
1
2.1875
0
1
1
1
0
0
0
2.1750
0
1
1
1
0
0
1
2.1625
0
1
1
1
0
1
0
2.1500
0
1
1
1
0
1
1
2.1375
0
1
1
1
1
0
0
2.1250
0
1
1
1
1
0
1
2.1125
0
1
1
1
1
1
0
2.1000
0
1
1
1
1
1
1
2.0875
1
0
0
0
0
0
0
2.0750
1
0
0
0
0
0
1
2.0625
1
0
0
0
0
1
0
2.0500
1
0
0
0
0
1
1
2.0375
1
0
0
0
1
0
0
2.0250
1
0
0
0
1
0
1
2.0125
1
0
0
0
1
1
0
2.0000
1
0
0
0
1
1
1
1.9875
1
0
0
1
0
0
0
1.9750
1
0
0
1
0
0
1
1.9625
1
0
0
1
0
1
0
1.9500
1
0
0
1
0
1
1
1.9375
1
0
0
1
1
0
0
1.9250
1
0
0
1
1
0
1
1.9125
1
0
0
1
1
1
0
1.9000
1
0
0
1
1
1
1
1.8875
To be continued
www.richtek.com
8
DS9403-01 April 2011
RT9403
Table 2. DAC3 Serial Code Table
SVID6
SVID5
SVID4
SVID3
SVID2
SVID1
SVID0
Output Voltage ( V )
1
0
1
0
0
0
0
1.8750
1
0
1
0
0
0
1
1.8625
1
0
1
0
0
1
0
1.8500
1
0
1
0
0
1
1
1.8375
1
0
1
0
1
0
0
1.8250
1
0
1
0
1
0
1
1.8125
1
0
1
0
1
1
0
1.8000
1
0
1
0
1
1
1
1.7875
1
0
1
1
0
0
0
1.7750
1
0
1
1
0
0
1
1.7625
1
0
1
1
0
1
0
1.7500
1
0
1
1
0
1
1
1.7375
1
0
1
1
1
0
0
1.7250
1
0
1
1
1
0
1
1.7125
1
0
1
1
1
1
0
1.7000
1
0
1
1
1
1
1
1.6875
1
1
0
0
0
0
0
1.6750
1
1
0
0
0
0
1
1.6625
1
1
0
0
0
1
0
1.6500
1
1
0
0
0
1
1
1.6375
1
1
0
0
1
0
0
1.6250
1
1
0
0
1
0
1
1.6125
1
1
0
0
1
1
0
1.6000
1
1
0
0
1
1
1
1.5875
1
1
0
1
0
0
0
1.5750
1
1
0
1
0
0
1
1.5625
1
1
0
1
0
1
0
1.5500
1
1
0
1
0
1
1
1.5375
1
1
0
1
1
0
0
1.5250
1
1
0
1
1
0
1
1.5125
1
1
0
1
1
1
0
1.5000
1
1
0
1
1
1
1
1.4875
1
1
1
0
0
0
0
1.4750
1
1
1
0
0
0
1
1.4625
1
1
1
0
0
1
0
1.4500
1
1
1
0
0
1
1
1.4375
1
1
1
0
1
0
0
1.4250
1
1
1
0
1
0
1
1.4125
1
1
1
0
1
1
0
1.4000
1
1
1
0
1
1
1
1.3875
To be continued
DS9403-01 April 2011
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9
RT9403
Table 2. DAC3 Serial Code Table
SVID6
SVID5
SVID4
SVID3
SVID2
SVID1
SVID0
Output Voltage ( V )
1
1
1
1
0
0
0
1.3750
1
1
1
1
0
0
1
1.3500
1
1
1
1
0
1
0
1.3250
1
1
1
1
0
1
1
1.3000
1
1
1
1
1
0
0
1.2750
1
1
1
1
1
0
1
1.2500
1
1
1
1
1
1
0
1.2250
1
1
1
1
1
1
1
1.2000
Note :
(1) VOUT = 1.2V to 1.375V and VOUT = 2.375V to 3.375V, Step = 25mV.
(2) VOUT = 1.375V to 2.375V, Step = 12.5mV.
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DS9403-01 April 2011
RT9403
Absolute Maximum Ratings
z
z
z
z
z
z
z
z
z
(Note 1)
Supply Voltage, VDD ------------------------------------------------------------------------------------------------------ 6.5V
Input Voltage, SCL, SDA, S3/EN -------------------------------------------------------------------------------------- 6.5V
Output Voltage, VOUT1, VOUT2, VOUT3 --------------------------------------------------------------------------------------------------------------------- 4V
Power Dissipation, PD @ TA = 25°C
SOT-23-8 -------------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2)
SOT-23-8, θJA --------------------------------------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3)
HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------
Recommended Operating Conditions
z
z
z
0.4W
250°C/W
150°C
260°C
−65°C to 150°C
2kV
200V
(Note 4)
Supply Voltage, VDD ------------------------------------------------------------------------------------------------------ 5V ± 5%
Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C
Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VDD = 5V, TA = 25°C, unless otherwise specification)
Parameter
Supply Input Voltage
Symbol
VDD
POR Threshold
Test Conditions
Min
4.75
Typ
5
Max
5.25
Unit
V
VPOR_TH
4
4.25
4.4
V
POR Hysteresis
VPOR_HYS
--
250
--
mV
Supply Input Current
IVDD
--
0.65
--
mA
VOUT ≥ 1V, IOUT = 0A
−1
--
+1
%
VOUT < 1V, IOUT = 0A
−10
--
+10
mV
Capacitive Load Only
--
70
--
dB
GBW
CL = 1nF
--
1.64
--
MHz
Slew Rate
SR
CL = 0.1μF
--
11
--
mV/μs
Impedance
ROUT
--
90
--
Ω
Output Driving Capability
IOUT
--
1.1
--
mA
−0.002
--
0.002
%/μA
VREF & DAC
DAC Output Accuracy
Under−Voltage Lockout
Hysteresis
Output Buffer
DC Gain
Bandwidth
Loading Effect Regulation
2
I C Signal
Input High Threshold
VIH
2.4
--
--
V
Input Low Threshold
VIL
--
--
0.8
V
--
--
400
k/bit/s
SCL Clock Speed
EN High Threshold
VEN_H
VDD − 0.3
--
--
V
EN Low Threshold
VEN_L
--
--
0.3
V
DS9403-01 April 2011
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11
RT9403
Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of
JEDEC 51-3 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
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12
DS9403-01 April 2011
RT9403
Typical Operating Characteristics
VOUT2 vs. Temperature
1.062
1.110
1.060
1.108
1.058
1.106
1.056
1.104
1.054
VOUT2 (V)
VOUT1 (V)
VOUT1 vs. Temperature
1.112
1.102
1.100
1.098
1.052
1.050
1.048
1.096
1.046
1.094
1.044
1.092
VDD = 5V, S3/EN = H, SDA = SCL = H
1.090
1.042
VDD = 5V. S3/EN = H, SDA = SCL = H
1.040
-50
-25
0
25
50
75
100
125
-50
-25
0
25
50
75
100
125
Temperature (°C)
Temperature (°C)
VOUT3 vs. Temperature
Star Up from VDD
1.514
1.512
VDD
(5V/Div)
1.510
VOUT3 (V)
1.508
VOUT1
(1V/Div)
1.506
1.504
1.502
VOUT2
(1V/Div)
1.500
1.498
VOUT3
(1V/Div)
1.496
1.494
COUT = 0.1μF
VDD = 5V, S3/EN = H, SDA = SCL = H
1.492
-50
-25
0
25
50
75
100
125
Time (40μs/Div)
Temperature (°C)
S3 State
Power Off from VDD
VDD
(5V/Div)
S3/EN
(5V/Div)
VOUT1
(1V/Div)
VOUT1
(1V/Div)
VOUT2
(1V/Div)
VOUT2
(1V/Div)
VOUT3
(1V/Div)
COUT = 0.1μF
Time (4μs/Div)
DS9403-01 April 2011
VOUT3
(1V/Div)
COUT = 0.1μF, S3/EN = H to L
Time (4μs/Div)
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13
RT9403
VOUT1 Ramp-Up by VID
VOUT1
(1V/Div)
VOUT1 Ramp-Down by VID
VOUT1
(1V/Div)
VOUT1 = 1 to 1.325V, COUT = 0.1μF
VOUT1 = 1.325 to 1V, COUT = 0.1μF
Time (10μs/Div)
Time (10μs/Div)
VOUT2 Ramp-Up by VID
VOUT2 Ramp-Down by VID
VOUT2
(1V/Div)
VOUT2
(1V/Div)
VOUT2 = 0.925 to 1.25V, COUT = 0.1μF
Time (10μs/Div)
Time (10μs/Div)
VOUT3 Ramp-Up by VID
VOUT3 Ramp-Down by VID
VOUT3
(1V/Div)
VOUT3
(1V/Div)
VOUT3 = 1.5 to 1.825V, COUT = 0.1μF
Time (10μs/Div)
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14
VOUT2 = 1.25 to 0.925V, COUT = 0.1μF
VOUT3 = 1.825 to 1.5V, COUT = 0.1μF
Time (10μs/Div)
DS9403-01 April 2011
RT9403
Applications Information
Output Capacitor
S3/EN Function
The output capacitance value determines the slew rate of
output voltage during voltage transition. For example, if
COUT = 0.1μF and the voltage step is 1.1V, the rising slew
The RT9403 can be enabled or set to S3 state by the
voltage of S3/EN pin. If the applied voltage of S3/EN pin is
greater than enable threshold, the RT9403 will be enabled
and all outputs ramp up to its own default preset voltage
(VOUT1 = 1.1V, VOUT2 = 1.05V, VOUT3 = 1.5V). Then the
RT9403 is available to decode the SCL and SDA inputs to
determine the programmed voltage for each output. Pulling
down this pin below the enable threshold will set the
RT9403 in S3 state. In the S3 state, both VOUT1 and VOUT2
will be turned off, only VOUT3 is active. If S3/EN goes high
again, VOUT1 and VOUT2 will return to its previous active
level. Table 3 shows the S3/EN state and output status.
rate can be calculated as the following.
I
1.1× 10 −3
Slew Rate = OUT =
= 11mV/ μs
COUT 0.1× 10 − 6
For stability consideration, the recommended minimum
output capacitance is 10nF. This capacitor should be
located as close to the output pin as possible to minimize
the PCB trace parasitic inductance and resistance.
I2C Interface
The RT9403 receives and decodes the SCL and SDA inputs
from the master using the standard I2C 2-wire interface
to program each output voltage. SCL and SDA must be
pulled-up to typically 3.3V or 5V by external pull-up
resistors with value is between 10kΩ and 20kΩ. Figure 1
shows the data format of the RT9403. After the START
bit, the I2C master sends an address byte. This address
byte includes a 7-bits long address code followed by an
eighth bit which is a data direction bit (R/W).The RT9403's
address is 01100xx and is a write-only (slave) device. After
the address byte, the following 1st Data byte determines
which DAC's output voltage will be programmed. Then,
the 2nd Data byte is written to set the target output voltage
of that selected DAC according to the VID table1 and
table2. After the STOP bit, the output voltage of the
selected DAC ramps up/down to the programmed target
level.
0
1
1
0
0
S3/EN
VOUT1
VOUT2
VOUT3
H (Enable)
Active
Active
Active
L (S3 State)
OFF
OFF
Active
The 1st Data Byte
Address Byte
START
Table 3. S3/EN State and Output Status
X
X
0
AC
K
0
0
0
X
X
X G1 G0
The 2nd Data Byte
ACK
X E06 E05 E04 E03 E02 E01 E00
ACK
Stop
Fixed for Write
G1
0
0
1
1
G0
0
1
0
1
Rail to be Programmed
VOUT1
VOUT2
VOUT3
None
Note :
1. X = Don't Care
2. E [6:0] : Follow Serial Code Table
Figure 1. RT9403 Data Transfer Format
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15
RT9403
Thermal Considerations
Layout Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature. The maximum
power dissipation depends on the thermal resistance of
IC package, PCB layout, the rate of surroundings airflow
and temperature difference between junction to ambient.
The maximum power dissipation can be calculated by
following formula :
For best performance of the RT9403, the following layout
guideline should be strictly followed
`
The input capacitor should be placed as close to VDD
pin as possible.
` The output capacitor should be placed as close to VOUT
pin as possible.
Place the input and output capacitors
as close to the IC possible
PD(MAX) = (TJ(MAX) − TA ) / θJA
Where T J(MAX) is the maximum operation junction
temperature, TA is the ambient temperature and the θJA
is the junction to ambient thermal resistance. For
recommended operating conditions specification of
RT9403, the maximum junction temperature is 125°C
and TA is the maximum ambient temperature. The junction
to ambient thermal resistance θJA is layout dependent.
For SOT-23-8 package, the thermal resistance θJA is
250°C/W on the standard JEDEC 51-3 single layer thermal
test board. The maximum power dissipation at TA = 25°C
can be calculated by following formula:
5V
GND
CIN
VDD
1
8
S3/EN
GND
2
7
VOUT3
SCL
3
6
VOUT2
SDA
4
5
VOUT1
COUT3
COUT2
COUT1
3.3V5V
GND
Figure 3. PCB Layout Guide
PD(MAX) = (125°C − 25°C ) / (250°C/W) = 0.4W for
SOT-23-8 package
The maximum power dissipation depends on operating
ambient temperature for fixed TJ(MAX) and thermal resistance
θJA. For RT9403 package, the Figure 2 of derating curve
allows the designer to see the effect of rising ambient
temperature on the maximum power dissipation allowed.
Maximum Power Dissipation (W)
0.50
Single Layer PCB
0.45
0.40
0.35
SOT-23-8
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 2. Derating Curve for RT9403 Package
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DS9403-01 April 2011
RT9403
Outline Dimension
H
D
L
C
B
b
A
A1
e
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
1.000
1.450
0.039
0.057
A1
0.000
0.150
0.000
0.006
B
1.500
1.700
0.059
0.067
b
0.220
0.500
0.009
0.020
C
2.600
3.000
0.102
0.118
D
2.800
3.000
0.110
0.118
e
0.585
0.715
0.023
0.028
H
0.100
0.220
0.004
0.009
L
0.300
0.600
0.012
0.024
SOT-23-8 Surface Mount Package
Richtek Technology Corporation
Richtek Technology Corporation
Headquarter
Taipei Office (Marketing)
5F, No. 20, Taiyuen Street, Chupei City
5F, No. 95, Minchiuan Road, Hsintien City
Hsinchu, Taiwan, R.O.C.
Taipei County, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Tel: (8862)86672399 Fax: (8862)86672377
Email: [email protected]
Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit
design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be
guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.
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17