S-8331 Seiko Instruments USA, S-8331 Datasheet - Page 18

• Manufacturer Part Number: S-8331
• Description: Step-Up Switching Regulator (DC/DC Converter ICs)
• Manufacturer: Seiko Instruments USA

18
STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL SWITCHING REGULATOR
S-8330/8331 Series
VDIN
VCLK
VSTRB
Output Voltage
±1/2LSB
(V)
3. Electric Volume
The S-8330/31 series incorporates an electric volume with an 8-bit shift register and an 8-bit latch. The
output voltage is variable in the width of 12 V. The output voltage can be held in the data transmission
mode because the data read in the shift register is fetched into the latch by unshyncronized strobe
input. Figure 9 shows a block diagram and timing charts .
VDIN: Inputs data to the electric volume.
VCLK: Inputs clock to the electric volume.
VSTRB: Inputs strobe signal.
0
1
RESET
”Data 1” is input at “H”level; ”Data 0” is input at ”Low” level.
Fetches data at VDIN pin into the shift register at the rising edge of clocks. When clocks of
over 8 bits are input, the read data is shifted in succession for each clock, and data
corresponding to 8 bits which was input lastly is valid.
The contents of the shift register are latched by turning the strobe signal to ”H”. When the
data fetched into the latch is directly transmitted to the electric volume, the output voltage
changes. Data in the latch is held by turning the strobe signal to ”L”.
Figure 10 Linearity Accuracy
Shift Register
Volume
Electric
Latch
8-bit
8-bit
127
128
Figure 9 Block Diagram and Timing
VOUT
VOUT
VCLK
VSTRB
VDIN
Seiko Instruments Inc.
254
255
Reset
±1/2LSB
(±23.5mV)
Min. value
Data (DEC)
Volume
Hold
Electric
(MSB)
D7
±2LSB
(±93.8mV)
D6
The electric volume has 8-bit resolution.
An error in linearity may exceed ±1/2LSB
(±23.5 mV) only before or after data
changeover of 127←→128
(01111111←→10000000) (see Figure 9).
The error in linearity corresponds to 6 bits
(±93.8 mV) when used in the 12 V variable
range.
In an application where the variable range
of output voltage is 6 V or less, it is
possible to use it with high linearity
accuracy with appropriate product
selection. For example, if you want to
change output voltage within the range
from 12 V to 18 V, select the S-8330A24FS
and use it within the range of 0 ←→ 127
(00000000 ←→ 01111111). If so, high
linearity accuracy (within±1/2LSB) can be
obtained.
D5
D4
D3
D2
D1
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(LSB)
D0
Rev.5.1
Read
Setting
value
Hold
_00