S-8331 Seiko Instruments USA, S-8331 Datasheet - Page 17

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

Rev.5.1
The power off pin is configured as shown in Figure 8. DO NOT use this circuit under the floating state
because the power off pin is not internally pulled up nor pulled down. If 0.4 V to 2.4 V when V
0.4 V to 1.6 V when V
When the power off pin is not used, connect it to V
The power off pin is not provided with hysteresis.
2. Power off pin (
This pin stops and starts set up operation.
Turnig the power off pin to “L” stops the operation of the internal circuits excluding the electric volume,
minimizes current consumption and short-curcuits V
and a diode at the input side into V
Figure 7 shows a circuit example using the NEC 2SJ356 (Pch MOS FET) as a current cutting switch.
This circuit example turns ON and OFF the 2SJ356 in connection with the reset signal to the power off
pin using a small signal transistor M
clamping voltage so as not to apply high voltage (20V or more) of the rated voltage between the gate
and the source of the 2SJ356. However, when the circuit is used at 20 V or below, a Zenor diode is not
needed. Invalid current flowing into resistors R
Set R
occurs in resistor R
function.
measured without attaching a current cutting switch and is different from that shown in this example).
Power off pin
_00
A
, R
“H”
“L”
B
to the maximum level. If you set the resistance of R
Be careful (Note that the efficiency characteristics shown in the reference data were
V
IN
STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL SWITCHING REGULATOR
ON
L
A
due to off current of M
/
Operation
CR OSC
OFF
CONT
IN
Stop
< 3.0V are applied, current consumption increases. DO NOT apply voltage.
Figure 7 Circuit Example Using 2SJ356
pin)
V
SS
RESET
SS
. Therefore, a switch to cut off the current is needed.
N
Seiko Instruments Inc.
Output voltage
Setting value
(Nch MOS FET). A Zenor diode (ZD) is used for the purpose of
V
SBD
N
SS
and the current cutting switch 2SJ356 does not normally
A
, R
IN
B
ON/OFF
pin.
OUT
V
during step-up operation may affect the efficiency.
OUT
pin to V
R
500kΩ
A
ON/OFF
:
A
ZD:15V
SS
to the high value, a drop in the voltage
. At this time, current flows via coils
2SJ356
R
M
Figure 8
B
N
:1MΩ
S-8330/8331 Series
VIN
VSS
+
−
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CL
IN
≥ 3.0 V,
17