S-1172 Seiko Instruments, S-1172 Datasheet - Page 15

• Manufacturer Part Number: S-1172
• Description: HIGH RIPPLE-REJECTION LOW DROPOUT HIGH OUTPUT CURRENT CMOS VOLTAGE REGULATOR
• Manufacturer: Seiko Instruments

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Rev.1.1
3. Shutdown pin (ON/OFF pin)
4. Overcurrent protection circuit
This pin starts and stops the regulator.
When the ON/OFF pin is set to the shutdown level, the entire internal circuit stops operating, and the built-in
P-channel MOS FET output transistor between the VIN and VOUT pin is turned off, in order to reduce the current
consumption significantly. The VOUT pin is set to the V
kΩ between the VOUT and VSS pin.
Note that the current consumption increases when a voltage of 0.3 V to 1.0 V is applied to the ON/OFF pin.
The ON/OFF pin is configured as shown in Figure 14 . Since the ON/OFF pin is neither pulled down nor pulled up
internally, do not use it in the floating state.
When not using the ON/OFF pin, connect it to the VSS pin in the product A type, and connect it to the VIN pin in B
type.
The S-1172 Series has an overcurrent protection circuit having the characteristics shown in (1) Output Voltage vs.
Output Current (When load current is increased) (Ta = 25 ° C) in “
protect the output transistor against an excessive output current and short circuiting between the VOUT and VSS
pin. The current (I
initial value is restored for the output voltage, if releasing a short circuit once.
Caution This overcurrent protection circuit does not work as for thermal protection. If this IC long keeps
_00
Logic Type
ON/OFF
A
A
B
B
short circuiting inside, pay attention to the conditions of input voltage and load current so that,
under the usage conditions including short circuit, the loss of the IC will not exceed power
dissipation of the package.
Figure 14
“H”: Power off
“H”: Power on
“L”: Power on
“L”: Power off
HIGH RIPPLE-REJECTION LOW DROPOUT HIGH OUTPUT CURRENT CMOS VOLTAGE REGULATOR
SHORT
ON/OFF Pin
) when the output pin is short-circuited is internally set at approx. 200 mA (Typ.), and the
VSS
VIN
Internal Circuits
Operate
Operate
Stop
Stop
Seiko Instruments Inc.
Table 8
VOUT Pin Voltage
SS
Set value
Set value
V
V
SS
SS
level by the internal dividing resistor of several hundred
level
level
Characteristics (Typical Data) ”, in order to
Current Consumption
I
I
I
I
SS1
SS2
SS2
SS1
S-1172 Series
15