S1142A Datasheet, PDF (14/32 Pages) Seiko Instruments Inc – HIGH-WITHSTAND VOLTAGE LOW CURRENT CONSUMPTION

HIGH-WITHSTAND VOLTAGE LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR
S-1142A/B Series
Rev.4.2_00
3. ON / OFF pin
This pin starts and stops the regulator.
When the ON / OFF pin is set to the OFF level, the entire internal circuit stops operating, and the built-in P-channel
MOS FET output transistor between the VIN pin and the VOUT pin is turned off, reducing current consumption
significantly. The VOUT pin is set to the V_SS level by the internal dividing resistor of several MΩ between the VOUT
pin and the VSS pin.
Note that the current consumption increases when a voltage of 0.3 V to V_IN − 0.3 V is applied to the ON / OFF pin.
The ON / OFF pin is configured as shown in Figure 12. Since the ON / OFF pin is neither pulled down nor pulled up
internally, do not use it in the floating status. 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 the B type.
Product Type
A
A
B
B
ON / OFF Pin
"L": ON
"H": OFF
"L": OFF
"H": ON
Table 8
Internal Circuit VOUT Pin Voltage
Operate
Set value
Stop
Stop
Operate
V_SS level
V_SS level
Set value
Current Consumption
I_SS1
I_SS2
I_SS2
I_SS1
VIN
ON / OFF
VSS
Figure 12
4. Overcurrent protection circuit
The S-1142A/B Series includes an overcurrent protection circuit which having the characteristics shown in
"1. Output voltage vs. Output current (When load current increases) (Ta = +25°C)" in " Characteristics
(Typical Data)", in order to protect the output transistor against an excessive output current and short circuiting
between the VOUT pin and the VSS pin. The current when the output pin is short-circuited (I_short) is internally set at
approx. 80 mA typ., and the normal 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 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.
14
Seiko Instruments Inc.