S-814 Datasheet, PDF (13/32 Pages) Seiko Instruments Inc – LOW DROPOUT CMOS VOLTAGE REGULATOR

Rev.2.1_00
LOW DROPOUT CMOS VOLTAGE REGULATOR
S-814 Series
3. ON/OFF pin (Shutdown pin)
This pin starts and stops the regulator.
When the shutdown pin is switched to the shutdown level, the operation of all internal circuits stops, the
built-in Pch MOSFET output transistor between VIN pin and VOUT pin is shutdown, allowing current
consumption to be drastically reduced. The VOUT pin enters the Vss level due to internally divided
resistance of several MΩ between VOUT pin and VSS pin.
Furthermore, the structure of the ON/OFF pin is as shown in Figure 13. Since the ON/OFF pin is neither
pulled down nor pulled up internally, do not use it in the floating state. In addition, please note that current
consumption increases if a voltage of 0.3 V to V_IN−0.3 V is applied to the shutdown pin. When the
ON/OFF pin is not used, connect it to the VIN pin in case of the product type is ‘”A” and to the VSS pin in
case of “B”.
V_IN
ON/OFF
V_SS
Figure 13
Product type
A
A
B
B
ON/OFF pin
“H”: Power on
“L”: Shutdown
“H”: Shutdown
“L”: Power on
Table 6
Internal circuit
Operating
Stop
Stop
Operating
VOUT pin voltage
Set value
V_SS level
V_SS level
Set value
Current consumption
I_SS1
I_SS2
I_SS2
I_SS1
4. Short-circuit protection circuit
The S-814 Series incorporates a short-circuit protection circuit to protect the output transistor against
short-circuiting between VOUT pin and VSS pin.
The short-circuit protection circuit controls output current as shown in “1. Output voltage vs. Output
current (When load current increases)” curve in “„ Characteristics”, and prevents output current of
approx. 70 mA or more from flowing even if VOUT pin and VSS pin are shorted. However, the short-
circuit protection circuit does not protect thermal shutdown. Be sure that input voltage and load current do
not exceed the specified power dissipation level.
When output current is large and a difference between input and output voltages is large even if not
shorted, the short-circuit protection circuit may start functioning and the output current may be controlled
to the specified amperage. For details, refer to “3. Maximum output current vs. Input voltage” curve in
“„ Characteristics”.
Seiko Instruments Inc.
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