S1721 datasheet(23/42 Pages) SII

23 / 42 page

SUPER-SMALL PACKAGE 2-CIRCUIT HIGH RIPPLE-REJECTION LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR

Rev.2.0_00

S-1721 Series

Seiko Instruments Inc.

4. Overcurrent protector

The S-1721 Series has a built-in overcurrent protector having the characteristics shown in (1) Output Voltage vs.

Output Current (Ta = 25

°C) in “ Characteristics (Typical Data) (Per Circuit)” to protect the output transistor

against an excessive output current and short circuiting between the VOUT and VSS pin.

The current (Ishort) when the output pin is short-circuited is internally set at approximately 150 mA (Typ.), and the

initial value is restored for the output voltage, if releasing a short circuit once.

Caution

Note that the overcurrent protect circuit does not provide a thermal protection function, therefore

pay attention to the conditions of input voltage and load current so that the IC’s loss under the

usage conditions, including the short circuit conditions, does not exceed the package power

dissipation if the condition in which a short circuiting or large current state (150 mA or more)

continues for a long time.

5. Pull-down/pull-up resistor (S-1721 Series A, B, C, and D types)

In the S-1721 Series A, B, C, and D types, the ON/OFF pin is internally pulled up to VIN or pulled down to VSS, so

the VOUT pin is in the VSS level when in the floating status.

In A/B (1ch only) and C (2ch only), the ON/OFF pin is connected to VIN,

In B (2ch only)/C (1ch only)/D type, the ON/OFF pin is connected to VSS;

Note that during operation in these cases, the current consumption of the IC is generated as much as the current

which flows into a pull-up resistor of 2.6 M

Ω or a pull-down resistor of 2.6 MΩ.

S1721 Datasheet(PDF) 23 Page - Seiko Instruments Inc