S13R1 datasheet(21/49 Pages) SII

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REVERSE CURRENT PROTECTION CMOS VOLTAGE REGULATOR

Rev.1.2_00

S-13R1 Series

Seiko Instruments Inc.

6. Overcurrent protection circuit

The S-13R1 Series has an overcurrent protection circuit 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 (Ishort) when the output pin is short-circuited is internally set at approx. 30 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.

7. Thermal shutdown circuit

The S-13R1 Series has a thermal shutdown circuit to protect the device from damage due to overheat. When the

junction temperature rises to 150

°C typ., the thermal shutdown circuit operates to stop regulating. When the junction

temperature drops to 120

°C typ., the thermal shutdown circuit is released to restart regulating.

Due to self-heating of the S-13R1 Series, if the thermal shutdown circuit starts operating, it stops regulating so that

the output voltage drops. When regulation stops, the S-13R1 Series does not itself generate heat and the IC's

temperature drops. When the temperature drops, the thermal shutdown circuit is released to restart regulating, thus

the S-13R1 Series generates heat again. Repeating this procedure makes the waveform of the output voltage into a

pulse-like form. Stop or restart of regulation continues unless decreasing either or both of the input voltage and the

output current in order to reduce the internal power consumption, or decreasing the ambient temperature.

Table 14

Thermal Shutdown Circuit

VOUT Pin Voltage

Operate: 150

°C typ.

VSS level

Release: 120

°C typ.

Set value

*1. Junction temperature

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