S1313 datasheet(22/56 Pages) SII

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SUPER LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR

S-1313 Series

Rev.2.1_00

6. Overcurrent protection circuit

The S-1313 Series includes an overcurrent protection circuit which has 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 (Ishort) is internally set at approx. 50 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-1313 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-1313 Series, if the thermal shutdown circuit starts operating, it stops regulating so that the

output voltage drops. When regulation stops, the S-1313 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

this IC 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 15

Thermal Shutdown Circuit

VOUT Pin Voltage

Operate: 150

°C typ.

VSS level

Release: 120

°C typ.

Set value

*1. Junction temperature

8. Thermal shutdown circuit stop function

The S-1313 Series has a thermal shutdown circuit stop function during low load current.

When the load current is approx. 0.2 mA or less, the current that flows in the thermal shutdown circuit is stopped and

the thermal shutdown circuit stops operating. This makes the super low current consumption operation possible.

When the load current is approx. 0.5 mA or more, a current is applied to the thermal shutdown circuit, thus making the

protection operation possible.

IOUT [mA]

7.0

6.0

5.0

4.0

3.0

2.0

1.0

3.0

2.0

2.5

1.5

1.0

0.5

Thermal shutdown circuit operating

Operation at super low current consumption

Figure 21

S1313 Datasheet(PDF) 22 Page - Seiko Instruments Inc

S1313 Datasheet(HTML) 22 Page - Seiko Instruments Inc

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