LOW CURRENT CONSUMPTION HIGH RIPPLE-REJECTION LOW DROPOUT CMOS VOLTAGE REGULATOR
Rev.2.3_01
S-1312 Series
6. Overcurrent protection circuit
The S-1312 Series includes 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 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-1312 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-1312 Series, if the thermal shutdown circuit starts operating, it stops regulating so that the
output voltage drops. When regulation stops, the S-1312 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-1312 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
Operate: 150°C typ.*1
Release: 120°C typ.*1
VOUT Pin Voltage
VSS level
Set value
*1. Junction temperature
21
SII [ SEIKO INSTRUMENTS INC ]
