S-13A1 Datasheet, PDF (32/74 Pages) Seiko Instruments Inc – HIGH RIPPLE-REJECTION LOW DROPOUT HIGH OUTPUT CURRENT CMOS VOLTAGE REGULATOR

HIGH RIPPLE-REJECTION LOW DROPOUT HIGH OUTPUT CURRENT CMOS VOLTAGE REGULATOR
S-13A1 Series
Rev.2.1_00
6. Overcurrent protection circuit
The S-13A1 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 (I_short) is internally set at approx. 200 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-13A1 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-13A1 Series, if the thermal shutdown circuit starts operating, it stops regulating so that the
output voltage drops. When regulation stops, the S-13A1 does not itself generate heat so that the IC’s temperature
drops. When the temperature drops, the thermal shutdown circuit is released to restart regulating, thus the S-13A1
Series generates heat again. Repeating this procedure makes waveform of the output voltage pulse-like form. Stop or
restart of regulation continues unless decreasing either or both of the input voltage and the output voltage in order to
reduce the internal power consumption, or decreasing the ambient temperature.
Table 19
Thermal Shutdown Circuit
VOUT Pin Voltage
Operation: 150°C typ.^*1
Release: 120°C typ.^*1
V_SS level
Set value
*1. Junction temperature
32