S-1170 Datasheet, PDF (15/29 Pages) Seiko Instruments Inc – HIGH RIPPLE-REJECTION AND LOW DROPOUT HIGH OUTPUT CURRENT CMOS VOLTAGE REGULATOR

HIGH RIPPLE-REJECTION LOW DROPOUT HIGH OUTPUT CURRENT CMOS VOLTAGE REGULATOR
Rev.3.0_02
S-1170 Series
4. Thermal shutdown circuit
The S-1170 Series implements a thermal shutdown circuit to protect the device from damage due to
overheating. When the junction temperature rises to 150°C (typ.), the thermal shutdown circuit operates
and the regulator operation stops. When the junction temperature drops to 120°C (typ.), the thermal
shutdown circuit is released and the regulator operation resumes.
If the thermal shutdown circuit starts operating due to self-heating, the regulator operation stops and the
output voltage falls. When the regulator operation has stopped, no self-heat is generated and the
temperature of the IC is lowered. When the temperature has dropped, the thermal shutdown circuit is
released, the regulator operation resumes, and self-heat is generated again. By repeating this procedure,
the output voltage waveform forms pulses. This phenomenon, stopping and resuming the regulator
operation, continues until the internal power consumption is reduced by reducing either the input voltage
or output current or both, or the ambient temperature is lowered.
Table 7
Thermal Shutdown Circuit
Operating: 150°C (typ.)
Released: 120°C (typ.)
VOUT Pin Voltage
V_SS level
Set value
Seiko Instruments Inc.
15