S-19500A03A-E8T1U4 Datasheet, PDF (27/52 Pages) Seiko Instruments Inc – CMOS VOLTAGE REGULATOR WITH WATCHDOG TIMER AND RESET FUNCTION

FOR AUTOMOTIVE 125°C OPERATION HIGH-WITHSTAND VOLTAGE CMOS VOLTAGE REGULATOR WITH WATCHDOG TIMER AND RESET FUNCTION
Rev.1.2_01
S-19500/19501 Series
1. 3 Overcurrent protection circuit
The S-19500/19501 Series includes an overcurrent protection circuit which having the characteristics shown in
"1. 1 Output voltage vs. Output current (When load current increases) (Ta = +25°C)" of "1. Regulator
block" in " Characteristics (Typical Data)", in order to limit an excessive output current and overcurrent of the
output transistor due to 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. 60 mA typ., and the load current when short-circuiting is limited
based on this value. The output voltage restarts regulating if the output transistor is released from overcurrent
status.
Caution This overcurrent protection circuit does not work as for thermal protection. If this IC long keeps
short circuiting, 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.
1. 4 Thermal shutdown circuit
The S-19500/19501 Series has a thermal shutdown circuit to limit self-heating. When the junction temperature
rises to 170°C typ., the thermal shutdown circuit operates to stop regulating. After that, when the junction
temperature drops to 135°C typ., the thermal shutdown circuit is released to restart regulating.
Due to self-heating of the S-19500/19501 Series, if the thermal shutdown circuit starts operating, it stops
regulating so that the output voltage drops. For this reason, self-heating is limited and the IC's temperature drops.
When the temperature drops, the thermal shutdown circuit is released to restart regulating, thus self-heating is
generated again due to rising of the output voltage. Repeating this procedure makes the waveform of the VOUT
pin output into a pulse-like form. This phenomenon 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.
Note that the product may suffer physical damage such as deterioration if the above phenomenon occurs
continuously.
Table 15
Thermal Shutdown Circuit
VOUT Pin Voltage
Detect: 170°C typ.^*1
Release: 135°C typ.^*1
VSS level
Set value
*1. Junction temperature
27