S-19244A12H-E8T1U Datasheet, PDF (29/68 Pages) Seiko Instruments Inc – CMOS VOLTAGE REGULATOR WITH SOFT-START FUNCTION

FOR AUTOMOTIVE 105°C OPERATION LOW DROPOUT HIGH OUTPUT CURRENT CMOS VOLTAGE REGULATOR WITH SOFT-START FUNCTION
Rev.3.0_00
S-19244xxxH Series
6. Overcurrent protection circuit
The S-19244xxxH Series has a built-in overcurrent protection circuit to limit the overcurrent of the output transistor.
When the VOUT pin is shorted with the VSS pin, that is, at the time of the output short-circuit, the output current is
limited to 330 mA typ. due to the overcurrent protection circuit operation. The S-19244xxxH Series restarts
regulating when the output transistor is released from the overcurrent status.
Caution
This overcurrent protection circuit does not work as for thermal protection. For example, when
the output transistor keeps the overcurrent status long at the time of output short-circuit or
due to other reasons, pay attention to the conditions of the input voltage and the load current
so as not to exceed the power dissipation.
7. Thermal shutdown circuit
The S-19244xxxH Series has a built-in thermal shutdown circuit to limit overheating. When the junction temperature
increases to 170°C typ., the thermal shutdown circuit becomes the detection status, and the regulating is stopped.
When the junction temperature decreases to 135°C typ., the thermal shutdown circuit becomes the release status,
and the regulator is restarted.
If the thermal shutdown circuit becomes the detection status due to self-heating, the regulating is stopped and V_OUT
decreases. For this reason, the self-heating is limited and the temperature of the IC decreases. The thermal
shutdown circuit becomes release status when the temperature of the IC decreases, and the regulating is restarted
after the soft-start operation is finished, thus the self-heating is generated again. Repeating this procedure makes
the waveform of V_OUT 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.
Caution
When the heat radiation of the application is not in a good condition, the self-heating cannot be
limited immediately, and the IC may suffer physical damage. Perform thorough evaluation with
an actual application to confirm no problems happen.
Table 27
Thermal Shutdown Circuit
Release: 135°C typ.^*1
Detection: 170°C typ.^*1
VOUT Pin Voltage
Constant value^*2
Pulled down to V_SS^*3
*1. Junction temperature
*2. The constant value is output due to the regulating based on the set output voltage value.
*3. The VOUT pin voltage is pulled down to V_SS due to the feedback resistors (R_s and R_f) and a load.
29