S-19680AAAH-K8T2U Datasheet, PDF (15/27 Pages) Seiko Instruments Inc – Current consumption during operation

Rev.1.1_00
FOR AUTOMOTIVE 105°C OPERATION CURRENT MONITOR HIGH SIDE SWITCH
S-19680 Series
5. Thermal shutdown circuit
The S-19680 Series has a built-in thermal shutdown circuit to limit overheating.
The hysteresis type or latch type can be selected for the thermal shutdown circuit.
5. 1 Hysteresis type
When the junction temperature increases to 165°C typ., the thermal shutdown circuit becomes the detection
status, and the Pch output transistor is turned off. When the junction temperature decreases to 135°C typ., the
thermal shutdown circuit becomes the release status, and the Pch output transistor is turned on again.
If the thermal shutdown circuit becomes the detection status due to self-heating, the Pch output transistor is
turned off and V_OUT decreases. For this reason, the self-heating is limited and the temperature of the IC
decreases. The thermal shutdown circuit becomes the release status when the temperature of the IC decreases,
and the Pch output transistor is turned on, generating the self-heating 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
V_DD or I_OUT 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.
5. 2 Latch type
When the junction temperature increases to 165°C typ., the thermal shutdown circuit becomes the detection
status, and the Pch output transistor is turned off. Even if the junction temperature would decrease to 135°C typ.,
the thermal shutdown circuit detection status is latched and the Pch output transistor remains in the status, OFF.
The thermal shutdown circuit detection status latch is released by using the ON / OFF pin to set the IC power-off
status or lowering the power supply voltage to change the low power supply voltage detection circuit to the
detection status.
Set the power supply voltage 0.5 V or lower in order to change the low power supply voltage detection circuit to
the detection status.
Caution 1. When a steep fluctuation of the power supply occurs, the thermal shutdown circuit may become
the detection status even if the junction temperature would not reach 165°C typ., so pay enough
attention to the power supply voltage to ensure stable status sufficiently. Perform thorough
evaluation using the actual application.
2. If the OUT pin is steeply shorted with GND, a negative voltage exceeding the absolute maximum
ratings may occur in the OUT pin due to resonance phenomenon of the inductance and the
capacitance including C_L on the application. When a negative voltage exceeding the absolute
maximum rating occurs, the thermal shutdown circuit may become the detection status even if
the junction temperature would not reach 165°C typ. If V_OUT does not rise when the short-circuit is
eliminated after the OUT pin is steeply shorted with the GND, release the detection status latch
with the method shown in "5. 2 Latch type".
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