A6300
AiT Semiconductor Inc.
www.ait-ic.com
LOW DROPOUT VOLTAGE REGULATOR
300mA CMOS WITH ENABLE PIN
Current Limit and Thermal Protection
The A6300 includes a current limit which monitors and controls the pass transistor’s gate voltage limiting the
output current to 350mA Typ. Thermal-overload protection limits total power dissipation in the A6300. When
the junction temperature exceeds TJ = +150℃, the thermal sensor signals the shutdown logic turning off the
pass transistor and allowing the IC to cool. The thermal sensor will turn the pass transistor on again after the
IC’s junction temperature cools by 30℃, resulting in a pulsed output during continuous thermal=overload
conditions. Thermal-overload protection is designed to protect the A6300 in the event of fault conditions. Do
not exceed the absolute maximum junction-temperature rating of TJ = +150℃ for continuous operation. The
output can be shorted to ground for an indefinite amount of time without damaging the part by cooperation of
current limit and thermal protection.
Thermal Considerations
Thermal protection limits power dissipation in A6300. When the operation junction temperature exceeds
150℃, the OTP circuit starts the thermal shutdown function and turns the pass element off. The pass element
turns on again after the junction temperature cools by 30℃.
For continuous operation, do not exceed absolute maximum operation junction temperature 125℃. The
power dissipation definition in device is:
PD = (VIN-VOUT)* IOUT + VIN * IQ
The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of
surrounding airflow and temperature difference between junctions to ambient. The maximum power
dissipation can be calculated by following formula:
PD(MAX) = (TJ(MAX)-TA) / θJA
Where TJ(MAX) is the maximum operation junction temperature 125℃, TA is the ambient thermal resistance.
For recommended operating conditions specification of A6300, where TJ(MAX) is the maximum junction
temperature of the die (125℃) and TA is the operated ambient temperature. The junction to ambient thermal
resistance θJA is layout dependent.
REV1.4
- JUN 2006 RELEASED, FEB 2015 UPDATED -
16
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