STK681-332-E

No. A1591-11/14

2. Output short-circuit detection, Overcurrent Detection and Overheat Detection

Each detection function operates using a latch system and turns output off. To restore output operation, turn the VDD

power supply off and then on again to apply a power-on reset.

[Output Short-circuit Detection, Overcurrent Detection]

When the output pin is simply connected to the circuit GND or VCC, or when the output load is short-circuited, the

output short circuit detector must be activated and turn the output off.

Constant current PWM control can be performed by connecting a current detection resistor to pins 1, 2 and 3, and

setting the Vref pin voltage to less than 2.0V. In addition, when this current detection resistor voltage exceeds 0.48V

(typ.), the overcurrent detector is activated and shuts the output off.

[Overheat Detection]

Rather than directly detecting the temperature of the semiconductor device, overheat detection detects the temperature

of the aluminum substrate (144

°C typ).

Within the allowed operating range of IO1 (6.1A) recommended in the specifications, if a heat sink attached for the

purpose of reducing the operating substrate temperature, Tc, comes loose, the semiconductor can operate without

breaking.

However, we cannot guarantee operations without breaking in the case of operation other than those recommended,

such as operations at a current exceeding IOH max (6.1A) that occurs before overcurrent detection is activated.

3. Mitigated Curve of Package Power Loss, PdPK, vs. Ambient Temperature, Ta

Package power loss, PdPK, refers to the average internal power loss, PdAV, allowable without a heat sink.

The figure below represents the allowable power loss, PdPK, vs. fluctuations in the ambient temperature, Ta.

Power loss of up to 2.8W is allowable at Ta=25

°C, and of up to 1.5W at Ta=60°C.

Allowable power dissipation, PdPK (no heat sink) - Ambient temperature, Ta

1.0

0.5

0

080

20

40

60

100

120

PdPK - Ta

Ambient temperature, Ta -

°C

2.5

3.0

2.0

1.5

ITF02714