Daattaasshheeeett
BD621xxx Series
c) Thermal shutdown (TSD) circuit
The TSD circuit operates when the junction temperature of the driver exceeds the preset temperature (175°C
nominal). At this time, the controller forces all driver outputs to high impedance. Since thermal hysteresis is provided
in the TSD circuit, the chip returns to normal operation when the junction temperature falls below the preset
temperature (150°C nominal). Thus, it is a self-resetting circuit.
The TSD circuit is designed only to shut the IC off to prevent thermal runaway. It is not designed to protect the IC or
guarantee its operation in the presence of extreme heat. Do not continue to use the IC after the TSD circuit is
activated, and do not operate the IC in an environment where activation of the circuit is assumed.
d) Over current protection (OCP) circuit
To protect this driver IC from ground faults, power supply line faults and load short circuits, the OCP circuit monitors
the output current for the circuit’s monitoring time (10µs, nominal). When the protection circuit detects an over
current, the controller forces all driver outputs to high impedance during the off time (290µs, nominal). The IC
returns to normal operation after the off time period has elapsed (self-returning type). At the two channels type, this
circuit works independently for each channel.
Threshold
Iout
0
CTRL Input
Internal status
Monitor / Timer
ON
mon.
OFF
ON
off timer
Fig.36 Over current protection (timing chart)
●I/O equivalent circuit
VCC
VCC
VCC
VCC
VREF
100k
100k
10k
FIN
RIN
OUT1
OUT2
OUT1
OUT2
GND
RNF
GND
Fig.37 FIN / RIN
Fig.38 VREF
Fig.39 OUT1 / OUT2
Fig.40 OUT1 / OUT2
(HSOP25)
(SOP8/HRP7)
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TSZ02201-0P2P0B300070-1-2
25.Dec.2012 Rev.002
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TSZ22111･15･001
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