bd6232fp ROHM Co. Ltd., bd6232fp Datasheet - Page 11

• Manufacturer Part Number: bd6232fp
• Description: H-bridge Driver For Dc Brush Motor
• Manufacturer: ROHM Co. Ltd.

2) Cross-conduction protection circuit
3) Output protection circuits
In the full bridge output stage, when the upper and lower transistors are turned on at the same time, and this condition
exists during the period of transition from high to low, or low to high, a rush current flows from the power supply to
ground, resulting in a loss. This circuit protects against the rush current by providing a dead time (about 400ns,
nominal) at the transition.
a) Under voltage lock out (UVLO) circuit
b) Over voltage protection (OVP) circuit
c) Thermal shutdown (TSD) circuit
d) Over current protection (OCP) circuit
To secure the lowest power supply voltage necessary to operate the controller, and to prevent under voltage
malfunctions, a UVLO circuit has been built into this driver. When the power supply voltage falls to 5.0V (nominal)
or below, the controller forces all driver outputs to high impedance. When the voltage rises to 5.5V (nominal) or
above, the UVLO circuit ends the lockout operation and returns the chip to normal operation.
When the power supply voltage exceeds 47V (nominal), the controller forces all driver outputs to high impedance.
The OVP circuit is released and its operation ends when the voltage drops back to 43V (nominal) or below. This
protection circuit does not work in the stand-by mode. Also, note that this circuit is supplementary, and thus if it is
asserted, the absolute maximum rating will have been exceeded. Therefore, do not continue to use the IC after this
circuit is activated, and do not operate the IC in an environment where activation of the circuit is assumed.
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-returning type 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.
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.
Monitor / Timer
Internal status
CTRL Input
Threshold
Iout
0
ON
mon.
Fig.42 Over current protection (timing chart)
11/16
off timer
OFF
ON