bd63847 ROHM Co. Ltd., bd63847 Datasheet - Page 14

• Manufacturer Part Number: bd63847
• Description: Micro Step 36v Stepper Motor Drivers
• Manufacturer: ROHM Co. Ltd.

●Protection Circuits
© 2010 ROHM Co., Ltd. All rights reserved.
BD63847/63843EFV
www.rohm.com
○Thermal Shutdown (TSD)
○Over Current Protection (OCP)
○Under Voltage Lock Out (UVLO)
○Over Voltage Lock Out (OVLO)
○Ghost Supply Prevention (protects against malfunction when power supply is disconnected)
This IC has a built-in thermal shutdown circuit for thermal protection. When the IC’s chip temperature rises above 175°C
(Typ.), the motor output becomes OPEN. Also, when the temperature returns to under 150°C (Typ.), it automatically returns
to normal operation. However, even when TSD is in operation, if heat is continued to be added externally, heat overdrive
can lead to destruction.
This IC has a built in over current protection circuit as a provision against destruction when the motor outputs are shorted
each other or VCC-motor output or motor output-GND is shorted. This circuit latches the motor output to OPEN condition
when the regulated threshold current flows for 4µs (Typ.). It returns with power reactivation or a reset of the PS terminal.
The over current protection circuit’s only aim is to prevent the destruction of the IC from irregular situations such as motor
output shorts, and is not meant to be used as protection or security for the set. Therefore, sets should not be designed to
take into account this circuit’s functions. After OCP operating, if irregular situations continues and the return by power
reactivation or a reset of the PS terminal is carried out repeatly, then OCP operates repeatly and the IC may generate heat
or otherwise deteriorate. When the L value of the wiring is great due to the wiring being long, after the over current has
flowed and the output terminal voltage jumps up and the absolute maximum values may be exceeded and as a result, there
is a possibility of destruction. Also, when current which is over the output current rating and under the OCP detection
current flows, the IC can heat up to over Tjmax=150°C and can deteriorate, so current which exceeds the output rating
should not be applied.
This IC has a built-in under voltage lock out function to prevent false operation such as IC output during power supply under
voltage. When the applied voltage to the VCC terminal goes under 15V (Typ.), the motor output is set to OPEN. This
switching voltage has a 1V (Typ.) hysteresis to prevent false operation by noise etc. Please be aware that this circuit does
not operate during power save mode. Also, the electrical angle is reset when the UVLO circuit operates during CLK-IN drive
mode.
This IC has a built-in over voltage lock out function to protect the IC output and the motor during power supply over voltage.
When the applied voltage to the VCC terminal goes over 32V (Typ.), the motor output is set to OPEN. This switching
voltage has a 1V (Typ.) hysteresis and a 4µs (Typ.) mask time to prevent false operation by noise etc. Although this over
voltage locked out circuit is built-in, there is a possibility of destruction if the absolute maximum value for power supply
voltage is exceeded, therefore the absolute maximum value should not be exceeded. Please be aware that this circuit does
not operate during power save mode.
If a signal (logic input, VREF, MTH) is input when there is no power supplied to this IC, there is a function which prevents
the false operation by voltage supplied via the electrostatic destruction prevention diode from these input terminals to the
VCC to this IC or to another IC’s power supply. Therefore, there is no malfunction of the circuit even when voltage is
supplied to these input terminals while there is no power supply.
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Technical Note
2010.4 - Rev.A