[AP1040]

018001836-E-01

2018/06

- 13 -



Overcurrent Protection Circuit

(OCP)

An overcurrent protection circuit is built in the output stage of the AP1040. When the current exceeding

TBLANK (2 μs/@R

TBLANK

= 22 kΩ), the output stage is turned off (OUT pin = Hi- Z).

Since this function, latches off, it is necessary to turn on the motor drive power supply voltage (VM) again

or restart the SLEEPB pin (“L”

→ “H”) for recovery.

The AP1040 can adjust the overcurrent detection time by a resistor connecting to the TBLANK pin.

The detection time can be adjusted from 1.5 to 11

μs. This detection time is obtained by the following

formula.

Ω

Ω, T

μs.

Recovery with VM restart

Recovery with SLEEPB restart

Figure 13. Overcurrent Protection Circuit Timing

Note 15. Note that there is a possibility that overcurrent protection may be repeated as latch

→ release

→ latch if latch is released while the AP1040 is still in the abnormal state after overcurrent

protection operation. It may cause heat generation or deterioration of the IC.

Note 16 When using the motor drive power supply voltage (VM) at a voltage higher than 28 V, set the

detection time of overcu

rrent protection to 1.5 μs to 6.8 μs.



Error Detection Signal

The AP1040 has an open drain FLAG pin to output an abnormality detection signal. When using the

FLAG pin, it must be pulled up to the VDC or to the external power supply (3.0 V to 5.5 V) by 100

kΩ.

The FLAG pin becomes “H” when the thermal protection or overcurrent protection circuit works. It keeps

outputting “L” level (< 0.5 Vmax) in normal condition. The FLAG pin can be open when it is not used.