tb6642fg TOSHIBA Semiconductor CORPORATION, tb6642fg Datasheet - Page 11

• Manufacturer Part Number: tb6642fg
• Description: Full-bridge Dc Motor Driver Ic
• Manufacturer: TOSHIBA Semiconductor CORPORATION

6.
Overcurrent Shutdown Circuit
The TB6642FG incorporates overcurrent shutdown (ISD) circuits monitoring the current that flows through
each of all the four output power transistors.
The detection time threshold is programmable through the VISD pin with a pull-up resistor. If the
overcurrent flowing through any one of the ISD circuit flows beyond the detected time threshold, all the
outputs are turned off (Hi-Z).
The detection time threshold is controllable through the external resistor of the TISD pin.
The operation recovers after stop time (toff).
Stop time is determined by oscillation frequency of OSC capacitor.
Example of formula: OSC frequency: fosc = 8/（Cosc [F] × 10
Stop time: toff = 5.17/ fosc [s] (typ.)
OSC terminal should be open in order not to recover the operation automatically after over current shut down.
Driving both the IN1 pin and IN2 pin Low allows a release of the shutdown operations; the TB6642FG
resumes the normal operation.


Detection current threshold of the external resistor, R1, of the VISD pin
10 k: 6.3 A (typ.)
20 k: 4.2A (typ.)
30 k: 3.1 A (typ.)
Detection time threshold of the external resistor, R2, of the TISD pin
10 k: 1.6 s (typ.)
20 k: 2.8 s (typ.)
100 k: 12.4 s (typ.)
IC
R1
(ISD)
VISD pin
11
TISD pin
R2
6
）[Hz] (typ.)
TB6642FG
2011-06-21