STK672-740A-E

No. A1136-11/19

2. Overcurrent Detection and Overheat Detection Functions of the STK672-740A-E

Each detection function operates using a latch system and turns output off. Because a RESET signal is required to

restore output operations, once the power supply, VDD, is turned off, you must either again apply power on reset with

VDDON or apply a RESETB=High→Low→High signal.

[Overcurrent detection]

This hybrid IC is equipped with a function for detecting overcurrent that arises when the motor burns out or when there

is a short between the motor terminals.

Overcurrent detection occurs at 5.5A typ with the STK672-740A-E

Overcurrent detection begins after an interval of no detection (a dead time of 5.5

μs typ) during the initial ringing part

during PWM operations. The no detection interval is a period of time where overcurrent is not detected even if the

current exceeds IOH.

[Overheat detection]

Rather than directly detecting the temperature of the semiconductor device, overheat detection detects the temperature

of the aluminum substrate (144

°C typ).

Within the allowed operating range recommended in the specification manual, if a heat sink attached for the purpose of

reducing the operating substrate temperature, Tc, comes loose, the semiconductor can operate without breaking.

However, we cannot guarantee operations without breaking in the case of operations other than those recommended,

such as operations at a current exceeding IOH max that occurs before overcurrent detection is activated.

5.5

μs typ

IOHmax

Normal operation

Set motor

current,

IOH

PWM period

No detection interval

(5.5

μs typ)

MOSFET all OFF

Over-current detection

Operation when motor pins are shorted

Current when motor terminals are shorted