TPD4204F

2018-04-09

13

Description of Protection Function

(1) Under voltage protection

This product incorporates under voltage protection circuits to prevent the MOSFET from operating in

unsaturated mode when the VCC voltage or the VBS voltage drops.

When the VCC power supply falls to this product internal setting VCCUVD (= 11 V (typ.)), all

MOSFET outputs shut down regardless of the input. This protection function has hysteresis. When

the VCC power supply reaches 0.5 V higher than the shutdown voltage (VCCUVR (= 11.5 V (typ.))),

this product is automatically restored and the MOSFET is turned on again by the input. DIAG output

is reversed at the time of VCC under-voltage protection. When the VCC power supply is less than 7 V,

DIAG output isn't sometimes reversed. When the VBS supply voltage drops VBSUVD (= 10 V (typ.)),

the high-side MOSFET output shuts down. When the VBS supply voltage reaches 0.5 V higher than

the shutdown voltage (VBSUVR (= 10.5 V (typ.))), the MOSFET is turned on again by the input

signal.

(2) Over-current protection

This product incorporates an over-current protection circuit to protect itself against over-current at

startup or when a motor is locked. This protection function detects voltage generated in the current

detection resistor connected to the RS pin. When this voltage exceeds VR (= 0.5 V (typ.)), the MOSFET

output, which is on, temporarily shuts down after a delay time, preventing any additional current

from flowing to this product. The next all “L” signal releases the shutdown state.

(3) Thermal shutdown

This product incorporates a thermal shutdown circuit to protect itself against the abnormal state

when its temperature rises excessively.

When the temperature of this chip rises to the internal setting TSD due to external causes or internal

heat generation, all MOSFET outputs shut down regardless of the input. This protection function has

hysteresis ∆TSD (= 50 °C (typ.)). When the chip temperature falls to TSD - ∆TSD, the chip is

automatically restored and the MOSFET is turned on again by the input.

Because the chip contains just one temperature detection location, when the chip heats up due to the

MOSFET, for example, the differences in distance from the detection location in the MOSFET (the

source of the heat) cause differences in the time taken for shutdown to occur. Therefore, the

temperature of the chip may rise higher than the thermal shutdown temperature when the circuit

started to operate.

(4) SD function

SD pin is the input signal pin to shut down the internal output MOSFET. Output of all MOSFET is

shut down after delay times (2 μs (typ.)) when "L" signal is input to the SD pin from external circuit

(MCU etc.). It is possible to shut down IC when overcurrent and others is detected by external circuit.

Shut down state is released by all of IC input signal "L". At open state of SD pin, shut down function

can not operate.

Timing Chart of Under voltage protection

Note: The above timing chart is considering the delay time

LIN

HO

HIN

VBS

VCC

LO

DIAG

ton

toff

ton

toff