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F

Absolute maximum ratings (Ta = 25

_

C)

F

Recommended operating conditions (Ta = 25

_

C)

F

Electrical characteristics (unless otherwise noted, Ta = 25

_

C and V

CC

 = 12V)

F

Electrical characteristic curves

FL8370

41

FL8370

42

Measurement circuit

FL8370

43

Circuit operation

Input / output truth table

Forward / reverse control, forced stop, and rush current
absorption are controlled by the combination of F

IN

 and

R

IN

 input states.

(1)

Forward / reverse control circuit

When F

IN

 is HIGH and R

IN

 is LOW, current flows from

OUT1 to OUT2. When F

IN

 is LOW and R

IN

 is HIGH, cur-

rent flows from OUT2 to OUT1 (refer to the truth table).
(2)

Forced stop circuit

By setting R

IN

 and F

IN

 both HIGH or both LOW, power

supply to the motor is shut down and a brake is applied
by absorbing the motor counter-electromotive force.

(3)

Rush current absorption circuit

When a high voltage (caused by such as a motor rever-
sal) is generated on OUT1 and OUT2, an internal
comparator detects the high voltage and turns on an in-
ternal circuit that absorbs rush currents.
(4)

Drive circuit

The forward direction of the motor connected between
OUT1 and OUT2 corresponds to the current flow from
OUT1 to OUT2, and the reverse direction corresponds to
the current flow from OUT2 to OUT1. The output voltage
(V

OUT

) applied to the motor is given by the equation : 

V

OUT

 (V) = V

ZD

 

 V

CE

 (sat.) = V

ZD

 

 0.2 (I

OUT

 = 100mA)

where V

ZD

 is the zener voltage of the constant voltage

diode (ZD) connected to pin 4.
If V

ref

 is left OPEN, the output voltage (V

OUT

) is given by

the equation :
V

OUT

 (V) = V

CC

1 

 V

CE

 (sat.) (PNP) 

 2V

F

 

 V

CE

 (sat.)

= V

CC

1 

 1.8 (I

OUT

 = 100mA)

Pin descriptions

FL8370

44