LB1838M

No.3949-3/5

Vcont

IN

OUT

OUT

M

ID

VZ

VCC

VS

ID =

VZ

r

( = Constant)

Block Diagram

VCC

OUT3

VS1

OUT4

GND

Vcont

GND

ENA2

VS2

IN2

60k

Ω

80k

Ω

60k

Ω

80k

Ω

OUT1

OUT2

ENA1

IN1

60k

Ω

80k

Ω

60k

Ω

80k

Ω

Stepping

Motor

10

µF

Thermal

shutdown

Note: As long as the voltages applied to VCC, VS1, VS2, ENA1, ENA2, IN1, and IN2 are within the limits set by the

absolute maximum ratings, there are no restrictions on the relationship of each voltage level in comparison with the

others (regarding which is higher or lower). (ex. VCC = 3V, VS1, 2 = 2V, ENA = IN = 5V)

Truth Table

IN1,2

ENA1,2

OUT1,3

OUT2,4

Mode

L

H

H

L

Forward

H

H

L

H

Reverse

L

L

OFF

OFF

Standby

H

L

OFF

OFF

Standby

Vcont pin

As shown in the left diagram, the Vcont pin outputs the voltage

of the band gap Zener VZ +VF (= 1.93V).

In normal use, this pin is left open.

The drive current ID is varied by the Vcont voltage. However,

because the band gap Zener is shared, it functions as a bridge.