Pin Assignment

No. 5439-4/10

LB1921

Pin Functions

Pin No.

Symbol

Function

1

2

3

4

5

6

7

8

9

10

11

12

13

14

20, 19

18, 17

16, 15

21

22

23

24

25

26

27

28

5V

7V

CR

OUT1

OUT2

OUT3

GND2

F/R

S/S

IN1+, IN1–

IN2+, IN2–

IN3+, IN3–

Xtal

GND1

LD

5-V power supply

7-V power supply

Power supply for all blocks other than the output block

FG pulse input (4-V power supply)

FG pulse input

FG amplifier output

PWM oscillator frequency setting

Output 1

Output 2

Output 3

Output block ground

Forward/reverse control

Low: forward, high: reverse

Start/stop control

Low: start, high: stop

Used both as the power supply for the output block and as output current detection. The output current can be

Hall input for OUT1

Hall input for OUT2

Hall input for OUT3

Crystal oscillator connection. Connect a crystal oscillator element to this pin.

Ground for all blocks other than the output block

Lock detector

This pin goes low when the motor speed is within the lock range (±6.25%).

Speed discriminator output

Over speed

→ high

Integrator input

Integrator output (speed control)

PLL output

FG amplifier output (after the Schmitt trigger circuit)