LB1980H

No.5974-5/7

Pin Function

Pin No.

Pin Name

Function

Equivalent circuit

27

28

1

UOUT

VOUT

WOUT

U phase output, Spark killer diodes are built-in.

V phase output, Spark killer diodes are built-in.

W phase output, Spark killer diodes are built-in.

4

5

Rf

(SENSE)

Rf

(PWR)

Output current detection. The control block current limiter

operates using the resistor Rf connected between these

pins and ground. Also, the lower side saturation

prevention circuit and the torque ripple correction circuit

operate based on the voltages across this resistor. It is

especially important to note that, since the saturation

prevention level is set using this voltage, the lower side

saturation prevention circuit will become less effective in

the high current region if the value of Rf is lowered

excessively. Also, the PWR and SENSE pins must be

connected together.

22

VS

Output block power supply

150

μA

VS

VCC

OUT

Rf (PWR)

Rf (SENSE)

30k

Ω

200

Ω

200

Ω

Lower side saturation

prevention circuit input block

10

μA

VCC

22

1

28

27

24

4

5

GSENSE

Ground sensing. The influence of the common ground

impedance on Rf can be excluded by connecting this pin

to nearest ground for the Rf resistor side of the motor

ground wiring that includes Rf. (This pin must not be left

open.)

6

FR

Forward / reverse selection. The voltage applied to this

pin selects the motor direction (forward or reverse).

(Vth=2.5V at VCC=5V (typical))

23

ADJ

Used for external adjustment of the torque ripple

correction ratio. Apply a voltage externally with a

low-impedance circuit to the ADJ pin to adjust the

correction ratio. The correction ratio falls as the applied

voltage is increased, and increases as the applied voltage

decreases. The torque ripple correction ratio can be

modified by factors in the range 0 to 2 times the ratio that

applies when his pin is left open. (The pin voltage is set to

about VCC / 2 internally, and the input impedance is about

5k

Ω.)

200

μA

VCC

VCC

VCC

VCC

FR

200

Ω

1/2

VCC

10k

Ω

10k

Ω

6k

Ω

6k

Ω

500

Ω

10k

Ω

10k

Ω

ADJ

20

μA

6

23

7

GND

Ground for all circuits other than the output transistors.

The lowest potential of the output transistors is that of the

Rf pin.

8

FGIN-

Input used when the FG amplifier is used as an inverting

input. A feedback resistor must be connected between

FGOUT and this pin.

9

FGIN+

Non-inverting input used when the FG amplifier is used as

a differential input amplifier. No bias is applied internally.

5

μA

VCC

300

Ω

FGIN(+)

FGIN(−)

300

Ω

8

9

10

FGOUT

FG amplifier output. There is an internal resistive load.

14

FC

Speed control loop frequency characteristics correction.

VCC

VCC

FC

10k

Ω

2k

Ω

VCC

FGOUT

300

Ω

14

10

Continued on next page.