TPD4122K

2008-08-13

10

External Parts

Typical external parts are shown in the following table.

Part

Typical

Purpose

Remarks

25 V/2.2

μF

Bootstrap capacitor

(Note 1)

0.62

Ω ± 1 % (1 W)

Current detection

(Note 2)

25 V/1000 pF

± 5 %

PWM frequency setup

(Note 3)

27 k

Ω ± 5 %

PWM frequency setup

(Note 3)

25 V/10

μF

Control power supply stability

(Note 4)

25 V/0.1

μF

(Note 4)

5.1 k

Ω

FG pin pull-up resistor

(Note 5)

Note 1: The required bootstrap capacitance value varies according to the motor drive conditions. Although the IC

must be sufficiently derated accordingly.

Do not exceed a detection current of 1 A when using the IC.

intrinsic error factor is around 10 %.

The PWM frequency is broadly expressed by the following formula. (In this case, the stray capacitance of

the printed circuit board needs to be considered.)

k

Ω.

Note 4: When using the IC, adjustment is required in accordance with the use environment. When mounting, place

as close to the base of the IC leads as possible to improve noise elimination.

Note 5: The FG pin is open drain. If the FG pin is not used, connect to the GND.

Note 6: If noise is detected on the Input signal pin, add a capacitor between inputs.

Note 7: A Hall device should use an indium antimony system.

Handling precautions

(1)

still running.

(2) The IC has a forward/reverse rotation control pin (FR). To change the rotation direction, switch the FR

the FR pin is switched while the motor is rotating, the following malfunctions may occur.

A shoot-through current may flow between the upper arm and lower arm in the output stage (IGBT)

at that moment when the motor is switched.

An over current may flow into the area where the over current protection circuit cannot detect it.

(3)

minute amounts of current. Therefore, subjecting the IC to noise when mounting it on the board may

distort the triangular wave or cause malfunction. To avoid this, attach external parts to the base of

the IC leads or isolate them from any tracks or wiring which carries large current.

(4)

The PWM of this IC is controlled by the on/off state of the high-side IGBT.

(5)

the load is released as a result of the high side being ON immediately prior to the motor being locked.

This is because, over time, the bootstrap voltage falls, the high-side voltage decrease protection

operates and the high-side output becomes OFF. In this case, since the level shift pulse necessary to

turn the high side ON cannot be generated, reboot is not possible. A level shift pulse is generated by

either the edge of a Hall sensor output or the edge of an internal PWM signal, but neither edge is

available due to the motor lock and duty 100 % command. In order to reboot after a lock, the high-side