1998 Oct 27

14

Philips Semiconductors

Product specification

Brushless DC motor drive circuit

TDA5145TS

Table 3

Switching sequence after a reset pulse; note 1

Note

1. Z = high-impedance OFF-state; L = LOW state; H = HIGH state.

Table 4

Priority of function; note 1

Note

1. L = LOW state; H = HIGH state.

It is necessary to protect high current circuits and the output stages are protected in two ways:

• Current limiting of the ‘lower’ output transistors. The ‘upper’ output transistors use the same base current as the

conducting ‘lower’ transistor (+15%). This means that the current to and from the output stages is limited.

• Thermal protection of the six output transistors is achieved by each transistor having a thermal sensor that is active

when the transistor is switched on. The transistors are switched off when the ambient temperature becomes too high.

DIR

RESET

MOT1

MOT2

DIR

FUNCTION

H

H

Z

L

H

reset

H

L

Z

L

H

normal direction

mode sequence

HLHL

Z

HLH

Z

L

HL

Z

H

L

HL

LH

Z

HL

L

Z

H

L

H

H

L

Z

reset

L

L

H

L

Z

reverse direction

mode sequence

L

LZL

H

LLL

Z

H

LLL

H

Z

LL

Z

H

L

LL

H

Z

L

BRAKE

TEST

RESET

FUNCTION

L

L

L

normal

L

L

H

reset

L

H

L

test

L

H

H

test

H

L

L

brake

H

L

H

brake

H

H

L

brake

H

H

H

brake