L6228

16/26

Figure 18. Wave Drive Mode

NON-DISSIPATIVE OVERCURRENT PROTECTION

The L6228 integrates an Overcurrent Detection Circuit (OCD) for full protection. This circuit provides protection

against a short circuit to ground or between two phases of the bridge. With this internal over current detection,

the external current sense resistor normally used and its associated power dissipation are eliminated. Figure 19

shows a simplified schematic of the overcurrent detection circuit.

To implement the over current detection, a sensing element that delivers a small but precise fraction of the out-

put current is implemented with each high side power MOS. Since this current is a small fraction of the output

current there is very little additional power dissipation. This current is compared with an internal reference cur-

a fault condition. When a fault condition is detected, the EN pin is pulled below the turn off threshold (1.3V typ-

ical) by an internal open drain MOS with a pull down capability of 4mA. By using an external R-C on the EN pin,

the off time before recovering normal operation can be easily programmed by means of the accurate thresholds

of the logic inputs.

Figure 19. Overcurrent Protection Simplified Schematic

2

4

2

D01IN1321

4682468

6

8

CLOCK

35

17

Start Up or Reset

+

OVER TEMPERATURE

POWER SENSE

1 cell

POWER SENSE

1 cell

POWER DMOS

n cells

POWER DMOS

n cells

HIGH SIDE DMOSs OF

THE BRIDGE A

FROM THE

BRIDGE B

OCD

COMPARATOR

OCD

COMPARATOR

TO GATE

LOGIC

INTERNAL

OPEN-DRAIN

40

Ω TYP.

µC or LOGIC

D01IN1337