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L6205

NON-DISSIPATIVE OVERCURRENT PROTECTION

The L6205 integrates an Overcurrent Detection Circuit (OCD). 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 cur-

rent sense resistor normally used and its associated power dissipation are eliminated. Figure 7 shows a simpli-

fied 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-

OCD comparator signals a fault condition. When a fault condition is detected, the EN pin is pulled below the turn

off threshold (1.3V typical) by an internal open drain MOS with a pull down capability of 4mA. By using an ex-

ternal 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 7. Overcurrent Protection Simplified Schematic

tion can be easily programmed by means of the accurate thresholds of the logic inputs. It is affected whether by

be chosen according to the desired Disable Time.

are respectively 100K

Ω and 5.6nF that allow obtaining 200µs Disable Time.

+

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

OCD

COMPARATOR

TO GATE

LOGIC

INTERNAL

OPEN-DRAIN

40

Ω TYP.

+5V

µC or LOGIC

D02IN1353