Designing an application with the L6230

AN4243

16/29

Doc ID 024199 Rev 1

Figure 13.

L6230 overcurrent detection simplified circuitry

This sensed current is compared to an internally-generated reference to detect an

overcurrent condition. An internal open-drain MOSFET turns on when the sum of the

currents in the bridge 1, the bridge 2 or the bridge 3 reaches the threshold (2.8 A typical

value); the open-drain is available at the DIAG-EN pin for diagnostic purposes and to ensure

an overcurrent protection, connecting an RC network (see Figure 13).

Figure 14 shows the device operating in overcurrent condition.

When an overcurrent is detected the internal open-drain MOSFET pulls the DIAG-EN pin to

GND, switching off all 6 power DMOS of the device and allowing the current to decay. Under

a persistent overcurrent condition, like a short to ground or a short between two output pins,

the external RC network on the EN pin (see Figure 13) reduces the RMS value of the output

current by imposing a fixed disable time after each overcurrent occurrence.

short-circuit condition. When the current flowing through the high-side DMOS reaches the

current begins decaying as it circulates through the freewheeling diodes. Since the DMOS

are off, there is no current flowing through them and no current to sense so the OCD circuit,

Even if the maximum output current can be very high, the external RC network provides a

+

OVER TEMPERATURE

/ n

HIGH SIDE DMOS

POWER SENSE

1 cell

POWER SENSE

1 cell

POWER SENSE

1 cell

POWER DMOS

n cells

POWER DMOS

n cells

POWER DMOS

n cells

OCD

COMPARATOR

TO GATE

LOGIC

INTERNAL

OPEN-DRAIN

40

Ω TYP.

DIAG-EN

μC or LOGIC

AM16575v1