L6228Q View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L6228Q' PDF : 32 Pages View PDF
L6228Q
Circuit description
Figure 20. Wave drive mode
3
4
5
2
6
IOUTA
IOUTB
1
8
Start Up or Reset
7
CLOCK
24 6 8 2 4 6 8
D01IN1321
4.6
Non-dissipative overcurrent protection
The L6228Q 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 overcurrent detection, the external current sense resistor normally used
and its associated power dissipation are eliminated. Figure 21 shows a simplified schematic
of the overcurrent detection circuit.
To implement the overcurrent detection, a sensing element delivering a small but precise
fraction of each high-side MOSFET current is integrated. 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 current IREF. When the output current reaches the
detection threshold (typically 2.8 A) the OCD comparator signals a fault condition. When a
fault condition is detected, the EN pin is pulled below the turn-off threshold (1.3 V typical) by
an internal open drain MOSFET with a pull down capability of 4 mA. 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.
Doc ID 14321 Rev 5
19/32
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