L6228 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L6228' PDF : 34 Pages View PDF
L6228
Figure 18. 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
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-
rent IREF. When the output current reaches the detection threshold (typically 2.8A) the OCD comparator signals
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
POWER SENSE
1 cell
OUT1A VSA OUT2A
HIGH SIDE DMOSs OF
THE BRIDGE A
I1A I2A
TO GATE
LOGIC
POWER SENSE
POWER DMOS
POWER DMOS
1 cell
n cells
n cells
+
µC or LOGIC
VDD
OCD
COMPARATOR
I1A / n
I2A / n
(I1A+I2A) / n
REN. EN
INTERNAL
IREF
OPEN-DRAIN
CEN.
RDS(ON)
40Ω TYP.
OVER TEMPERATURE
OCD
COMPARATOR
FROM THE
BRIDGE B
D01IN1337
16/26
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