L6208Q View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L6208Q' PDF : 34 Pages View PDF
Circuit description
Figure 18. Half step mode
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Figure 19. Normal drive mode
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Figure 20. Wave drive mode
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L6208Q
5.9
Non-dissipative overcurrent detection and protection
The L6208Q device integrates an overcurrent detection circuit (OCD). 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 overcurrent detection, a sensing element that delivers a small but precise
fraction of the output current is implemented with each high-side power MOSFET. 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 5.6 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.
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DocID018710 Rev 3
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