Circuit description

L6207Q

16/27

DocID018993 Rev 3

When the monostable times out, the lower power MOSFET is turned on again after some

delay set by the deadtime to prevent cross conduction.

Figure 13. Slow decay mode output stage configurations

5.5

Non-dissipative overcurrent detection and protection

The L6207Q 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 14 shows a simplified schematic

of the overcurrent detection circuit for bridge A. Bridge B is provided by an analogous circuit.

To implement the 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

output current reaches the detection threshold (typically 5.6 A) the OCD comparator signals

a fault condition. When a fault condition is detected, an internal open drain MOSFET with

a pull-down capability of 4 mA connected to the EN pin is turned on. Figure 15 shows the

OCD operation.

By using an external R-C on the EN pin, as shown in Figure 14, the OFF time before

recovering normal operation can be easily programmed by means of the accurate

thresholds of the logic inputs.

magnitude is reported in Figure 17.

disable time.