L6730 datasheet(26/52 Pages) STMICROELECTRONICS

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Device description

L6730 - L6730B

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If the current is higher than the valley OCP threshold during the off-time, the high-side

MOSFET(s) will not be turned ON. In this way the maximum current can be limited (Figure 21.).

During the constant-current-protection if the Vout becomes lower than 80% of the programmed

value an UV (under-voltage) is detected and the device enters in HICCUP mode. The under-

voltage-lock-out (UVLO) is adjustable by the multifunction pin (see Chapter 5.10 on page 27).

It’s possible to set two different thresholds:

●

4.2V for 5V Bus

●

8.6V for 12V Bus

Working with a 12V BUS, setting the UVLO at 8.6V can be very helpful to limit the input current

in case of BUS fall.

5.9

Adjustable masking time

By connecting the masking time pin to VCCDR or GND it is possible to select two different values

for the peak current protection leading edge blanking time. This is useful to avoid any false OCP

trigger due to spikes and oscillations generated at the turn-on of the high-side MOSFET(s). The

amount of this noise depends very much on the layout, MOSFETs, free-wheeling diode,

switched current, and input voltage.

When good layout and medium current are used, the minimum masking time can be chosen,

while in case of higher noise, it is better to select the maximum masking time. By connecting

the tMASK pin to VCCDR the masking time is about 400ns, while connecting it to GND results in

about 260ns masking time.

Figure 21. Valley OCP (L6730B).

VOUT

TOFF

Valley th

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