L6730D datasheet(25/50 Pages) STMICROELECTRONICS

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L6730C - L6730D

Device description

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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 25).

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 a lot on the layout, MOSFETs, free-wheeling

diode, switched current and input voltage. In case of good layout and medium current, the

minimum masking time can be chosen, while in case of higher noise, it’s better to select to

maximum one. Connecting Tmask pin to VCCDR the masking time is about 400ns while

connecting it to GND the resulting masking time is about 260ns.

5.10

Multifunction pin (S/O/U L6730C) (CC/O/U L6730D)

With this pin it is possible:

●

To enable-disable the sink-mode-current capability (L6730C) or the constant current

protection (L6730D) at the end of the soft-start;

●

To enable-disable the latch-mode for the OVP;

●

To set the UVLO threshold for 5V BUS and 12V BUS.

Table 6 shows how to set the different options through an external resistor divider:

Figure 20. External resistor

L6730/B

S/O/U

CC/O/U

VCCDR

L6730C/D

L6730D Arkusz danych(PDF) 25 Page - STMicroelectronics