L6730CQ datasheet(9/50 Pages) STMICROELECTRONICS

9 / 50 page

L6730C - L6730D

Pin connections and functions

9/50

OCL

A resistor connected from this pin to ground sets the valley- current-limit. The

valley current is sensed through the low-side MOSFET(s). The internal current

generator sources a current of 100

µA (IOCL) from this pin to ground through the

external resistor (ROCL). The over-current threshold is given by the following

equation:

Connecting a capacitor from this pin to GND helps in reducing the noise

injected from VCC to the device, but can be a low impedance path for the high-

frequency noise related to the GND. Connect a capacitor only to a “clean”

GND.

OCH

A resistor connected from this pin and the high-side MOSFET(s) drain sets the

peak-current-limit. The peak current is sensed through the high-side

MOSFET(s). The internal 100

µA current generator (IOCH) sinks a current from

the drain through the external resistor (ROCH). The over-current threshold is

given by the following equation:

PHASE

This pin is connected to the source of the high-side MOSFET(s) and provides

the return path for the high-side driver. This pin monitors the drop across both

the upper and lower MOSFET(s) for the current limit together with OCH and

OCL.

HGATE

This pin is connected to the high-side MOSFET(s) gate.

BOOT

Through this pin is supplied the high-side driver. Connect a capacitor from this

pin to the PHASE pin and a diode from VCCDR to this pin (cathode versus

BOOT).

PGND

This pin has to be connected closely to the low-side MOSFET(s) source in

order to reduce the noise injection into the device.

LGATE

This pin is connected to the low-side MOSFET(s) gate.

VCCDR

5V internally regulated voltage. It is used to supply the internal drivers and as a

voltage reference. Filter it to ground with at least 1µF ceramic cap.

VCC

Supply voltage pin. The operative supply voltage range is from 4.5V to 14V.

PGOOD

This pin is an open collector output and it is pulled low if the output voltage is

not within the specified thresholds (90%-110%). If not used it may be left

floating. Pull-up this pin to VCCDR with a 10K resistor to obtain a logical signal.

Table 3.

Pins connection

DSonLS

OCL

VALLEY

⋅

DSonHS

OCH

PEAK

⋅

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