L6730 datasheet(10/52 Pages) STMICROELECTRONICS

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Pin connections and functions

L6730 - L6730B

10/52

Doc ID 11938 Rev 3

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 (I

OCL) 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 (I

OCH) 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

The high-side driver is supplied through this pin. 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. Connect to the PCB

power ground plane.

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 GND with at least a 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.

Thermal PAD

Thermal Pad connects the silicon substrate and makes good thermal

contact with the PCB. Connect to the PCB power ground plane.

Table 4.

Pin connection (continued)

Pin n.

Name

Description

DSonLS

OCL

VALLEY

⋅

DSonHS

OCH

PEAK

⋅

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