L6730TR datasheet(8/52 Pages) STMICROELECTRONICS

8 / 52 page

Pin connections and functions

L6730 - L6730B

8/52

TMASK

The user can select two different values for the leading edge blanking time on

the peak overcurrent protection by connecting this pin to VCCDR or GND. The

device captures the analog value present at this pin at the start-up when VCC

meets the UVLO threshold.

GND

All of the internal references are referenced to this pin.

6FB

This pin is connected to the error amplifier inverting input. Connect it to Vout

through the compensation network. This pin is also used to sense the output

voltage in order to manage the over voltage conditions and the PGood signal.

7COMP

This pin is connected to the error amplifier output and used to compensate the

voltage control loop.

SS/INH

The soft-start time is programmed connecting an external capacitor from this

pin and GND. The internal current generator forces a current of 10

µA through

the capacitor. This pin is also used to inhibit the device: when the voltage at

this pin is lower than 0.5V the device is disabled.

EAREF

It is possible to set two internal references 0.6V / 1.2V or provide an external

reference from 0V to 2.5V:

–

VEAREF from 0% to 80% of VCCDR −> External Reference

–

VEAREF from 80% to 95% of VCCDR −> VREF=1.2V

–

VEAREF from 95% to 100% of VCCDR −> VREF=0.6V

An internal clamp limits the maximum VEAREF at 2.5V (typ.). The device

captures the analog value present at this pin at the start-up when VCC meets

the UVLO threshold.

OSC

Connecting an external resistor from this pin to GND, the external frequency

can be increased according with the following equation:

Connecting a resistor from this pin to VCCDR (5V), the switching frequency can

be lowered according with the following equation:

If the pin is left open, the switching frequency is 400 KHz. Normally this pin is at

a voltage of 1.2V. In OVP the pin is pulled up to 4.5V (only in latched mode).

Don’t connect a capacitor from this pin to GND.

Table 3.

Pins connection

)

(

400

Ω

⋅

KHz

Fsw

OSC

)

(

400

Ω

⋅

−

KHz

Fsw

OSC

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