L6788A

Pins description and connection diagram

Doc ID 15341 Rev 2

7/18

16

CS2+

Channel 2 current sense positive input.

Connect through an R-C filter to the phase-side of the channel 2 inductor.

17

CS3-

Channel 3 current sense negative input.

Connect through a Rg resistor to the output-side of the channel 3 inductor.

18

CS3+

Channel 3 current sense positive input.

Connect through an R-C filter to the phase-side of the channel 3 inductor.

19

FBRTN

Feedback return.

This pin is the ground return for remote sensing the output voltage.

Connect directly to the point where the output voltage is to be regulated.

20

FB

Error amplifier inverting input pin.

Connect with a resistor RFB vs. VSEN and with an RF - CF//CP vs. COMP pin.

See reference schematic for more details.

A current proportional to the load current can be sourced (in according to

RT/DROOP pin status) from this pin in order to implement the droop effect.

See “droop function” section for details.

21

COMP

Error amplifier output. Connect with an RF - CF//CP vs. FB pin.

22

AGND

Signal ground pin. All the internal references are referred to this pin.

Connect it to the PCB signal ground (AGND).

23

VSEN

Output voltage monitor, manages OVP/UVP protections.

Connect to the positive side of the load to perform remote sense.

See “output voltage protections” section for more details.

24

RT/

DROOP

Operation frequency setting.

Internally fixed at 1.240 V it allows programming the switching frequency FSW

of each channel.

Frequency is programmed according to the Rosc resistor connected from the

pin vs. AGND with again of 9 kHz/µA. Leaving the pin floating programs a

switching frequency of 200 kHz per phase.

The device uses this pin also to enable/disable the droop function.

See “droop function“ section for details.

25

IOUT/OCP

Output current indication and over current protection setting.

The device sources from this pin a current proportional to the load current

[(DCR/Rg)*IOUT)].

Connect a resistor from this pin to AGND to program the over current

protection level.

This pin is also used as output current indication. Voltage measured at this pin

is proportional to the output current. External NTC can be used for

temperature compensation of OCP and IOUT readings. See “over current

protection “section for details.

Table 2.

Pin description (continued)

Pin n°

Name

Description