PM6681A

Pin settings

5/12

2.2

Functions

Table 1.

Pin functions

N°

Pin

Function

1SGND1

Signal ground. Reference for internal logic circuitry. It must be connected to

the signal ground plan of the power supply. The signal ground plan and the

power ground plan must be connected together in one point near the PGND

pin.

2

COMP2

DC voltage error compensation pin for the switching section 2

3

FSEL

Frequency selection pin. It provides a selectable switching frequency,

allowing three different values of switching frequencies for the switching

sections.

4EN2

Enable input for the switching section 2.

– The section 2 is enabled applying a voltage greater than 2.4V to this pin.

– The section 2 is disabled applying a voltage lower than 0.8V.

When the section is disabled the High Side gate driver goes low and Low

Side gate driver goes high. If both EN1 and EN2 pins are low and SHDN pin

is high the device enters in standby mode.

5

SHDN

Shutdown control input.

– The device switch off if the SHDN voltage is lower than the device off

thershold (Shutdown mode)

– The device switch on if the SHDN voltage is greater than the device on

threshold.

The SHDN pin can be connected to the battery through a voltage divider to

program an undervoltage lockout. In shutdown mode, the gate drivers of the

two switching sections are in high impedance (high-Z).

6FB2

Feedback input for the switching section 2 This pin is connected to a

resistive voltage-divider from OUT2 to PGND to adjust the output voltage

from 0.9V to 3.3V.

7LDO

Adjustable internal regulator output. It can be set from 0.9V to 3.3V. LDO pin

can provide a 100mA peak current.

8OUT2

Output voltage sense for the switching section 2.This pin must be directly

connected to the output votage of the switching section.

9BOOT2

Bootstrap capacitor connection for the switching section 2. It supplies the

high-side gate driver.

10

HGATE2

High-side gate driver ouput for section 2. This is the floating gate driver

output.

11

PHASE2

Switch node connection and return path for the high side driver for the

section 2. It is also used as negative current sense input.

12

CSENSE2

Positive current sense input for the switching section 2. This pin must be

connected through a resistor to the drain of the synchronous rectifier to

obtain a positive current limit threshold for the power supply controller.

13

LGATE2

Low-side gate driver output for the section 2.

14

PGND

Power ground. This pin must be connected to the power ground plan of the

power supply.

15

LGATE1

Low-side gate driver output for the section 1.