DocID027688 Rev 3

19/28

PM8908

Application information

28

6

Application information

6.1

Output voltage setting

The output voltage, in non-tracking configuration, can be easily programmed connecting the





Therefore, the output voltage setting is easily achieved using Equation 3 to select the value

Equation 3

Figure 8. Resistor divider configuration

6.2

Droop setting

In order to reduce the necessary output capacitance amount, the PM8908 can perform the

load dependent behavior if the compensation network capacitor, CC, is avoided. The

sensed current is used for reference voltage, in the PWM comparator inverting input. So

doing, the programmed output voltage is:

Equation 4

where:

V

OUT

V

REF

1R





+

--------------------------------

=

REFIN

9

VREF

7

V

OUT

V

REFIN

V

DROOP

–

=

V

DROOP

A

CS

I

LOAD



R

DROOP

G

M



------------------------------------

=