PM6681ATR datasheet(27/47 Pages) STMICROELECTRONICS

27 / 47 page

PM6681A

Device description

27/47

The adjustable linear regulator is supplied by LDO5 output. It turns on after LDO5 power up

sequence.

It can provide up to 100 mA peak current. Set up the feedback resistor divider according to

the following formula, to regulate a voltage from 0.9 V to 3.3 V.

Equation 12

where LDO is the desired output voltage, Vr = 0.9 V is the internal reference voltage and Rup

and Rdown are the resistors of the feedback divider, as shown in Figure 38:

Figure 38.

LDO linear regulator

Bypass LDO5 and LDO output with 1-10

µF ceramic capacitor and a 4,7 µF tantalum

capacitor (ESR

≥ 2 Ω).

Table 8.

V5SW multifunction pin

V5SW

Description

GND

The 5 V linear regulator is always turned on and supplies LDO5 output.

Switching 5 V

output

The 5 V linear regulator is turned off when the voltage on V5SW is above 4.8 V and

LDO5 output is supplied by the switching 5 V output.

External 5 V

supply

The 5 V linear regulator is turned off when the voltage on V5SW is above 4.8 V and

LDO5 output is supplied by the external 5 V.

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

down

LDO

PM6681ATR Datasheet(PDF) 27 Page - STMicroelectronics