PM6644

Simplified application schematic

Doc ID 023203 Rev 1

7/35

Figure 3.

Pinout

1.1

Pin description

Table 2.

Pin description

Pin

Name

Description

1

REF

1.216 V internal reference voltage. Do not connect this pin to any external component.

2FB

Feedback input for the switching section:

If this pin is connected to VCC, OUT operates at 3.47 V (Fixed mode).

If this pin is connected to a resistive divider from OUT to GND, OUT can be adjusted

from 0.9 V to 8 V.

Switching frequency setting. Connect to VIN with a resistor to properly set the switching

frequency.

4EN

ENABLE (EN) pin. The EN pin is used to enable both the switching regulator and

internal reference. Tie to ground to shut down the device. Apply 2.1 V or more for normal

operation. If the EN pin is not used for power sequencing, tie this pin to the VIN pin.

5

GND

Power and signal ground connection.

6SW

The SW pin is the switching node of the switching regulator with integrated power

MOSFETs. Connect this pin to the inductor.

7VIN

Input voltage for the switching regulator. Bypass to GND with a 1-2.2

µF MLCC

capacitor. The VIN pin supplies current to the internal switching regulator and to the

integrated voltage generator that supplies VCC if BYP < 2.4 V.

8VCC

Output of a regulator that supplies the main switching controller. Bypass to GND with a 1

µF capacitor. An integrated voltage generator regulates at 3.8 V (when VIN> = 6 V) if

BYP< 2.4 V. When BYP > 3.2 V, the integrated voltage generator shuts down and VCC is

connected to BYP through a MOSFET switch (see Figure 18 ).

9

BYP

VCC BYPASS pin (BYP). If BYP > 3.2 V, VCC is supplied by BYP through a MOSFET

switch. Bypass to GND with a 10-100 nF capacitor.

10

REF3

Integrated 3.3 V high accuracy reference voltage. Bypass to GND with a 100 nF

capacitor. VREF3 is the voltage at REF3 pin.

EXP PAD

EXP PAD

Exposed pad. Connect to signal ground.