Datasheet

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.
3T
ON
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.