PDF《PM8908》

4 5/28 PM8908 Typical application circuit and block diagram

28 1.2 Block diagram Figure 3. Block diagram COT CONTROL LOGIC, PROTECTIONS &

ADAPTIVE DEAD TIMES VCC VCC UVLO DEAD TIMES Discharge THERMAL MONITOR PM8908 PGOOD EN REF VOUT COMP REFIN PGND PHASE BOOT VIN GND SS PHASE VCC MODE Voltage Reference Delay VOUT Hy Hy REFIN -16% REFIN +16% CL Current Limit K OV UV REFIN -30% REFIN +20% VOUT PGND Pin description and connection diagrams PM8908 6/28 DocID027688 Rev

4 2 Pin description and connection diagrams Figure 4. Pin connection (top view) Pin description

1 2

3 4 PM8908 PGND VIN PHASE

12 15

14 13

18 19

16 17 BOOT EN MODE PGOOD COMP

10 9

8 REFIN VOUT REF

7 5

11 6

20 PGND PGND VIN VCC GND PHASE PHASE PHASE PHASE Table 2. Pin description Pin Function No. Name

1 PGND Power ground connection, connected to the embedded low-side MOSFET source. Connect to the PGND PCB plane. See Figure 1.

2 3

4 VIN Power input voltage, connected to the embedded high-side MOS drain. Supply range is from

1 V to 3.5 V. Bypass VIN pins to PGND pins close to the IC package with high quality MLCC capacitors. See Figure 1.

5 6 GND All the internal references are referred to this pin. Connect to the PCB signal ground.

7 REF Reference output. Connect a

1 ?F MLCC capacitor to GND. See Figure 1.

8 COMP Error amplifier output. Connect with RF - CF to the REF pin for loop compensation. See Figure 1.

9 REFIN Reference input. Apply a voltage between 0.5 to 2.0 V. Filter with at least 0.01 ?F MLCC capacitors to GND.

10 VOUT Output voltage sense. DocID027688 Rev

4 7/28 PM8908 Pin description and connection diagrams

28 11 PHASE Output inductor connection. The pins are connected to the embedded MOSFETs (high-side source and low-side drain). Connect directly to the output inductor. See Figure 1.

12 13

14 15

16 BOOT Bootstrap pin. It provides power supply for the floating high-side MOS driver. Connect with 0.1 ?F to PHASE. See Figure 1.

17 EN Enable.

18 MODE Switching frequency and the OCL programming pin. See Table

6 on page 14. This pin must not be left floating.

19 PGOOD Power Good pin. Open drain output set free after SS has finished and pulled low when VOUT is out of the PGOOD window or any protection is triggered. Pull up to VCC, if not used it can be left floating.

20 VCC Device power supply. Operative voltage is 5.0 V. Filter with at least

1 ?F MLCC vs. GND. Thermal pad The thermal pad of the device. Connect to the PCB ground plane with multiple VIAS. Table 2. Pin description (continued) Pin Function No. Name Thermal data PM8908 8/28 DocID027688 Rev

4 3 Thermal data Table 3. Thermal data Symbol Parameter Value Unit RthJA Thermal resistance junction to ambient (Device soldered on demonstration board)

40 °C/W TMAX Maximum junction temperature

150 °C TSTG Storage temperature range -55 to

150 °C TJ Junction temperature range -40 to

150 °C DocID027688 Rev

4 9/28 PM8908 Electrical specifications

28 4 Electrical specifications 4.1 Absolute maximum ratings Note: Absolute maximum ratings are those values beyond which damage to the device may occur. These are stress ratings only and functional operation of the device at these conditions is not implied. Exposure to absolute maximum rated conditions for extended periods may affect device reliability. All voltage values are with respect to the network ground terminal. Table 4. Absolute maximum ratings Symbol Parameter Value(1) 1. All voltages need to be lower than VCC under any condition. Unit VCC To PGND, GND -0.3 to