Pins description and connection diagrams

PM8800

4/10

2

Pins description and connection diagrams

Figure 3.

Pins connection (top view)

2.1

Pin descriptions

VIN

RCLASS

HTSSOP-16

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

AGND

VFB

COMP

CS

nPGD

VCC

GD

GND

RT

SS

AUXII

DCCL

AUXI_IRL

VSS

Table 1.

Pin description

Pin n

Name

Function

1

RT/SYNC

Oscillator timing resistor pin and synchronization input.

An external resistor connected from RT to AGND sets the oscillator fre-

quency. This pin will also accept narrow ac-coupled synchronization

pulses from an external clock.

2SS

Soft-start input.

An external capacitor and an internal 10uA current source set the soft-

start ramp rate.

3AUXII

Auxiliary source enable pin

Use this pin to power up the DC/DC section only from the external

source. The auxiliary source can prevail over the PoE source depend-

ing on the value of the resistor between this pin and the external

source.

4VIN

System high potential input.

The diode "OR" of PoE line and auxiliary sources connected to the PD,

it is the most positive input potential.

5

RCLASS

Classification resistor pin.

Connect a classification programming resistor between this pin and

VSS.