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1

2

3

4

5

6

7

8

VSS

CLASS

UVLO

DET

RTN

PG

VDD

ILIM

Detailed Pin Description

40000

(1)

TPS2376-H

SLVS646A – SEPTEMBER 2006 – REVISED SEPTEMBER 2006

DEVICE INFORMATION (continued)

TPS2376-H

(TOP VIEW)

TERMINAL FUNCTIONS

PIN NUMBER

PIN NAME

I/O

DESCRIPTION

'76-H

Connect a resistor from ILIM to VSS to set the start-up inrush current limit. The equation

ILIM

1

O

for calculating the resistor is shown in the detailed pin description section for ILIM.

Connect a resistor from CLASS to VSS to set the classification of the powered device

CLASS

2

O

(PD). The IEEE classification levels and corresponding resistor values are shown in

Table 1.

DET

3

O

Connect a 24.9-k

Ω detection resistor from DET to VDD.

VSS

4

I

Return line on the source side of the TPS2376-H from the PSE.

RTN

5

O

Switched output side return line used as the low-side reference for the TPS2376-H load.

PG

6

O

Open-drain, power-good output, active high, referenced to RTN.

UVLO comparator input that controls pass-device turn-on and off. Connect UVLO to a

UVLO

7

I

resistor divider from VDD to VSS.

VDD

8

I

Positive line from the rectified PSE provided input.

The PowerPad must be connected to VSS. The VSS copper on the circuit board must be

PowerPad™

-

I

a large fill area to assist in heat dissipation.

The following descriptions refer to the schematic of Figure 1 and the functional block diagram.

ILIM: A resistor from this pin to VSS sets the inrush current limit per Equation 1:

recommended for compatibility with legacy power sourcing equipment (PSE).

Inrush current limiting prevents current drawn by the bulk capacitor from causing the line voltage to sag below

the lower UVLO threshold. Adjustable inrush current limiting allows the use of arbitrarily large capacitors and

also accommodates legacy systems that require low inrush currents.

The ILIM pin must not be left open or shorted to VSS.

13 V and 21 V. The classification currents specified in the electrical characteristics table include the bias current

flowing into VDD and any RTN leakage current.

A high power system will not meet the standard power CLASS ranges defined in IEEE 802.3af, which are shown

for reference in Table 1. An end-to-end high power system may either redefine the CLASS power, or dispense

with CLASS entirely.

The CLASS pin must not be shorted to ground.

5

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