Obsolete

Product(s)

- Obsolete

Product(s)

STHS4257A, STHS4257A1, STHS4257L, STHS4257L1

Summary description

7/18

1.1

Pin descriptions

1.1.1

tell the PSE which power class will be connected. Leave it open for Class 0.

see Table 3.

1.1.2

This is negative return power line to PSE.

1.1.3

Power supply (GND)

This is the Power Input/Output, positive rail.

1.1.4

Signature disable input (SIGDISA)

if it is unused. Tie to GND to present an invalid signature.

Note: This signal is available for STHS4257A1 and STHS4257L1 only.

1.1.5

Power Good output (PWRGD)

This pin indicates that the STHS4257x/x1 power MOSFET is fully on and works in normal

operation mode (Power Good). Open drain, low impedance means that the power is good; in

1.1.6

This is the Power Output, negative rail.

1.2

IEEE802.3af PD power classes

Table 3.

1.

Class 4 is currently reserved and should not be used.

Class

Usage

Max. power levels

at input of PD (W)

Nominal classification

load current (mA)

(

Ω, 1%)

0

Default

0.44 to 12.95

< 5

Open

1

Optional

0.44 to 3.84

10.5

124

2

Optional

3.84 to 6.49

18.5

68.1

3

Optional

6.49 to 12.95

28

45.3

4

Reserved

40

30.9