AS1138

Akros Silicon, Inc.

6399 San Ignacio Avenue, Suite 250, San Jose, CA 95119 USA

408.746.9000

www.AkrosSilicon.com

4

PIN ASSIGNMENTS AND DESCRIPTIONS

Figure 1 - AS1138 Pin Diagram

Table 1 - Pin Assignments

Pin

I/O

Name

Description

1

-

nc

No Connect

2

P

VDD48O

Switched 48V supply output

3

-

nc

No Connect

4

P

VDD48I

48 V positive bus pin, fed by the output of the external diode bridge. This bus requires the

connection of a detection signature capacitor and resistor. Refer to Detection Mode section.

5

A

GND

Must be connected to paddle ground (GND)

6

A

GND

Must be connected to paddle ground (GND)

7

A

GND

Must be connected to paddle ground (GND)

8

O

VDD5

Internal 5 volts bus decoupling point

9

A

RCURR

Current limit pin. Connection to paddle ground sets the current limit to ILIM-AF (for 13W

applications). Open circuit sets the current limit to ILIM-AT (for 30W applications).

10

A

RCLASS

Classification resistor connection

11

A

LVMODE

Local Voltage Mode. When pulled high, LVMODE opens the internal FET switch and keeps

the DC-DC controller active. This is a current-mode input pin. It should be pulled to GND

when not in use.

12

A

FB

DC-DC Controller feedback point

13

A

COMP

DC-DC Controller error amplifier compensation network connection

14

A

CSS

DC-DC Controller soft-start capacitor connection point (required).

15

A

CS

DC-DC Controller peak-current sense input (low side)

16

O

NDRV

DC-DC Controller N-MOSFET gate drive

17

O

VBN

DC-DC Controller low-side supply decoupling

18

I

FSEL

Frequency Select. This pin sets the switching frequency of the DC-DC converter.

19

O

ATDET

IEEE® 802.3at-2009 PSE detects. High level output indicates availability of higher system

power, either via connection to a Type 2 PSE, or via a local power supply.

20

-

nc

No Connect

Paddle

P

GND

Local analog ground. This is the negative output from the external diode bridge and is not

isolated from the line input.

Key:

I = Input

O = Output

A = Analog signal

P = Power