AS1860 datasheet(6/51 Pages) ETC2

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AS1860

Akros Silicon, Inc.

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

408.746.9000



http://www.AkrosSilicon.com

PIN ASSIGNMENTS AND DESCRIPTIONS

Figure 1 - AS1860 Pin Assignments

Table 1 - AS1860 Signal Descriptions - Primary Side

Name

I/O1

Description

Primary-Side: PD Controller

48VIN

AS1860 startup power input.

Paddle

48RTN

Input power return. One of three bottom side device connections, 48RTN (Paddle #1) is

connected to the internal PD Power MOSFET source. 48RTN is connected to 48N (Paddle

#2) via this internal inrush current limiting power MOSFET.

Paddle

48N

Primary-side Transformer power return. One of three bottom side device connections, 48N

(Paddle #2) provides the power return for the DC-DC controller transformer primary. 48N is

connected to the internal PD Power MOSFET drain. 48N is connected to 48RTN via this

internal inrush current limiting power MOSFET.

LDET

D, I

Local Power Enable Input. Enables use of local power for the DC-DC controller and disables

PD functions. When activated this disables the PoE PD signature capability that normally

uses the RSIG signature resistor.

Refer to Figure 3 for a typical LDET circuit configuration and Table 16 for resistor values. If

Local power detection is not required, connect LDET to 48VIN. Note that LDET must NOT be

tied to 48RTN.

In Software mode, the LDET status can be read from the PD Status & Control Register.

RCLASS

PoE Classification Resistor. See Table 14 for resistor value. Connect the classification

resistor between this input and the 48RTN (Paddle #1). The resistor is automatically

disconnected after a valid PD classification.

RSIG

A, I

PoE Signature Resistor. Connect a 26.7KΩ signature resistor from RSIG to 48VIN. This

resistor is automatically disconnected after a valid PD detection.

CLIM

Sets internal PD Power MOSFET current limit in PoE operation mode; should be pulled

either High (VDD5I) or Low (48RTN). In Local Mode (LDET active), CLIM is not used.

High = VDD5I = ILIM_AT (see Electrical Characteristics)

Low = 48RTN = ILIM_AF (see Electrical Characteristics)

Primary-Side: Common Power Pins

VBP

Internal bias node, decouple with an external capacitor to VBIAS.

VBIAS

Bias voltage input (typically from a power transformer winding).

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