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www.pericom.com

07/08/15

PI3VST01

HPD signal Generator for VGA

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Parameters Description

Test Conditions

Min.

Typ.

Max.

Units

OIRR

OFF Isolation,

BIN to BOUT

f = 250MHz

-

-46

-

dB

BW

Bandwidth –3dB,

BIN to BOUT

-

2.0

-

GHz

Propagation Delay,

BIN to BOUT

-

90

-

ps

Insertion Loss for B path

with 75-Ohm load

Freq = 10MHz (VGA)

-0.3

dB

Freq = 100MHz (XGA)

-0.33

Freq = 300MHz (UXGA) -0.4

Parameters

Description

Test Conditions

Typ.

Units

Capacitance, Switch OFF

2.4

pF

Switch Capacitance between BIN and BOUT,

Switch ON

5.6

pF

Dynamic Electrical Characteristics over Operating Range

Applications

VGA-DACs in chipsets as well as video chips (MXM, GPU, DP-to-VGA, PCIe, etc.) typically dissipate about 170 mW.

The VGA standard does not have a monitor detect feature, so the DAC dissipates power whether the monitor is connected or not.

PI3VST01 provides an HPD_OUT signal that detects the presence of a monitor. This HPD_OUT signal can be routed to the

chipset, directly, or through an MPU, to turn off the VGA DAC when a monitor is not connected. Using the PI3VST01, the system

can save 170 mW when the monitor is not connected.

PI3VST01 can also be used to enable automatic switching between two monitors. Another Pericom product, PI3V724 integrates 2

monitor detection circuits with a 1:2 VGA switch and offers both automatic and manual monitor switching.

VGA Termination

PI3VST01 can support two different termination schemes:

1. Case_75//75: Reverse termination for the monitor is provided by a 75 Ohm resistor at the connector, as per the VESA VSIS

specification.

2. Case_150//75: Reverse termination for the monitor is split between a 150 Ohm resistor at the connector and a 150 Ohm resistor

at the video DAC, as required by some chipsets.

An external resistor must be supplied between the Rref pin and ground to tell the detection circuit which termination scheme is

being used. Values for this resistor are shown below.

Rref

Application Case Supported

330Kohm +/-5% Case _150//75

200Kohm +/-5% Case _75//75

15-0090