AM79C900 查看數據表（PDF） - Advanced Micro Devices

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AM79C900

Serial Interface Adapter (SIA)

Advanced Micro Devices 

X1, X2

Biased Crystal Oscillator (Input)

X1 is the input and X2 is the bypass port. When con-

nected for crystal operation, the system clock that ap-

pears at TCLK is half the frequency of the crystal

oscillator. X1 may be driven from an external source of

two times the data rate.

RF

Frequency Setting Voltage-Controlled Oscillator

(VCO) Loop Filter (Output)

This loop filter output is a reference voltage for the re-

ceive path phase detector. It also is a reference for tim-

ing noise immunity circuits in the collision and receive

enable path. Nominal reference VCO gain is 1.25 TCLK

frequency MHz/V.

PF

Receive Path VCO Phase-Locked Loop Filter (Input)

This loop filter input is the control for receive path loop

damping. Frequency of the receive VCO is internally lim-

ited to transmit frequency ±12%. Nominal receive VCO

gain is 0.25 reference VCO gain MHz/V.

TEST

Test Control (Input)

A static input that is connected to VCC for Am7992B/

Am7990 operation and to ground for testing of

Receive± path threshold and RCLK output HIGH

parameters. When TEST is grounded, RX is enabled

and RCLK is enabled except during clock acquisition,

when RCLK is HIGH.

GND1

High Current Ground

GND2

Logic Ground

GND3

Voltage-Controlled Oscillator Ground

VCC1

High Current and Logic Supply

VCC2

Voltage-Controlled Oscillator Supply

Am7992B

5

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