HDMP-1637A データシートの表示（PDF） - HP => Agilent Technologies

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HDMP-1637A

Gigabit Ethernet SerDes Circuit with Differential PECL Clock Inputs

HP => Agilent Technologies 

14

VCC

VCC**

GND*

CPLLR

RXCAP0

GND_RXTTL

VCC*

VCC_RXTTL

VCC

HDMP-1637A

VCC*

GND*

GND_TXA

TOP VIEW

VCC_RXTTL

TXCAP1

CPLLT

GND_RXTTL

VCC

VCC**

*IT IS RECOMMENDED THAT THESE PINS BE CONNECTED TO THE APPROPRIATE

SUPPLY LINE, EITHER VCC OR GND, EVEN THOUGH THE PIN IS BONDED TO AN

ISOLATED PAD. REFER TO THE I/O DEFINITIONS SECTION FOR THESE PINS FOR

MORE DETAILS.

** SUPPLY VOLTAGE INTO VCC_RXA AND VCC_TXA SHOULD BE FROM A LOW NOISE

SOURCE. ALL BYPASS CAPACITORS AND PLL FILTER CAPACITORS ARE 0.1 µF.

Figure 12. Power Supply Bypass.

Startup Procedure:

The transceiver startup

procedure(s) use the following

conditions: VCC = +3.3 V +/- 5%

and REFCLK = 125 MHz +/- 100

ppm.

After the above conditions have

been met, apply valid data using

a balanced code such as 8B/10B.

Frequency lock occurs within

500 ms. After frequency lock,

phase lock occurs within 2500

bit times.

Transceiver Power

Supply Bypass and Loop

Filter Capacitors

Bypass capacitors should be used

and placed as close as possible to

the appropriate power supply

pins of the HDMP-1637A as

shown on the schematic of

Figure 12. All bypass chip

capacitors are 0.1 µF. The

VCC_RXA and VCC_TXA pins are

the analog power supply pins for

the PLL sections. The voltage

into these pins should be clean

with minimum noise. The PLL

loop filter capacitors and their

pin locations are also shown on

Figure 12. Notice that only two

capacitors are required: CPLLT

for the transmitter and CPLLR for

the receiver. Nominal

capacitance is 0.1 µF. The

maximum voltage across the

capacitors is on the order of 1

volt, so the capacitor can be a

low voltage type and physically

small. The PLL capacitors are

placed physically close to the

appropriate pins on the HDMP-

1637A. Keeping the lines short

will prevent them from picking

up stray noise from surrounding

lines or components.

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