TZA3004HL/C3 Просмотр технического описания (PDF) - Philips Electronics

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производитель

TZA3004HL/C3

SDH/SONET data and clock recovery unit STM1/4 OC3/12

Philips Electronics 

Philips Semiconductors

SDH/SONET data and clock recovery unit

STM1/4 OC3/12

Objective specification

TZA3004HL

handbook, full pagewidth

BAND GAP

REFERENCE

100 nF VEE

PC

2Ω

β > 100

POWER

CONTROL

1 kΩ

2Ω

1

kΩ

3.3

nF

1 µF

1 µH

−4.5 V

MGK141

Fig.4 Schematic diagram of TZA3004HL power control loop.

Output amplitude reference (AREF)

The voltage swing at the CML compatible output stages

DOUT, DOUTQ; COUT, COUTQ; DLOOP, DLOOPQ and

CLOOP, CLOOPQ can be controlled by adjusting the

voltage at the AREF pin. An internal voltage divider of

500 Ω and16 kΩ between GND and VEE initially fixes this

level.

In most applications the outputs will be DC coupled to a

load, which can be as low as 50 Ω (±0.20%). The output

level regulation circuit will maintain a 200 mV

peak-to-peak single-ended swing across this load.

The voltage at AREF is half the single-ended peak-to-peak

value of the output signal (or −100 mV in this case).

No adjustments are necessary with DC coupling.

If the outputs are AC coupled, however, the voltage at

AREF is half the single-ended peak-to-peak value of the

output signal multiplied by a factor R-----L--R--+---L--R-----o

where R L is the external load and Ro is the output

impedance of the TZA3004HL.

To maintain a 200 mV peak-to-peak single-ended swing

across a 50 Ω AC coupled load, the voltage at AREF must

be –----1---0---0------m-----V-----×-----5-(--0-5---0--Ω----Ω------+-----1---0---0------Ω----)-- = –300 mV .

This can be achieved by connecting a 7.3 kΩ resistor

between AREF and VEE.

The formulae for calculating the required voltage at AREF

and the external resistance needed between AREF and

VEE when the outputs are AC coupled are:

VAREF = –R-----L--R--+---L--R-----o × 12-- Vswing

(1)

and:

R

1

×







V----V-A---ER---E-E---F-

–



1



RAREF

=

----------------------------------------------------------------

1

–







RR-----12--

×







V----V-A---ER---E-E---F-

–



1









(2)

where R1 = 500 Ω, R2 = 16 kΩ and VEE = −3.3 V. RAREF

is connected between AREF and VEE.

1998 Feb 09

7

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