OQ2541HP/C3 データシートの表示（PDF） - Philips Electronics

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OQ2541HP/C3

SDH/SONET data and clock recovery unit STM1/4/16 OC3/12/48 GE

Philips Electronics 

Philips Semiconductors

SDH/SONET data and clock recovery unit

STM1/4/16 OC3/12/48 GE

Product specification

OQ2541HP; OQ2541U

DIN,

CREF

50 Ω

VEE

50 Ω

DINQ,

CREFQ

handbook, halfpage

100 Ω

100 Ω

DOUTQ, COUTQ

DOUT, COUT

MGL669

VEE

VAREF

MGL670

Fig.4 RF data and clock input circuit.

Fig.5 RF data and clock output circuit.

Power supply and power control loop

The OQ2541 contains an on-board voltage regulator.

An external power transistor is needed to deliver the

supply to this circuit. The required external circuit is

straightforward, and can be built using a few components.

A suitable circuit with a power supply of −4.5 V is illustrated

in Fig.6.

A different configuration could be used, as long as the

power supply rejection ratio is greater than 60 dB for all

frequencies. The inductor is a RF choke with an

impedance greater than 50 Ω at frequencies higher than

2 MHz. Any transistor with a β > 100 and enough current

sink capability can be used.

The OQ2541 can also be used with a power supply of

−5.0 or −5.2 V. The only adaptation to be made to the

power control circuit is to change the emitter resistor R1

(see Table 1).

Table 1 Value of resistor R1.

POWER SUPPLY

−4.5 V

−5.0 V

−5.2 V

RESISTOR R1

2.0 Ω

6.8 Ω

8.2 Ω

Output amplitude reference

The voltage swing at the CML compatible output stages

(pins DOUT, DOUTQ, COUT, COUTQ, DLOOP,

DLOOPQ, CLOOP and CLOOPQ) can be controlled by

adjusting the voltage on pin AREF (see Fig.7). An internal

voltage divider of 500 Ω and 16 kΩ connected between

ground and VEE initially fixes this level.

In most applications the outputs will be DC-coupled to a

load of 50 Ω. The output level regulation circuit will

maintain a 200 mV (p-p) single-ended swing across this

load. The voltage on pin AREF is half the single-ended

peak-to-peak value of the output signal (−100 mV).

No adjustments are necessary with DC-coupling.

If the outputs are AC-coupled, the voltage on pin 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 RL is the external load and Ro is the output

impedance of the OQ2541 (100 Ω).

1999 May 27

7

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