ICS85357-01 Просмотр технического описания (PDF) - Integrated Circuit Systems

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ICS85357-01

4:1 OR 2:1 DIFFERENTIAL-TO-3.3V LVPECL / ECL CLOCK MULTIPLEXER

Integrated Circuit Systems 

Integrated

Circuit

Systems, Inc.

ICS85357-01

4:1 OR 2:1

DIFFERENTIAL-TO-3.3V LVPECL / ECL CLOCK MULTIPLEXER

3. Calculations and Equations.

LVPECL output driver circuit and termination are shown in Figure 4.

V

CC

Q1

VOUT

RL

50

VCC - 2V

FIGURE 4. LVPECL DRIVER CIRCUIT AND TERMINATION

To calculate worst case power dissipation into the load, use the following equations which assume a 50Ω load, and a termination

voltage of V - 2V.

CC

• For logic high, V = V

=V

– 1.0V

OUT

OH_MAX

CC_MAX

(V

- V ) = 1.0V

CC_MAX OH_MAX

• For logic low, V = V = V – 1.7V

OUT

OL_MAX

CC_MAX

(V

- V ) = 1.7V

CC_MAX OL_MAX

Pd_H is power dissipation when the output drives high.

Pd_L is the power dissipation when the output drives low.

Pd_H = [(V

– (V - 2V))/R ] * (V - V ) = [(2V - (V

- V ))/R ] * (V - V ) =

OH_MAX

CC_MAX

L

CC_MAX OH_MAX

CC_MAX OH_MAX

L

CC_MAX OH_MAX

[(2V - 1V)/50Ω] * 1V = 20.0mW

Pd_L = [(V – (V - 2V))/R ] * (V

- V ) = [(2V - (V

- V ))/R ] * (V - V ) =

OL_MAX

CC_MAX

L

CC_MAX OL_MAX

CC_MAX OL_MAX

L

CC_MAX OL_MAX

[(2V - 1.7V)/50Ω] * 1.7V = 10.2mW

Total Power Dissipation per output pair = Pd_H + Pd_L = 30.2mW

85357AG-01

www.icst.com/products/hiperclocks.html

9

REV. A MARCH 21, 2005

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