ICS8530DY

www.icst.com/products/hiperclocks.html

REV. C AUGUST 7, 2001

9

Integrated

Circuit

Systems, Inc.

ICS8530

3. Calculations and Equations.

The purpose of this section is to derive the power dissipated into the load.

LVPECL output driver circuit and termination are shown in

Figure 9.

Ω load, and a termination

voltage of V

CC

- 2V.

Pd_H is power dissipation when the output drives high.

Pd_L is the power dissipation when the output drives low.

Pd_H = [(V

OH_MAX

– (V

CC_MAX

- 2V))/R

L

]*(V

CC_MAX

- V

OH_MAX

)

Pd_L = [(V

OL_MAX

– (V

CC_MAX

- 2V))/R

L

]*(V

CC_MAX

- V

OL_MAX

)

•

For logic high, V

OUT

= V

OH_MAX

= V

CC_MAX

– 1.0V

Using V

CC_MAX

= 2.625, this results in V

OH_MAX

= 1.625V

•

For logic low, V

OUT

= V

OL_MAX

= V

CC_MAX

– 1.7V

Using V

CC_MAX

= 2.625, this results in V

OL_MAX

= 0.925V

Pd_H = [(1.625V - (2.625V - 2V))/50

Ω]*(1V) = 20mW

Pd_L = [(0.925V - (2.625V - 2V))/50

Ω]*(1.7) = 10.2mW

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

Q1

V

OUT

V

CCO

RL

50

V