ICS8530DY-01

www.icst.com/products/hiperclocks.html

REV. B AUGUST 8, 2001

9

Integrated

Circuit

Systems, Inc.

ICS8530-01

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