Integrated

Circuit

Systems, Inc.

ICS8521

8521BY

www.icst.com/products/hiperclocks.html

REV. B JULY 31, 2001

10

3. Calculations and Equations.

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

LVHSTL output driver circuit and termination are shown in

Figure 10.

Ω load, and a termination

voltage of V

DD

- 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

/R

L

) * (V

DD_MAX

- V

OH_MAX

)

Pd_L = (V

OL_MAX

/R

L

) * (V

DD_MAX

- V

OL_MAX

)

•

For logic high, V

OUT

= V

OH_MAX

= V

DD_MAX

– 1.2V

•

For logic low, V

OUT

= V

OL_MAX

= V

DD_MAX

– 0.4V

Pd_H = (1.2V/50

Ω) * (2V - 1.2V) = 19.2mW

Pd_L = (0.4V/50

Ω) * (2V - 0.4V) = 12.8mW

Total Power Dissipation per output pair = Pd_H + Pd_L = 32mW

V

DD

V

OUT

RL

50

Ω

Q1