8701CY

www.icst.com/products/hiperclocks.html

REV. B AUGUST 2, 2001

12

Integrated

Circuit

Systems, Inc.

ICS8701

÷1, ÷2

3. Calculations and Equations.

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

LVCMOS output driver circuit and termination are shown in

Figure 7.

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

DDO

V

OUT

RL

50

Ω

Q1