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ICS853052AG REV. B OCTOBER 24, 2007

ICS853052

DUAL LVCMOS/LVTTL-TO-DIFFERENTIAL 2.5V, 3.3V, 5V LVPECL MULTIPLEXER

PRELIMINARY

3. Calculations and Equations.

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

Ω load, and a

termination voltage of V

CC

- 2V.

•

For logic high, V

OUT

= V

OH_MAX

= V

CC_MAX

– 0.935V

(V

CC_MAX

- V

OH_MAX

) = 0.935V

•

For logic low, V

OUT

= V

OL_MAX

= V

CC_MAX

– 1.67V

(V

CC_MAX

- V

OL_MAX

) = 1.67V

Pd_H = [(V

OH_MAX

– (V

CC_MAX

- 2V))/R

L

] * (V

CC_MAX

- V

OH_MAX

) = [(2V - (V

CC_MAX

- V

OH_MAX

))/R

L

] * (V

CC _MAX

- V

OH_MAX

) =

[(2V - 0.935V)/50

Ω] * 0.935V = 19.92mW

Pd_L = [(V

OL_MAX

– (V

CC_MAX

- 2V))/R

L

] * (V

CC_MAX

- V

OL_MAX

) = [(2V - (V

CC_MAX

- V

OL_MAX

))/R

L

] * (V

CC_MAX

- V

OL_MAX

) =

[(2V - 1.67V)/50

Ω] * 1.67V = 11.02mW

Total Power Dissipation per output pair = Pd_H + Pd_L = 30.94mW

Figure 4. LVPECL Driver Circuit and Termination

VOUT

Q1

VCC - 2V

RL

50

VCC