ICS853S057I Datasheet, PDF (12/16 Pages) Integrated Device Technology – Maximum input/output frequency

ICS853S057I Data Sheet
4:1, DIFFERENTIAL-TO-3.3V, 2.5V LVPECL/ECL CLOCK DATA MULTIPLEXER
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 5.
V_CC
Q1
V_OUT
RL
50Ω
V_CC - 2V
Figure 5. LVPECL Driver Circuit and Termination
To calculate worst case power dissipation into the load, use the following equations which assume a 50Ω 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 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}) = [(2V – (V_{CC_MAX} – V_{OH_MAX}))/R_L] * (V_{CC_MAX} – V_{OH_MAX}) =
[(2V – 0.935V)/50Ω] * 0.935V = 19.9mW
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)/50Ω] * 1.67V = 11.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 31.1mW
ICS853S057AGI REVISION A MAY 16, 2012
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©2012 Integrated Device Technology, Inc.