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843N001I Datasheet, PDF (15/20 Pages) Integrated Device Technology – Low Voltage, LVCMOS/LVPECL-to-LVPECL/ECL Clock Generator | |||
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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 7
873991-147 DATA SHEET
FIGURE 7. 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 â 2V.
CCO
â¢
For
logic
high,
VOUT
=
V
OH_MAX
=
V
CCO_MAX
â
0.9V
(VCCO_MAX â V ) OH_MAX = 0.9V
⢠For logic low, VOUT = VOL_MAX = V â CCO_MAX 1.7V
(V â V ) = 1.7V
CCO_MAX
OL_MAX
Pd_H is power dissipation when the output drives high.
Pd_L is the power dissipation when the output drives low.
Pd_H = [(V â (V â 2V))/R ] * (V â V ) = [(2V â (V â V ))/R ] * (V â V ) =
OH_MAX
CCO_MAX
L
CCO_MAX
OH_MAX
CCO_MAX
OH_MAX
L
CCO_MAX
OH_MAX
[(2V â 0.9V)/50Ω] * 0.9V = 19.8mW
Pd_L = [(V â (V â 2V))/R ] * (V â V ) = [(2V â (V â V ))/R ] * (V â V ) =
OL_MAX
CCO_MAX
L
CCO_MAX
OL_MAX
CCO_MAX
OL_MAX
L
CCO_MAX
OL_MAX
[(2V â 1.7V)/50Ω] * 1.7V = 10.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30mW
REVISION B 8/25/15
15
LOW VOLTAGE, LVCMOS/LVPECL-TO LVPECL/ECL
CLOCK GENERATOR
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