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ICS853111B Datasheet, PDF (14/19 Pages) Integrated Circuit Systems – LOW SKEW, 1-TO-10 DIFFERENTIAL-TO-2.5V/3.3V LVPECL/ECL FANOUT BUFFER
ICS853111B
LOW SKEW, 1-TO-10, DIFFERENTIAL-TO-2.5V, 3.3V LVPECL/ECL FANOUT BUFFER
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.
VCCO
Q1
VOUT
RL
50
VCCO - 2V
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 - 2V.
CCO
• For logic high, V = V = V – 0.935V
OUT
OH_MAX
CCO_MAX
(V - V ) = 0.935V
CC_MAX
OH_MAX
• For logic low, V = V = V – 1.67V
OUT
OL_MAX
CCO_MAX
(V - V ) = 1.67V
CCO_MAX
OL_MAX
Pd_H = [(V – (V - 2V))/R ] * (V - V ) = [(2V - (V
- V ))/R ] * (V - V ) =
OH_MAX
CCO_MAX
L
CCO_MAX
OH_MAX
CCO_MAX
OH_MAX
L
CCO _MAX
OH_MAX
[(2V - 0.935V)/50Ω] * 0.935V = 19.92mW
Pd_L = [(V – (V - 2V))/R ] * (V - V ) = [(2V - (V
- V ))/R ] * (V - V ) =
OL_MAX
CCO_MAX
L
CCO_MAX
OL_MAX
CCO_MAX
OL_MAX
L
CCO_MAX
OL_MAX
[(2V - 1.67V)/50Ω] * 1.67V = 11.02mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30.94mW
IDT™ / ICS™ 1-TO-10, LVPECL/ECL FANOUT BUFFER
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ICS853111BY REV. B SEPTEMBER 5, 2007