ICS853111-01 Datasheet, PDF (11/15 Pages) Integrated Circuit Systems – LOW SKEW, 1-TO-9 DIFFERENTIAL-TO-3.3V LVPECL/ECL FANOUT BUFFER

Integrated
Circuit
Systems, Inc.
ICS853111-01
LOW SKEW, 1-TO-9
DIFFERENTIAL-TO-3.3V LVPECL/ECL FANOUT BUFFER
3. Calculations and Equations.
LVPECL output driver circuit and termination are shown in Figure 5.
VCCO
Q1
VOUT
RL
50
VCCO - 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 - 2V.
CCO
• For logic high, V = V = V
– 0.935V
OUT
OH_MAX
CCO_MAX
(V
- V ⁾ = 0.935V
CCO_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 is power dissipation when the output drives high.
Pd_L is the power dissipation when the output drives low.
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 = 11.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30.94mW
853111AV-01
www.icst.com/products/hiperclocks.html
11
REV. A APRIL 25, 2005