ICS85310I-21 Datasheet, PDF (11/15 Pages) Integrated Circuit Systems – LOW SKEW, DUAL, 1-TO-5 DIFFERENTIAL-TO-2.5V/3.3V ECL/LVPECL FANOUT BUFFER

Integrated
Circuit
Systems, Inc.
ICS85310I-21
LOW SKEW, DUAL, 1-TO-5
DIFFERENTIAL-TO-2.5V/3.3V ECL/LVPECL FANOUT BUFFER
3. Calculations and Equations.
LVPECL output driver circuit and termination are shown in Figure 5.
V_CCO
Q1
V_OUT
RL
50
V_CCO - 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
– 1.0V
OUT
OH_MAX
CCO_MAX
(V
- V ⁾ = 1.0V
CCO_MAX OH_MAX
• For logic low, V = V = V
– 1.7V
OUT
OL_MAX
CCO_MAX
(V
- V ⁾ = 1.7V
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 - 1V)/50Ω] * 1V = 20.0mW
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 - 1.7V)/50Ω] * 1.7V = 10.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30.2mW
85310AYI-21
www.icst.com/products/hiperclocks.html
11
REV. D JUNE 30, 2005