ICS84330C Datasheet, PDF (14/19 Pages) Integrated Circuit Systems – 700MHZ, LOW JITTER, CRYSTAL-TO-3.3V DIFFERENTIAL LVPECL FREQUENCY SYNTHESIZER

Integrated
Circuit
Systems, Inc.
ICS84330C
700MHZ, LOW JITTER, CRYSTAL-TO-3.3V
DIFFERENTIAL LVPECL FREQUENCY SYNTHESIZER
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 the Figure 8.
V
CC
Q1
V_OUT
RL
50
V_CC - 2V
FIGURE 8. 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.
CC
• For logic high, V = V
=V
– 1.0V
OUT
OH_MAX
CC_MAX
(V
- V ⁾ = 1.0V
CC_MAX OH_MAX
• For logic low, V = V = V – 1.7V
OUT
OL_MAX
CC_MAX
(V
- V ⁾ = 1.7V
CC_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
CC_MAX
L
CC_MAX OH_MAX
CC_MAX
OH_MAX
L
CC_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
CC_MAX
L
CC_MAX OL_MAX
CC_MAX
OL_MAX
L
CC_MAX OL_MAX
[(2V - 1.7V)/50Ω] * 1.7V = 10.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30.2mW
84330CV
www.icst.com/products/hiperclocks.html
14
REV. B DECEMBER 7, 2004