ICS85304AG-01 Ver la hoja de datos (PDF) - Integrated Circuit Systems
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ICS85304AG-01 Datasheet PDF : 13 Pages
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Integrated
Circuit
Systems, Inc.
ICS85304-01
LOW SKEW, 1-TO-5
DIFFERENTIAL-TO-3.3V LVPECL FANOUT BUFFER
3. Calculations and Equations.
LVPECL output driver circuit and termination are shown in Figure 9.
VCC
Q1
VOUT
RL
50
VCC - 2V
FIGURE 9 - 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
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
)
OH_MAX
CC
L
CC OH_MAX
Pd_L = [(V
(V - 2V))/R ]*(V - V
)
OL_MAX
CC
L
CC OL_MAX
• For logic high , V = V
= V 1.0V
OUT
OH_MAX
CC
Using V = 3.465, this results in V
= 2.465V
CC
OH_MAX
• For logic low , V = V
= V 1.7V
OUT
OL_MAX
CC
Using V = 3.465, this results in V
= 1.765V
CC
OL_MAX
Pd_H = [(2.465V - (3.465V - 2V))/50 Ω]*(3.465V - 2.465V) = 20.0mW
Pd_L = [(1.765V - (3.465V - 2V))/50 Ω]*(3.465V - 1.765V) = 10.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30.2mW
85304AG-01
www.icst.com/products/hiperclocks.html
10
REV. B JULY 13, 2001
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