ICS85222-02 Datasheet, PDF (7/12 Pages) Integrated Circuit Systems – 1-TO-2 LVCMOS / LVTTL-TO DIFFERENTIAL HSTL TRANSLATOR

ICS85222-02
1-TO-2, LVCMOS/LVTTL-TO-DIFFERENTIAL HSTL TRANSLATOR
3. Calculations and Equations.
The purpose of this section is to derive the power dissipated into the load.
HSTL output driver circuit and termination are shown in Figure 1.
V
DD
Q1
V_OUT
RL
50Ω
FIGURE 1. HSTL DRIVER CIRCUIT AND TERMINATION
To calculate worst case power dissipation into the load, use the following equations which assume a 50Ω load.
Pd_H is power dissipation when the output drives high.
Pd_L is the power dissipation when the output drives low.
Pd_H = (V /R ) * (V - V )
OH_MAX L
DD_MAX
OH_MAX
Pd_L = (V /R ) * (V - V )
OL_MAX L
DD_MAX
OL_MAX
Pd_H = (1.4V/50Ω) * (3.465V - 1.4V) = 57.8mW
Pd_L = (0.4V/50Ω) * (3.465V - 0.4V) = 24.52mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 82.3mW
IDT^™ / ICS^™ DIFFERENTIAL HSTL TRANSLATOR
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ICS85222AM-02 REV. B SEPTEMBER 12, 2007