8T49N241 Datasheet, PDF (56/64 Pages) Integrated Circuit Systems – Manual clock selection control input

8T49N241 DATA SHEET
Table 15I. 1.8V LVCMOS Output Calculation Table
Output
Base_Current (mA)
Q0
22.8
Q1
Q2
33.1
Q3
Applying the values to the following equation will yield output current by frequency:
Qx Current (mA) = FQ_Factor * Frequency (MHz) + Base_Current
where:
Qx Current is the specific output current according to output type and frequency
FQ_Factor is used for calculating current increase due to output frequency
Base_Current is the base current for each output path independent of output frequency
The second step is to multiply the power dissipated by the thermal impedance to determine the maximum power gradient, using the following
equation:
T_J = T_A + (_JA * Pd_total)
where:
T_J is the junction temperature (°C)
T_A is the ambient temperature (°C)
_JA is the thermal resistance value from Table 14, dependent on ambient airflow (°C/W)
Pd_total is the total power dissipation of the 8T49N241 under usage conditions, including power dissipated due to loading (W).
Note that the power dissipation per output pair due to loading is assumed to be 27.95mW for LVPECL outputs and 44.5mW for HCSL outputs.
When selecting LVCMOS outputs, power dissipation through the load will vary based on a variety of factors including termination type and trace
length. For these examples, power dissipation through loading will be calculated using C_PD (found in Table 2) and output frequency:
Pd_OUT = C_PD * F_OUT * V_CCO2
where:
Pd_OUT is the power dissipation of the output (W)
C_PD is the power dissipation capacitance (pF)
F_OUT is the output frequency of the selected output (MHz)
V_CCO is the voltage supplied to the appropriate output (V)
FEMTOCLOCK^®NG UNIVERSAL FREQUENCY TRANSLATOR
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REVISION 1 08/07/15