
IDT / ICS 3.3V, 2.5V LVPECL/ LVCMOS FANOUT BUFFER
13
ICS8536CGI-33 REV. B OCTOBER 27, 2008
ICS8536I-33
LOW SKEW, 1-TO-6, CRYSTAL OSCILLATOR/LVCMOS-TO-3.3V, 2.5V LVPECL/LVCMOS FANOUT BUFFER
POWER CONSIDERATIONS
This section provides information on power dissipation and junction temperature for the ICS8536I-33.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS8536I-33 is the sum of the core power plus the power dissipated in the load(s).
The following is the power dissipation for V
CC
= 3.3V + 5% = 3.465V, which gives worst case results.
NOTE: Please refer to Section 3 for details on calculating power dissipated in the load.
Core and LVPECL Output Power Dissipation
Power (core)
MAX
= V
CC_MAX
* I
EE_MAX
= 3.465V * 80mA = 277.2mW
Power (outputs)
MAX
= 30mW/Loaded Output pair
If all outputs are loaded, the total power is 3 * 30mW = 90mW
LVCMOS Output Power Dissipation
Output Impedance R
OUT
Power Dissipation due to Loading 50
Ω to V
CCO_LVCMOS
/2
Output Current I
OUT = VCCO_MAX / [2 * (50Ω + ROUT)] = 3.465V / [2 * (50Ω + 15Ω] = 26.7mA
Power Dissipation on the R
OUT per LVCMOS output
Power (R
OUT) = ROUT * (IOUT)
2
= 15
Ω * (26.7mA)2 = 10.7mW per output
Total Power Dissipation on the R
OUT
Total Power (R
OUT) = 10.7mW * 3 = 32.1mW
Total Power Dissipation
Total Power
= Power (LVPECL) + Total Power (R
OUT)
= 277.2mW + 90mW + 32.1mW
= 399.3mW