
ICS8430S07AKI REVISION A SEPTEMBER 3, 2009
19
2009 Integrated Device Technology, Inc.
ICS8430S07I Data Sheet
CLOCK GENERATOR FOR CAVIUM PROCESSORS
Power Considerations
This section provides information on power dissipation and junction temperature for the ICS8430S07I.
Equations and example calculations are also provided.
1.
Power Dissipation.
The total power dissipation for the ICS8430S07I is the sum of the core power plus the analog power plus the power dissipated in the load(s).
The following is the power dissipation for VDD = 3.3V + 5% = 3.465V, which gives worst case results.
Core and LVPECL Output Power Dissipation
Power (core)_MAX = VDD_MAX * (IEE_MAX + IDDA + IDDO) = 3.465V * (170mA + 20mA + 25mA) = 744.98mW
Power (output)_MAX = 30mW/Loaded Output Pair
LVCMOS Output Power Dissipation
Output Impedance ROUT Power Dissipation due to Loading 50 to VDDO/2
Output Current IOUT = VDDO_MAX / [2 * (50 + ROUT)] = 3.465V / [2 * (50 + 15)] = 26.7mA
Power Dissipation on the ROUT per LVCMOS output
Power (ROUT) = ROUT * (IOUT)
2 = 15
* (26.7mA)2 = 10.7mW per output
Total Power Dissipation on the ROUT
Total Power (ROUT) = 10.7mW * 6 = 64.2mW
Dynamic Power Dissipation at 25MHz
Power (25MHz) = CPD * Frequency * (VDDO)
2 = 4pF * 25MHz * (3.465V)2 = 1.5mW per output
Total Power (25MHz) = 1.5mW * 3 = 4.5mW
Dynamic Power Dissipation at 133MHz
Power (133MHz) = CPD * Frequency * (VDDO)
2 = 4pF * 133MHz * (3.465V)2 = 8mW per output
Total Power (133MHz) = 8mW * 3 = 24mW
Total Power Dissipation
Total Power
= Power (core) + Power (LVPECL output) + Total Power (ROUT) + Total Power (25MHz) + Total Power (125MHz)
= 745mW + 30mW + 64.2mW + 4.5mW + 24mW
= 867.7mW