ics843001agt Integrated Device Technology, ics843001agt Datasheet - Page 10

• Manufacturer Part Number: ics843001agt
• Description: Femto Clocks Crystal-to- 3.3v Lvpecl Clock Generator
• Manufacturer: Integrated Device Technology

This section provides information on power dissipation and junction temperature for the ICS843001.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS843001 is the sum of the core power plus the power dissipated in the load(s).
The following is the power dissipation for V
NOTE: Please refer to Section 3 for details on calculating power dissipated in the load.
2. Junction Temperature.
Junction temperature, Tj, is the temperature at the junction of the bond wire and bond pad and directly affects the reliability of the
device. The maximum recommended junction temperature for HiPerClockS
In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance
moderate air flow of 1 meter per second and a multi-layer board, the appropriate value is 90.5°C/W per Table 7 below.
Therefore, Tj for an ambient temperature of 85°C with all outputs switching is:
This calculation is only an example. Tj will obviously vary depending on the number of loaded outputs, supply voltage, air flow,
and the type of board (single layer or multi-layer).
T
IDT
ABLE
ICS843001
FEMTOCLOCKS™ CRYSTAL-TO-3.3V LVPECL CLOCK GENERATOR
™
/ ICS
7. T
Power (core)
Power (outputs)
Total Power
The equation for Tj is as follows: Tj =
Tj = Junction Temperature
Pd_total = Total Device Power Dissipation (example calculation is in section 1 above)
T
85°C + 0.352W * 90.5°C/W = 116.9°C. This is below the limit of 125°C.
™
JA
A
Multi-Layer PCB, JEDEC Standard Test Boards
3.3V LVPECL CLOCK GENERATOR
HERMAL
= Ambient Temperature
= Junction-to-Ambient Thermal Resistance
R
ESISTANCE
MAX
_MAX
= V
MAX
(3.465V, with all outputs switching) = 322.2mW + 30mW = 352.2mW
= 30mW/Loaded Output pair
CC_MAX
JA
* I
FOR
EE_MAX
8-
= 3.465V * 93mA = 322.2mW
PIN
CC
= 3.3V + 5% = 3.465V, which gives worst case results.
TSSOP, F
P
JA
by Velocity (Meters per Second)
OWER
JA
* Pd_total + T
ORCED
C
ONSIDERATIONS
C
A
ONVECTION
10
101.7°C/W
0
TM
devices is 125°C.
90.5°C/W
1
ICS843001AG REV B DECEMBER 6, 2006
JA
must be used. Assuming a
89.8°C/W
2.5