ics8430-111 Integrated Device Technology, ics8430-111 Datasheet - Page 13

• Manufacturer Part Number: ics8430-111
• Description: Programmable Low-jitter Lvpecl Or Lvcmos-input Lvpecl-output 2-output 700-mhz Clock Synthesizer
• Manufacturer: Integrated Device Technology

This section provides information on power dissipation and junction temperature for the ICS8430-111.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS8430-111 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 θ
moderate air flow of 200 linear feet per minute and a multi-layer board, the appropriate value is 42.1°C/W per Table 7 below.
Therefore, Tj for an ambient temperature of 70°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
ICS8430-111
700MHZ, LOW JITTER, DIFFERENTIAL-TO-3.3V LVPECL FREQUENCY SYNTHESIZER
™
•
•
The equation for Tj is as follows: Tj = θ
Tj = Junction Temperature
θ
Pd_total = Total Device Power Dissipation (example calculation is in section 1 above)
T
70°C + 0.476W * 42.1°C/W = 90°C. This is well below the limit of 125°C.
/ ICS
JA
A
7. T
= Ambient Temperature
= Junction-to-Ambient Thermal Resistance
Single-Layer PCB, JEDEC Standard Test Boards
Multi-Layer PCB, JEDEC Standard Test Boards
NOTE: Most modern PCB designs use multi-layered boards. The data in the second row pertains to most designs.
Power (core)
Power (outputs)
If all outputs are loaded, the total power is 2 * 30mW = 60mW
Total Power
™
3.3V LVPECL FREQUENCY SYNTHESIZER
HERMAL
R
MAX
ESISTANCE
_MAX
= V
MAX
(3.465V, with all outputs switching) = 415.8mW + 60mW = 475.8mW
= 30mW/Loaded Output pair
CC_MAX
θ θ θ θ θ
* I
JA
EE_MAX
FOR
= 3.465V * 120mA = 415.8mW
32-
θ θ θ θ θ
CC
JA
JA
PIN
= 3.3V + 5% = 3.465V, which gives worst case results.
P
by Velocity (Linear Feet per Minute)
* Pd_total + T
LQFP, F
OWER
ORCED
C
A
ONSIDERATIONS
C
67.8°C/W
47.9°C/W
ONVECTION
13
0
TM
devices is 125°C.
55.9°C/W
42.1°C/W
200
ICS8430DY-111 REV. F JANUARY 29, 2007
50.1°C/W
39.4°C/W
JA
must be used. Assuming a
500
PRELIMINARY