ics8624 Integrated Device Technology, ics8624 Datasheet - Page 11

• Manufacturer Part Number: ics8624
• Description: Differential-input Hstl-output 1 5 700-mhz Clock Zero-delay Buffer
• Manufacturer: Integrated Device Technology

This section provides information on power dissipation and junction temperature for the ICS8624.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS8624 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
8624BY
ABLE
•
•
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.
7. T
Power (core)
Power (outputs)
If all outputs are loaded, the total power is 5 * 32.8mW = 164mW
Total Power
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 + 0.580W * 42.1°C/W = 94.4°C. This is well below the limit of 125°C.
JA
A
HERMAL
= Ambient Temperature
= Junction-to-Ambient Thermal Resistance
Integrated
Circuit
Systems, Inc.
R
ESISTANCE
MAX
_MAX
MAX
= V
= 32.8mW/Loaded Output pair
(3.465V, with all outputs switching) = 416mW + 164mW = 580mW
DD_MAX
θ θ θ θ θ
JA
* I
FOR
DD_MAX
θ θ θ θ θ
JA
32-
P
DD
by Velocity (Linear Feet per Minute)
= 3.465V * 120mA = 416mW
PIN
= 3.3V + 5% = 3.465V, which gives worst case results.
www.icst.com/products/hiperclocks.html
OWER
JA
LQFP, F
* Pd_total + T
C
ORCED
ONSIDERATIONS
A
11
D
C
ONVECTION
IFFERENTIAL
67.8°C/W
47.9°C/W
0
TM
devices is 125°C.
-
TO
55.9°C/W
42.1°C/W
-HSTL Z
200
JA
must be used. Assuming a
ERO
L
OW
50.1°C/W
39.4°C/W
500
D
S
ICS8624
ELAY
KEW
REV. C JUNE 15, 2004
, 1-
B
UFFER
TO
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