ics85411 Integrated Device Technology, ics85411 Datasheet - Page 11

• Manufacturer Part Number: ics85411
• Description: The Idt85411 Is A Low Skew, High Performance 1-to-2 Differential-to-lvds Fanout Buffer And A Member Of The Hiperclocks? Family Of High Performance Clock Solutions From Idt. The Clk, Nclk Pair Can Accept Most Standard Differential Input Levels.the
• Manufacturer: Integrated Device Technology

T
IDT
This section provides information on power dissipation and junction temperature for the ICS85411.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS85411 is the sum of the core power plus the power dissipated in the load(s).
The following is the power dissipation for V
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 200 linear feet per minute and a multi-layer board, the appropriate value is 103.3°C/W per Table 5 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).
ABLE
ICS85411
LOW SKEW, 1-TO-2 DIFFERENTIAL-TO-LVDS FANOUT BUFFER
™
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
70°C + 0.182W * 103.3°C/W = 88.8°C. This is below the limit of 125°C.
/ ICS
JA
A
5. 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)
™
DIFFERENTIAL-TO-LVDS FANOUT BUFFER
HERMAL
R
ESISTANCE
MAX
= V
DD_MAX
* I
JA
DD_MAX
FOR
8-L
= 3.63V * 50mA = 181.5mW
JA
DD
JA
EAD
= 3.3V + 10% = 3.63V, which gives worst case results.
P
by Velocity (Linear Feet per Minute)
* Pd_total + T
OWER
SOIC, F
ORCED
C
A
ONSIDERATIONS
C
153.3°C/W
112.7°C/W
11
ONVECTION
0
TM
devices is 125°C.
128.5°C/W
103.3°C/W
200
ICS85411AM REV. C JANUARY 17, 2007
JA
115.5°C/W
must be used. Assuming a
97.1°C/W
500