852911AVILF IDT, 852911AVILF Datasheet - Page 10

• Manufacturer Part Number: 852911AVILF
• Description: Clock Drivers & Distribution
• Manufacturer: IDT

Specifications of 852911AVILF

• Product Category: Clock Drivers & Distribution
• Rohs: yes
• Part # Aliases: ICS852911AVILF

This section provides information on power dissipation and junction temperature for the ICS852911I.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS852911I 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 the devices is 125°C.
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 31.1°C/W per Table 6 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).
Table 6. Thermal Resistance θ θ θ θ θ
852911AVI
•
•
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 9 * 87.2mW = 784.8mW
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
85°C + 1.127W * 31.1°C/W = 120°C. This is below the limit of 125°C.
JA
A
= Ambient Temperature
= junction-to-ambient thermal resistance
MAX
_MAX
MAX
= V
(3.6V, with all outputs switching) = 342mW + 784.8mW = 1126.8mW
= 87.2mW/Loaded Output pair
DD_MAX
* I
JA
DD_MAX
θ θ θ θ θ
for 28-pin PLCC, Forced Convection
JA
P
DD
by Velocity (Linear Feet per Minute)
= 3.6V * 95mA = 342mW
= 3.3V + 0.3V = 3.6V, which gives worst case results.
OWER
JA
* Pd_total + T
C
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ONSIDERATIONS
A
10
37.8°C/W
0
D
IFFERENTIAL
31.1°C/W
200
-
TO
-HSTL F
JA
must be used. Assuming a
L
ICS852911I
28.3°C/W
OW
500
ANOUT
S
KEW
REV. A AUGUST 5, 2010
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UFFER
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