8535AGI-31LFT IDT, 8535AGI-31LFT Datasheet - Page 10

• Manufacturer Part Number: 8535AGI-31LFT
• Description: Clock Drivers & Distribution 1
• Manufacturer: IDT

Specifications of 8535AGI-31LFT

• Rohs: yes
• Part # Aliases: ICS8535AGI-31LFT

ICS8535I-31
Power Considerations
This section provides information on power dissipation and junction temperature for the ICS8535I-31.
Equations and example calculations are also provided.
1.
The total power dissipation for the ICS8535I-31 is the sum of the core power plus the 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.
Total Power
2. Junction Temperature.
Junction temperature, Tj, is the temperature at the junction of the bond wire and bond pad directly affects the reliability of the device. The
maximum recommended junction temperature is 125°C. Limiting the internal transistor junction temperature, Tj, to 125°C ensures that the bond
wire and bond pad temperature remains below 125°C.
In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance θ
flow of 200 linear feet per meter and a multi-layer board, the appropriate value is 66.6°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 (multi-layer).
Table 7. Thermal Resistance
ICS8535AGI-31 REVISION A JANUARY 27, 2010
Linear Feet per minute
Multi-Layer PCB, JEDEC Standard Test Boards
Power Dissipation.
•
•
85°C + 0.345W * 66.6°C/W = 108°C. This is below the limit of 125°C.
Power (core)
Power (outputs)
If all outputs are loaded, the total power is 4 * 30mW = 120mW
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
JA
A
= Ambient Temperature
_MAX
= Junction-to-Ambient Thermal Resistance
(3.465V, with all outputs switching) = 225.2mW + 120mW = 345.2mW
MAX
MAX
= V
= 30mW/Loaded Output Pair
CC_MAX
θ
JA
* I
for 20 Lead TSSOP, Forced Convection
EE_MAX
CC
= 3.3V + 5% = 3.465V, which gives worst case results.
JA
= 3.465V * 65mA = 225.2mW
* Pd_total + T
θ
JA
73.2°C/W
LOW SKEW, 1-TO-4, CRYSTAL OSCILLATOR/LVCMOS-TO-3.3V LVPECL FANOUT BUFFER
A
by Velocity
0
10
66.6°C/W
200
JA
must be used. Assuming a moderate air
©2010 Integrated Device Technology, Inc.
63.5°C/W
500