85401AKLFT IDT, Integrated Device Technology Inc, 85401AKLFT Datasheet - Page 10

• Manufacturer Part Number: 85401AKLFT
• Manufacturer: IDT, Integrated Device Technology Inc
• Type: Clock Multiplexerr

Specifications of 85401AKLFT

• Number Of Clock Inputs: 2
• Mode Of Operation: Differential
• Output Frequency: >2500MHz
• Output Logic Level: LVDS
• Operating Supply Voltage (min): 3.135V
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (max): 3.465V
• Package Type: VFQFN
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 16
• Lead Free Status / RoHS Status: Compliant

Power Considerations
This section provides information on power dissipation and junction temperature for the ICS85401.
Equations and example calculations are also provided.
1.
The total power dissipation for the ICS85401 is the sum of the core power plus the analog 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 devices is 125°C.
In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance θ
and a multi-layer board, the appropriate value is 51.5°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 Resitance
IDT™ / ICS™ LVDS MULTIPLEXER
Linear Feet per Minute
Multi-Layer PCB, JEDEC Standard Test Boards
ICS85401
2:1 DIFFERENTIAL-TO-LVDS MULTIPLEXER
Power Dissipation.
•
85°C + 0.139W * 51.5°C/W = 92.2°C. This iswell below the limit of 125°C.
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
JA
A
= Ambient Temperature
= Junction-to-Ambient Thermal Resistance
MAX
= V
DD_MAX
* I
θ
JA
DD_MAX
for 16 Lead VFQFN, Forced Convection
DD
= 3.465V * 40mA = 138.6mW
= 3.3V + 5% = 3.465V, which gives worst case results.
JA
* Pd_total + T
θ
JA
51.5°C/W
by Velocity
A
0
10
JA
must be used. Assuming no air flow
ICS85401AK REV. A MARCH 6, 2007