85214AGLF IDT, Integrated Device Technology Inc, 85214AGLF Datasheet - Page 10

• Manufacturer Part Number: 85214AGLF
• Manufacturer: IDT, Integrated Device Technology Inc
• Type: Clock Driverr

Specifications of 85214AGLF

• Number Of Clock Inputs: 2
• Output Frequency: 700MHz
• Output Logic Level: HSTL
• Operating Supply Voltage (min): 3.135V
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (max): 3.465V
• Package Type: TSSOP
• Operating Temp Range: 0C to 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 20
• Lead Free Status / RoHS Status: Compliant

Power Considerations
This section provides information on power dissipation and junction temperature for the ICS85214.
Equations and example calculations are also provided.
1.
The total power dissipation for the ICS85214 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.
Total Power_
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
air flow of 200 linear feet per minute and a multi-layer board, the appropriate value is 66.6°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™ HSTL FANOUT BUFFER
Linear Feet per Minute
Single-Layer PCB, JEDEC Standard Test Boards
Multi-Layer PCB, JEDEC Standard Test Boards
ICS85214
LOW SKEW, 1-TO-5, DIFFERENTIAL-TO-HSTL FANOUT BUFFER
Power Dissipation.
•
•
Power (core)
Power (outputs)
If all outputs are loaded, the total power is 5 x 32.8mW = 164mW
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 + 0.391W * 66.6°C/W = 111°C. This is well below the limit of 125°C.
JA
A
= Ambient Temperature
= Junction-to-Ambient Thermal Resistance
MAX
(3.465V, with all outputs switching) = 227.2mW + 144mW = 391.2mW
MAX
MAX
= V
= 32.8mW/Loaded Output pair
DD_MAX
θ
JA
for 20 Lead TSSOP, Forced Convection
* I
DD_MAX
DD
= 3.3V + 5% = 3.465V, which gives worst case results.
JA
= 3.465V * 850mA = 227.2mW
* Pd_total + T
θ
114.5°C/W
JA
73.2°C/W
A
by Velocity
0
10
98.0°C/W
66.6°C/W
200
JA
ICS85214AG REV. B FEBRUARY 25, 2008
must be used. Assuming a moderate
88.0°C/W
63.5°C/W
500