85104AGILFT Integrated Device Technology (Idt), 85104AGILFT Datasheet - Page 12

• Manufacturer Part Number: 85104AGILFT
• Description: Clock Driver 2-IN HCSL 20-Pin TSSOP T/R
• Manufacturer: Integrated Device Technology (Idt)

Specifications of 85104AGILFT

• Package: 20TSSOP
• Configuration: 1 x 2:1
• Input Signal Type: HCSL|LVCMOS|LVDS|LVHSTL|LVPECL|LVTTL|SSTL
• Maximum Output Frequency: 500 MHz
• Operating Supply Voltage: 3.3 V

This section provides information on power dissipation and junction temperature for the ICS85104I.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS85104I 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 HiPerClockS
In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance
flow and a multi-layer board, the appropriate value is 91.1°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).
T
IDT
ABLE
ICS85104I
LOW SKEW, 1-TO-4, DIFFERENTIAL/LVCMOS-TO-0.7V HCSL FANOUT BUFFER
™
/ ICS
6. T
Multi-Layer PCB, JEDEC Standard Test Boards
Power (core)
Power (outputs)
If all outputs are loaded, the total power is 4 * 47.3mW = 189.2mW
Total Power
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
85°C + 0.287W * 91.1°C/W = 111.1°C. This is well below the limit of 125°C.
™
JA
A
0.7V HCSL FANOUT BUFFER
HERMAL
= Ambient Temperature
= Junction-to-Ambient Thermal Resistance
R
ESISTANCE
MAX
_MAX
= V
MAX
(3.63V, with all outputs switching) = 98.01mW + 189.2mW = 287.21mW
= 47.3mW/Loaded Output pair
DD_MAX
JA
* I
FOR
DD_MAX
20-L
= 3.63V * 27mA = 98.01mW
DD
EADN
= 3.3V + 10% = 3.63V, which gives worst case results.
P
JA
by Velocity (Meters per Second)
OWER
JA
* Pd_total + T
TSSOP, F
C
ORCED
ONSIDERATIONS
A
12
91.1°C/W
C
0
ONVECTION
TM
devices is 125°C.
86.7°C/W
1
ICS85104AGI REV. A FEBRUARY 25, 2009
JA
must be used. Assuming no air
84.6°C/W
2.5