8SLVP1204 DATA SHEET
LOW PHASE NOISE, 2:4, 3.3V, 2.5V LVPECL OUTPUT
FANOUT BUFFER
20 REVISION D 6/8/15
Case Temperature Considerations
This device supports applications in a natural convection environment which does not have any thermal conductivity through ambient air. The
printed circuit board (PCB) is typically in a sealed enclosure without any natural or forced air flow and is kept at or below a specific temperature.
The device package design incorporates an exposed pad (ePad) with enhanced thermal parameters which is soldered to the PCB where most
of the heat escapes from the bottom exposed pad. For this type of application, it is recommended to use the junction-to-board thermal
characterization parameter
JB
(Psi-JB) to calculate the junction temperature (T
J
) and ensure it does not exceed the maximum allowed junction
temperature in the Absolute Maximum Rating table.
The junction-to-board thermal characterization parameter,
JB
, is calculated using the following equation:
T
J
= T
CB
+
JB
x P
d
, Where
T
J
= Junction temperature at steady state condition in (
o
C).
T
CB
= Case temperature (Bottom) at steady state condition in (
o
C).
JB
=
Thermal characterization parameter to report the difference between junction temperature and the temperature of the board
measured at the top surface of the board.
P
d
= power dissipation (W) in desired operating configuration.
The ePad provides a low thermal resistance path for heat transfer to the PCB and represents the key pathway to transfer heat away from the
IC to the PCB. It’s critical that the connection of the exposed pad to the PCB is properly constructed to maintain the desired IC case temperature
(T
CB
). A good connection ensures that temperature at the exposed pad (T
CB
) and the board temperature (T
B
) are relatively the same. An
improper connection can lead to increased junction temperature, increased power consumption and decreased electrical performance. In
addition, there could be long-term reliability issues and increased failure rate.
Example Calculation for Junction Temperature (T
J
): T
J
= T
CB
+
JB
x P
d
For the variables above, the junction temperature is equal to 107
o
C. Since this is below the maximum junction temperature of 125
o
C, there are
no long term reliability concerns. In addition, since the junction temperature at which the device was characterized using forced convection is
111.2
o
C, this device can function without the degradation of the specified AC or DC parameters.
Package type: 16-Lead VFQFN
Body size: 3mm x 3mm x0.9mm
ePad size: 1.7mm x 1.7mm
Thermal Via: 2 x 2 matrix
JB
5.1 C/W
T
CB
105
o
C
P
d
0.351 W
T
J
T
CB
