ICS889474AKLFT IDT, Integrated Device Technology Inc, ICS889474AKLFT Datasheet - Page 11

• Manufacturer Part Number: ICS889474AKLFT
• Description: IC MUX 2:1 DIFF LVDS 24-VFQFPN
• Manufacturer: IDT, Integrated Device Technology Inc
• Series: HiPerClockS™r
• Type: Fanout Buffer (Distribution), Multiplexerr

Specifications of ICS889474AKLFT

• Number Of Circuits: 1
• Ratio - Input:output: 2:2
• Differential - Input:output: Yes/Yes
• Input: CML, LVDS, LVHSTL, LVPECL
• Output: LVDS
• Frequency - Max: 2GHz
• Voltage - Supply: 2.375 V ~ 2.625 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-VFQFN
• Frequency-max: 2GHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 889474AKLFT

This section provides information on power dissipation and junction temperature for the ICS889474.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS889474 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 θ
flow and a multi-layer board, the appropriate value is 49.5°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).
T
IDT
ABLE
ICS889474
2:1 LVDS MULTIPLEXER WITH 1:2 FANOUT AND INTERNAL TERMINATION
™
•
•
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 + 0.271W * 49.5°C/W = 98.4°C. This is well below the limit of 125°C.
/ ICS
JA
A
6. T
= Ambient Temperature
= Junction-to-Ambient Thermal Resistance
Power (core)
Power Dissipation at built-in terminations: Assume the input is driven by a 2.5V SSTL driver as shown in Figure 1E and
estimated approximately 1.75V drop across IN and nIN.
Total Power Dissipation for the two 50Ω built-in terminations is: (1.75V)
Input pair for both inputs is 2 * 30.6mW = 61.2mW
Total Power
™
Multi-Layer PCB, JEDEC Standard Test Boards
LVDS MULTIPLEXER
HERMAL
R
ESISTANCE
MAX
_MAX
= V
(2.625V, with all outputs switching) = 210mW + 61.2mW = 271.2mW
DD_MAX
θ θ θ θ θ
JA
* I
FOR
DD_MAX
24-
= 2.625V * 80mA = 210mW
θ θ θ θ θ
DD
PIN
JA
JA
= 2.625V, which gives worst case results.
P
* Pd_total + T
vs. 0 Velocity (Meters per Second)
VFQFN, F
OWER
ORCED
C
A
ONSIDERATIONS
C
11
ONVECTION
49.5°C/W
0
TM
devices is 125°C.
2
/ (50Ω + 50Ω) = 30.6mW
43.3°C/W
1
ICS889474AK REV. A October 22, 2008
JA
must be used. Assuming no air
38.8°C/W
2.5