ICS87322BYIT IDT, Integrated Device Technology Inc, ICS87322BYIT Datasheet - Page 10

• Manufacturer Part Number: ICS87322BYIT
• Manufacturer: IDT, Integrated Device Technology Inc
• Type: Clock Dividerr

Specifications of ICS87322BYIT

• Number Of Clock Inputs: 2
• Mode Of Operation: Differential
• Output Frequency: 750MHz
• Output Logic Level: ECL/LVPECL
• Operating Supply Voltage (min): -3/3V
• Operating Supply Voltage (typ): -3.3/3.3V
• Operating Supply Voltage (max): -3.8/3.8V
• Package Type: LQFP
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Signal Type: CML/LVDS/LVPECL/SSTL
• Mounting: Surface Mount
• Pin Count: 52
• Lead Free Status / RoHS Status: Not Compliant

This section provides information on power dissipation and junction temperature for the ICS87322BI.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS87322BI 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 the devices is 125°C.
In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance θ
moderate air flow of 200 linear feet per minute and a multi-layer board, the appropriate value is 36.4°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
87322BYI
ABLE
•
•
6. T
Single-Layer PCB, JEDEC Standard Test Boards
Multi-Layer PCB, JEDEC Standard Test Boards
NOTE: Most modern PCB designs use multi-layered boards. The data in the second row pertains to most designs.
Power (core)
Power (outputs)
If all outputs are loaded, the total power is 15 * 30mW = 450mW
Total 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
85°C + 1.058W * 36.4°C/W = 123.5°C. This is below the limit of 125°C.
JA
A
= Ambient Temperature
= Junction-to-Ambient Thermal Resistance
HERMAL
R
MAX
ESISTANCE
_MAX
MAX
= V
(3.8V, with all outputs switching) = 608mW + 450mW = 1058mW
= 30mW/Loaded Output pair
CC_MAX
θ θ θ θ θ
* I
JA
EE_MAX
FOR
θ θ θ θ θ
JA
P
CC
52-
= 3.8V * 160mA = 608mW
by Velocity (Linear Feet per Minute)
= 3.8V, which gives worst case results.
OWER
PIN
JA
* Pd_total + T
LQFP, F
C
www.idt.com
ONSIDERATIONS
ORCED
A
10
C
58.0°C/W
42.3°C/W
ONVECTION
3.3V LVPECL/ECL C
0
47.1°C/W
36.4°C/W
200
JA
must be used. Assuming a
L
ICS87322BI
OW
LOCK
42.0°C/W
34.0°C/W
S
500
REV. C OCTOBER 13, 2010
KEW
G
ENERATOR
, ÷1/÷2,