ICS85357AG-11T IDT, Integrated Device Technology Inc, ICS85357AG-11T Datasheet - Page 7

• Manufacturer Part Number: ICS85357AG-11T
• Manufacturer: IDT, Integrated Device Technology Inc
• Type: Clock Multiplexerr

Specifications of ICS85357AG-11T

• Number Of Clock Inputs: 4
• Mode Of Operation: Single-Ended
• Output Logic Level: ECL/LVPECL
• Operating Supply Voltage (min): -3.135/3.135V
• Operating Supply Voltage (typ): -3.3/3.3V
• Operating Supply Voltage (max): -3.465/3.465V
• Package Type: TSSOP
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 20
• Lead Free Status / RoHS Status: Not Compliant

This section provides information on power dissipation and junction temperature for the ICS85357-11.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS85357-11 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
moderate air flow of 200 linear feet per minute and a multi-layer board, the appropriate value is 66.6°C/W per Table 8 below.
Therefore, Tj for an ambient temperature of 70°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
85357AG-11
ABLE
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.
8. T
Power (core)
Power (outputs)
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
70°C + 0.203W * 66.6°C/W = 83.5°C. This is well below the limit of 125°C
JA
A
HERMAL
= Ambient Temperature
= Junction-to-Ambient Thermal Resistance
R
ESISTANCE
MAX
_MAX
MAX
= V
(3.465V, with all outputs switching) = 173.3mW + 30mW = 203.3mW
= 30mW/Loaded Output pair
CC_MAX
JA
* I
EE_MAX
FOR
JA
20-
P
CC
= 3.465V * 50mA = 173.3mW
by Velocity (Linear Feet per Minute)
= 3.3V + 5% = 3.465V, which gives worst case results.
OWER
PIN
JA
TSSOP, F
* Pd_total + T
C
www.idt.com
ONSIDERATIONS
ORCED
A
7
114.5°C/W
4:1
73.2°C/W
C
ONVECTION
0
OR
2:1, C
LVPECL / ECL M
98.0°C/W
66.6°C/W
RYSTAL
200
JA
O
must be used. Assuming a
ICS85357-11
SCILLATOR
88.0°C/W
63.5°C/W
500
REV. D OCTOBER 4, 2010
ULTIPLEXER
-
TO
-3.3V