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November 28, 2011

IDT 89HPES32H8G2 Data Sheet

Thermal Considerations

This section describes thermal considerations for the PES32H8G2 (23mm2 FCBGA484 package). The data in Table 17 below contains information

that is relevant to the thermal performance of the PES32H8G2 switch.

Note: It is important for the reliability of this device in any user environment that the junction temperature not exceed the TJ(max) value

specified in Table 17. Consequently, the effective junction to ambient thermal resistance (

θJA) for the worst case scenario must be

maintained below the value determined by the formula:

θ

JA = (TJ(max) - TA(max))/P

Given that the values of TJ(max), TA(max), and P are known, the value of desired θJA becomes a known entity to the system designer. How to

achieve the desired

θ

JA is left up to the board or system designer, but in general, it can be achieved by adding the effects of θJC (value

provided in Table 17), thermal resistance of the chosen adhesive (

θ

CS), that of the heat sink (θSA), amount of airflow, and properties of the

circuit board (number of layers and size of the board). It is strongly recommended that users perform their own thermal analysis for their own

board and system design scenarios.

Symbol

Parameter

Value

Units

Conditions

TJ(max)

Junction Temperature

125

oC

Maximum

TA(max)

Ambient Temperature

70

oC

Maximum for commercial-rated products

85

oC

Maximum for industrial-rated products

θJA(effective)

Effective Thermal Resistance, Junction-to-Ambient

15.2

oC/W

Zero air flow

8.5

oC/W

1 m/S air flow

7.1

oC/W

2 m/S air flow

θJB

Thermal Resistance, Junction-to-Board

3.1

oC/W

θJC

Thermal Resistance, Junction-to-Case

0.15

oC/W

P

Power Dissipation of the Device

10.08

Watts

Maximum

Table 17 Thermal Specifications for PES32H8G2, 23x23 mm FCBGA484 Package