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©2016-2023 Renesas Electronics Corporation

November 20, 2023

8P34S2108 Datasheet

2. Junction Temperature

Junction temperature, Tj, is the temperature at the junction of the bond wire and bond pad directly affects the reliability of the device. The

maximum recommended junction temperature is 125°C. Limiting the internal transistor junction temperature, Tj, to 125°C ensures that

the bond wire and bond pad temperature remains below 125°C.

The equation for Tj is as follows: Tj = JA * Pd_total + TA

Tj = Junction Temperature

JA = Junction-to-Ambient Thermal Resistance

Pd_total = Total Device Power Dissipation (example calculation is in Power Dissipation section above)

TA = Ambient Temperature

In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance JA must be used. Assuming no air flow

and a multi-layer board, the appropriate value is 22.4°C/W per Table 12 below.

Therefore, Tj for an ambient temperature of 85°C with all outputs switching is:

85°C + 1.4175W * 22.4°C/W = 116.8°C. This is below the limit of 125°C.

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 (multi-layer).

Package Outline Drawings

The package outline drawings are located at the end of this document and are accessible from the Renesas website (see Ordering

Information for POD links). The package information is the most current data available and is subject to change without revision of this

document.

Marking Diagram

Table 12. Thermal Resistance JA for 48-lead VFQFPN, Forced Convection

JA (°C/W) vs. Air Flow (m/s)

Meters per Second

0

1

2

48-lead VFQFN Multi-Layer PCB, JEDEC Standard Test Boards

22.4

18.9

17.4

▪ Line 1, line 2, and line 3 indicates the part number.

▪ Line 4:

• “#” indicates stepping.

• “YYWW” indicates the date code (“YY” are the last two digits of the year, and

“WW” is a work week number that the part was assembled.

• “$” indicates the mark code.