TLS805B1 datasheet(22/26 Pages) INFINEON

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Data Sheet

Rev. 1.2 2016-01-11

TLS805B1SJ/LDV

Application Information

• IQ: output current

• Iq: quiescent current

The maximum acceptable thermal resistance RthJA can then be calculated:

(6.3)

with

• Tj,max: maximum allowed junction temperature

• Ta: ambient temperature

Based on the above calculation the proper PCB type and the necessary heat sink area can be determined with

reference to the specification in “Thermal Resistance” on Page 10.

Example

Application conditions:

VI = 13.5 V

VQ = 5 V

IQ = 35 mA

Ta = 105 °C

Calculation of RthJA,max:

PD =(VI – VQ) x IQ + VI x Iq

= (13.5V – 5V) x 35 mA + 13.5 V x 0.0115 mA

= 0.2975 W

RthJA,max=(Tj,max – Ta) / PD

= (150 °C – 105 °C) / 0.2975 W

= 151.2 K/W

As a result, the PCB design must ensure a thermal resistance RthJA lower than 151.2 K/W. According to

“Thermal Resistance” on Page 10, for both TLS805B1SJV and TLS805B1LDV at least 300 mm² heatsink area

is needed on the FR4 1s0p PCB, or the FR4 2s2p board can be used.

6.5

Reverse Polarity Protection

TLS805B1 is not self protected against reverse polarity faults. To protect the device against negative supply

voltage, an external reverse polarity diode is needed, as shown in Figure 7. The absolute maximum ratings of

the device as specified in “Absolute Maximum Ratings” on Page 8 must be kept.

6.6

Further Application Information

• For further information you may contact http://www.infineon.com/

RthJA max

Tjmax

–

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TLS805B1 Datasheet(PDF) 22 Page - Infineon Technologies AG