AN869 STMICROELECTRONICS | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 4
Technical content
This application note is about the limit of Tj max given in the datasheet of SCHOTTKY rectifiers. with a junction temperature higher than Tj max. Table 1 shows the Tj max specified in the datasheet for the different families of SCHOTTKY diodes. Table 1. Tj max versus SCHOTTKY family This application note describes the rules for the calculation of the limit before thermal instability is reached. blocking of the diode: (1 - δ), thermal resistance of the heatsink: Rth(c-a) ...).
The limit of the reverse current at VR and Tj max before reaching thermal runaway is given by: Where c is a thermal coefficient c ≈ 0.055 Rth(j-a) = Rth(j-c) + Rth(c-a) We have: IR (15V, Tj max) = 242mA Tj max is given by: Tj max = 127°C Second example: Application parameters: (1-δ) = 0.5 VR = 5V Rth(c-a) = 18.5°C/W Diode parameters (STPS10L25D): IR max (5V, 125°C) = 125mA Rth(c-a=) = 1.6°C/W We have IR (5V, Tj max) = 363mA and Tj max = 144°C CONCLUSIONS This application note shows that the maximum limit of Tj of the SCHOTTKY diodes given in the datasheet is mainly due to the thermal runaway phenomenon. This limit doesn’t only depend on diode parameters but also application parameters. In the first example corresponding to a typical application we will find Tj max given in the datasheet. The second example shows that in some applications SCHOTTKY diodes can be used with a junction temperature higher than the Tj max given in the datasheet. IR 15VT j m a x,() 1 Tjmax 125= 1 C----In IR 15VT j m a x,()
REVISION HISTORY
Table 2. Revision History 10-May-2004 2 Stylesheet update. No content change.
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publicati on are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners © 2004 STMicroelectronics - All rights reserved STMicroelectronics GROUP OF COMPANIES Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States