AN3338 datasheet(31/72 Pages) STMICROELECTRONICS

Part #	AN3338

Description	In recent years the variable speed motor control market has required high performance

PDF	72 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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31 / 72 page

Doc ID 18441 Rev 4

31/72

AN3338

Electrical characteristics and functions

where T is the temperature in Kelvin, B and R25, respectively, are a constant value in the

SLLIMM working range and the resistance value at 25 °C, both parameters are shown in the

datasheet.

An easy circuit, using a voltage divider, for both overtemperature protection and

temperature monitoring, is shown in

Figure 20:

The external comparator is used to send a shutdown signal to the SLLIMM in case of

overtemperature. The VNTC_th is a threshold voltage, fixed by design, and connected on the

non inverting input, whilst the inverting input is connected on a voltage divider based on the

NTC and ROT resistors. When voltage on the inverting input exceeds the VNTC_th value the

comparator triggers, pulling down the SD and, consequently, switching off the IGBTs.

Figure 19. NTC resistance vs. temperature curve

Figure 20. Example of overtemperature protection circuit

NTC

SLLIMM

NTC_th

AN3338 Datasheet(PDF) 31 Page - STMicroelectronics