SBOA523 July 2021 TMP390 , TMP392
In many applications, designers need to be able to detect and react to thermal events, especially in thermally sensitive systems. One way to implement this is to use a temperature switch. This can be done using only discrete components or using the TMP390 or TMP392, as discussed within this report. Table 3-1 summarizes the differences in using only discrete components and using the TMP390 or TMP392.
TMP390, TMP392 | Discrete Solutions | TMP390, TMP392 Benefits | |
---|---|---|---|
Smallest Circuit Area | 6.55 mm × 4 mm (26.2 mm2) | 7.22 mm × 6.25 mm (45.1 mm2) | 42% smaller PCB area |
Minimum Number of External Components | 4 resistors + 1 cap | 8 resistors (including thermistor) + 1 caps + 1 op amp | 50% fewer components |
Minimum Number of 1% Tolerance Resistors | 4 | 7 | 43% direct cost saving for 1% resistors |
PCB Consideration | No vias | Minimum of 3 vias | Improved PCB manufacturing costs |
Trip Test | Yes | No | Supports production self-test |
Circuit Flexibility | No re-design, simple swap of resistors | Circuit needs to be re-designed and tested | Faster time to market |
Dual Trip Temp with Single Output | Open drain outputs; simple tie-off | Need additional circuit to connect output of 2 op amps | Flexible and simpler design layouts |
Accuracy | Higher | Lower | Allows for better operation in thermally sensitive systems |
Power Consumption | Very Low | Very High | Allows for use of a battery as a power supply and increases portability and flexibility of system |
Overall Cost | Lower | Higher | Reduced manufacturing costs due to less components |
After extensive comparisons have been made between discrete solutions and the TMP390 or TMP392, it is evident that to reduce size, cost, power consumption, and have high accuracy, the TMP390 or TMP392 offer the best solution. In addition to its low price and small size, it is easy to implement and integrate into a system, with high flexibility in controlling the desired thresholds by changing external resistors that can be chosen via a lookup table.