Fairchild’s Motion SPM® Smart Power Modules integrate drive and protection circuitry for all sorts of industrial motion and motor control applications into a single package.
Fairchild recently introduce the SPM 7 Module for compact motor control applications of up to 50W. Seldom do these applications have room for heatsinks, which means estimating junction temperature (TJ) to ensure system reliability is critical. What follows are a few methods that can be used for calculating junction temperate of the SPM 7 series.
Motion SPM 7 Series Overview The high-performance SPM 7 modules series combine a number of devices – including a high-performance FRFET® MOSFET and halfbridge gate driver IC’s – to provide a fullyfeatured, high-performance inverter within a single PQFN package (Fig. 1). The key design objective of the Motion SPM 7 series was of course to provide a solution for compact and reliable inverter design when assembly space is constrained. Think of systems such as small pedestal and ceiling fan motors, air conditioner indoor/outdoor fans, and water pumps.
Estimating Junction Temperature There are four methods used to measure the junction temperature. A. Direct Measurement (TJ sensing by IR Camera) B. TC_TOP measurement (Measuring Case Temperature TC_TOP Sensing by IR Camera) C. TP Measurement (PCB Temperature TP Sensing by Thermocoupler) D. VTS Measurement (Junction Temperature of the High Voltage IC THVIC Sensing by VTS)
Summary There are pros and cons to each method that are weighed against cost, simplicity and tolerance to variations. The table below summarizes the different aspects of each method.
|A||Direct Measurement||De-cap Facility, IR Camera||Accuracy||High-cost||Measuring Junction Temperature T|
|B||TC_TOP Measurement||IR Camera||Easy Measurement||High-cost||Measurement for Case Temperature TC_TOP|
|C||TP Measurement||Thermal Recorder||Easy Measurement||Large variation dependent upon attaching point||Measurement for PCB Temperature TP|
|D||VTS Measurement||Voltage Meter||Easy & Low-cost Measurement||Correlation is required between THVIC and TJ||Above methods can be used for the TJcorrelation|
- Air conditioner indoor / outdoor fans
- Pedestal fans / ceiling fans
- Small pumps
- Small power AC motor drives
- Fully-featured, high-performance inverter output stage for AC induction, brushless DC (BLDC) and permanent magnet synchronous motors (PMSM)
- Optimized for Low Electromagnetic Interference
- HVIC Temperature-Sensing Built-In for Temperature Monitoring
- Separate Open-Source Pins from Low-Side MOSFETs for Three-Phase Current-Sensing
- Active-HIGH Interface, Works with 3.3 / 5 V Logic, Schmitt-trigger Input
- HVIC for Gate Driving with Under-Voltage Protection and Interlock Function
- Isolation Rating: 1500 Vrms / min.
- Moisture Sensitive Level (MSL) 3
- UL Certified No. E209204 (UL1557)
- RoHS Compliant