Efficient smart power modules drive sub-100-W motors
The FSB70xxx series integrates an optimised gate driver for the built-in MOSFETs (using FRFET technology) to minimise EMI and losses, while also providing multiple on-module protection features including under-voltage lockouts, thermal monitoring, fault reporting and interlock function. Controlled dI/dt and dV/dt values in the switching waveforms minimise EMI. The PQFN package can save up to 50% of board space, and offers a low thermal resistance of 0.8degree/W. It measures 13 x 13 mm, and is the highlighted area on an example small-motor, axis-mounted PCB pictured above.
A company spokesman noted that although losses are substantially reduced over prior generation modules, they are not reduced by the same 50% as the package size, which therefore has better heat paths to the circuit board/substrate, with greater pad area, “and a design that is relatively immune to [soldering] voids.”
SPM 7 modules use Fairchild’s UniFET MOSFETs for 250 and 500V ratings; later, the same package will house a 600V version built with the company’s SuperFET devices.
Features include:
- A high-performance inverter output stage for AC induction, brushless DC (BLDC) and permanent magnet synchronous motors (PMSM);
- Optimised for low EMI;
- HVIC temperature-sensing built-in;
- Separate open-source pins from low-side MOSFETs for three-phase current-sensing;
- Active-HIGH interface, works with 3.3 / 5V logic, Schmitt-trigger input;
- HVIC for gate driving with under-voltage protection and interlock function;
- Isolation rating: 1500 Vrms / min.
Pricing ranges from $3.98 to $4.55 (1000).
Fairchild; www.fairchildsemi.com/ds/FS/FSB70250.pdf /
www.fairchildsemi.com/ds/FS/FSB70325.pdf /
www.fairchildsemi.com/ds/FS/FSB70625.pdf
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