Optimizing the use of input voltage and maximizing output current are key benchmarks for power management devices designed for motor control applications. Managing thermal properties is vital, along with adding value to the design by adding built-in features and functionality.
With product trends moving toward more miniaturized designs, especially for handheld and battery-powered devices, the focus is on form factor and cost. "The real driving force for our new 3908 part, beyond the normal specifications of the output current and input voltage, is the package size," says Tim Rowan, strategic marketing manager for Allegro MicroSystems Inc. By specifically targeting an application for cell phone lens' covers, a new eight-pin DFN package that is only 2 x 2 mm is able to replace a package that was twice the size.
NEW LOW-VOLTAGE, BI-DIRECTIONAL DC MOTOR DRIVER
Allegro MicroSystems Inc. has introduced a new low-voltage bi-directional dc motor driver with a typical input voltage range of 3.0 to 5.5V and output currents up to 500 mA. The unique full-bridge output incorporates source side linear operation to allow a constant voltage supply across the motor coil. This regulated output minimizes motor voltage change due to I*Rds (on) variation and battery voltage tolerance. Allegro's new motor driver is targeted at the portable and instrumentation markets.
Two logic inputs are provided to control the motor direction of rotation, brake and standby (< 500 nA supply current) modes and to allow optional PWM of the sink drivers. Internal protection circuitry includes thermal shut down, under voltage lockout and crossover (shoot through) protection.
SINGLE-CHIP INTERLEAVED PFC CONTROLLERS
Texas Instruments' UCC28070 and UCC28060 controllers provide an interleaved power factor correction (PFC) control circuit for multi-kilowatt communications, server and industrial systems. The two-phase, average current-mode 28070 controller allows designers to simplify their power design, increase system reliability and achieve a greater than 0.9 power factor rating, which also improves energy efficiency.
Key features include interleaved average current mode PWM control and an advanced current synthesizer for superior efficiency, accurate current sensing and high power factor. The 28070 also provides highly linear multiplier output with internal voltage feed-forward correction for near unity power factor, programmable switching frequencies (30 to 300 kHz), selectable frequency dithering for reduced EMI and phase management for high-efficiency, light-load operation.
THREE PHASE FIELD EFFECT TRANSISTOR PRE-DRIVER
The 33937 is a field effect transistor (FET) pre-driver from Freescale Semiconductor designed for three-phase motor control and similar applications. The integrated circuit (IC) uses SMARTMOSTM technology, and contains three high side FET pre-drivers and three low side FET pre-drivers. Three external bootstrap capacitors provide gate charge to the high side FETs. The IC interfaces to a MCU via six direct input control signals, an SPI port for device set up and asynchronous reset, enable and interrupt signals. Both 5.0 and 3.0V logic level inputs are accepted and 5.0V logic level outputs are provided. The 33937 is fully specified from 8.0 to 40V, covering 12 and 24V automotive systems, and offers an extended operating range from 6.0 to 58V.