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- Three-Phase Brushless DC Motor Pre-Driver IC
ALLEGRO MICROSYSTEMS, Inc. has introduced a three-phase brushless DC motor pre-driver with outputs for direct high current gate drive of an all N-channel power MOSFET three phase bridge with a maximum supply voltage of 38 V. Allegro's A4936 device has three Hall-element inputs, a sequencer for commutation control, fixed off-time pulse width modulation (PWM) current control, and locked-rotor detection. Output current is scaled by the capability of the external MOSFETs. Locked rotor detection delay is set by an external capacitor on the CLD terminal. The PWM, DIR, BRAKE and STOP inputs can be used to control motor speed, position, and torque. Motor speed can be determined using motor FG coil signal that is amplified and shaped with the internal differential amplifier and comparator to produce a digital FGS output. The external MOSFETS can be pulse-width-modulated using an external signal on the PWM input, or using the internal PWM current regulator. The driver's synchronous rectification feature reduces power dissipation by turning on the appropriate MOSFETs during current decay.
The Hall elements can be inexpensive types when used with internal noise filtering to prevent false commutation signals. The A4936 provides a regulated 7.5 V supply to power the three Hall elements. Internal circuit protection includes thermal shutdown with hysteresis, under voltage lockout, and dead time protection. The operating temperature range is -20°C to 105°C. The A4936 is supplied in a 5 mm × 5 mm, 32-terminal QFN package with tin lead frame plating. It is priced at $1.00 in quantities of 1,000.
- Front-End Power Supplies
THE EFE Series of embedded front-end power supplies includes the 300-W EFE-300 and the 400-W EFE-400. Both single-output power supplies deliver 133% peak-power capability for 10 sec and offer efficiency of up to 90%. In addition, the products employ an 8-bit microcontroller for full digital control of the output and to handle housekeeping routines, resulting in a 25% parts count reduction to achieve a 45% smaller and up to 56% lighter design compared to competitive products. Power densities of up to 22 W/in.3 are achieved under peak-load conditions and 16.6 W/in.3 under continuous loading. Featuring a 1U profile, the EFE-300 measures 3 in. × 5 in. × 1.34 in., while the EFE-400 measures 3 in. × 6 in. × 1.34 in.
- 5A DC/DC Converter Generates Positive or a Negative Voltage
THE LT3957 from Linear Technology Corporation is a highly versatile DC/DC converter for boost, flyback, SEPIC and inverting power supply applications. This device operates over an input voltage range of 3V to 40V, has an onboard 5A/40V power switch and achieves efficiencies up to 96%, making it well suited for industrial, automotive, medical and telecom applications. The LT3957 can generate either a positive or negative regulated output voltage with its two internal voltage feedback error amplifiers and reference voltages. One set is for positive output voltages, and the other is for negative output voltages, both off a single feedback pin. With a programmable fixed or synchronizable operating frequency from 100kHz to 1MHz, designers can choose a wide range of inductors and capacitors to optimize size, performance and cost. Its current-mode control results in stable operation over a wide range of supply and output voltages. The device supports designs using only ceramic capacitors, enabling a smaller solution size. Additional features include programmable soft-start, adjustable input undervoltage lockout, as well as output overvoltage and overcurrent protection. The LT3957 operates from a -40°C to 125°C temperature range and is offered in a 5mm × 6mm QFN-36 package with additional pin spacing to support high voltage operation. The 1000-piece price starts at $2.95 each.
- Brushless 8mm Motor
MAXON'S EC8 brushless dc motor offers continuous current up to 0.95 mNm, nominal speed up to 80,000 rpm, and an exceptional efficiency rating of 70%. The motor is available with or without Hall sensors and with 6 V, 12 V and 24 V windings. It can be combined with the planetary gearhead GP 8A. 1-quadrant amplifiers serve as controllers; the DEC 24/1, directly connected via flexprint and the DEC Module 24/2, a miniature plug-in module. The EC8 motor was produced according to the most rigid Medical Standard ISO 13485 and is suited for applications such as sampling robotics, portable analyzers, metering systems, instrumentation or inspection robots.
Fall River, MA
- Spread-Spectrum Clock Generators Provide Superior EMI Noise Reduction
MAXIM INTEGRATED Products' MAX31C80/MAX31D80 spread-spectrum generators provide reportedly the industry's best-in-class EMI peak-noise reduction. The MAX31C80/MAX31D80 also offer the designer unprecedented flexibility to use any clock frequency or crystal to achieve the desired output frequency. The devices use a high-quality, programmable, fractional PLL with low jitter (< 75ns) to provide a 2MHz to 134MHz output, regardless of crystal or clock input. An active, spread-spectrum dither for the EMI noise spread achieves the flattest spread available without typical energy/noise spikes at the edges or center of the spread range. The integrated crystal oscillator, buffered oscillator output, programmable fractional PLL, and spread-spectrum generator also reduce component count, size, and ultimately, cost. The devices' spread-spectrum output is ideal for driving microprocessors, memory, and bus clocking, which generate large EMI peaks at specific frequencies. The MAX31C80/MAX31D80 provide a buffered clock-reference output for driving communications where the spread-spectrum output is unacceptable. By combining the crystal oscillator and buffered clock output with the factory-programmable, spread-spectrum output, these clock generators are the only clocking device many systems need. The MAX31C80/MAX31D80 are specified to operate over temperatures of -40° to +125°C. They are available in a 3mm × 3mm × 0.8mm, 10-pin TDFN package. Pricing begins at $1.51 (1000-up, FOB USA).
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