Linear Technology's LTC3823 synchronous stepdown dc-dc controller includes differential output-voltage sensing, fast transient response, integrated phase-lock loop synchronization and output-voltage tracking. The differential amplifier provides true differential remote output-voltage sensing of both the positive and negative terminals. This enables high accuracy regulation in high current applications where resistive losses occur through via and trace run interconnect.
The IC can operate at duty cycles ranging from 2% to 90% and is able to develop output voltages from 0.6 V to 90% of VIN (0.6 V to 3.3 V with remote sense). The input-voltage range is from 4.5 V to 30 V. Constant on-time architecture allows the control loop to respond instantly to load steps.
The LTC3823 is offered in a 28-lead narrow SSOP or 32-lead 5-mm × 5-mm QFN package and has an operating temperature range from -40°C to 85°C. The 1000-piece price starts at $2.75 each.
Microchip Technology's MCP3421 is a low-power 18-bit delta-sigma ADC featuring an integrated voltage reference and programmable gain amplifier on-chip.
The device uses an I2C-compatible serial interface and operates from a single power supply (2.7 V to 5.5 V). Current consumption is 155 µA at 5 V during continuous conversion, extending battery life in portable measurement devices. Additionally, users can select the gains of 1, 2, 4 or 8 before the analog-to-digital conversion takes place.
The MCP3421 ADC is available in a 6-pin SOT-23 package for $1.71 each in 10,000-unit quantities.
International Rectifier's IRF6643PbF is a 150-V DirectFET MOSFET for isolated dc-dc converters and operates from 36-V to 75-V universal telecommunications input and 48-V fixed input systems. Combining DirectFET packaging technology and next-generation HEXFET power MOSFET silicon, the new DirectFET device achieves a current rating up to 35 A, while providing superior thermal performance and higher efficiency in an SO-8 footprint.
The IRF6643TRPbF costs $1.24 each in quantities of 10,000 and comes in the medium-sized DirectFET package.
El Segundo, Calif.
The MAX8640Y/MAX8640Z from Maxim Integrated Products are 500-µA, high-efficiency stepdown dc-dc converters in an SC70 package. They use a switching scheme to reduce external component size and draw only 24 µA of quiescent current, thus providing light-load efficiency. This makes them ideal for generating low-voltage microprocessor core supplies for portable applications powered by a single-cell Li+ or three-cell NiMH/NiCd batteries.
The high integration of the dc-dc converters permit a footprint of 13.4 mm2. The MAX8640Y/MAX8640Z integrate a synchronous rectifier. These devices are available in a 2-mm × 2.1-mm SC70, and a 1-mm × 1.5-mm microDFN is planned. Prices start at $1.58 in quantities of 1000.
Maxim Integrated Products
Switched Reluctance Motors
AMETEK Commercial Motors' GEN II INFIN-A-TEK switched-reluctance motor blowers incorporate a digital speed control that reduces the complexity of its components and pc-board design, increases its overall reliability. The digital controller also incorporates its own integrated power source. In addition, new speed control options are available, including the use of ac or dc control inputs as well as a resistor or potentiometer to vary speed.
The motor blower is available in 5.7-in.- and 7.2-in.-diameter tangential bypass and 5.7-in.-diameter Acustek low-noise peripheral bypass discharge models. There also are 9.1-in.-diameter high-suction and high-airflow FLO-TEK tangential bypass models.
DC Motor Controller
The ATA6831 driver IC from Atmel includes enhanced PWM performance for smooth dc motor control with reduced noise. The IC is designed to control, via a microcontroller, two dc motors or up to three different loads in automotive and industrial applications, such as flap control for a cash dispenser. Because of its high-voltage capability (up to 40 V), the ATA6831 also can be used in 24-V truck applications.
Pricing for the ATA6831 starts at $0.99 each in 10,000-piece quantities.
Tyco Electronics' HVS highly variable connector system permits end users to choose from more than 25 different connector modules, and quickly and easily mount or dismount up to six single or three double modules into a solid metal frame without tooling.
In most applications, the connector module system reduces the number of interfaces required. The wide range of connector modules cover standard applications as well as high-voltage, high-nominal current, pneumatic and high-density applications, with up to 25 poles per module available.
Positronic's Goldfish power connectors are ideal for applications requiring high power through a small space. Features include the support of ac or dc inputs, and combined signal and output power contacts in a single connector. Other features include sequential mating and blind mating. Solder, press-fit and cable-mount terminations are available. Product range is three package sizes with six contact variants.
Lightning Protection Resistor
Providing telecommunications design engineers with a surface-mount device that is less susceptible to surges, TT electronics' IRC Wire and Film Technologies Division has certified the HSF Series resistor to meet or exceed GR1089 lightning-strike specifications.
The resistive element provides a failure point during lightning-induced surges where the resistor material narrows in conventional thick-film devices. The unspiraled configuration of the HSF Series resistor removes this failure mode under these types of strikes. When components were subjected to 1000 V with the standard 10- × 1000-µs profile, the change in resistance was below 0.2%.
The HSF Series resistors feature a power rating of 1 W at 70°C and a working voltage of 350 V. The device is available in resistance values of 5.9 Ω, 11 Ω, 27 Ω, 68 Ω and 270 Ω. Pricing for the HSF Series resistors is $0.18 each in quantities of 10,000.
Intersil's ISL9003A low dropout regulator (LDO) delivers a PSRR of 90 dB at 1 kHz and limits output noise to 20 µVRMS, making the device well suited for use in GSM handsets. Load regulation is specified as < 0.1% voltage change across the full range of load current.
The LDO operates over a 2.3-V to 6.5-V input range and maintains an output voltage that is accurate to within ±1.8% over all operating conditions. Dropout voltage is typically 200 mV at the rated current. Quiescent current is 30 µA, reducing to 1 µA (max) in shutdown.
Features include soft-start, current limiting and thermal protection. The ISL9003A is available in a 5-lead SC-70 or 6-lead µTDFN and is priced at $1.27 each in 1000-unit quantities.
UV Conformal Coatings
HumiSeal announces its HumiSeal UV40 range of UV curable conformal coating materials. High-volume users in fields such as automotive and consumer electronics can gain access to the popular UV curable-coating class with its rapid cure speed, level of processing ease and thermal-cycling resistance.
One of the key benefits of the new UV material is its low viscosity. The material is also extremely flexible, particularly in response to thermal cycling. The HumiSeal UV40 range has exceptionally low solvents (less than 3% content).