Electronic Design


MSOP-Packaged DSL Driver Features Two-Bit Digital Programmability
Linear Technology Corp.
(408) 432-1900; fax (408) 434-6441; www.linear-tech.com.

The LT1969 is a miniature CPE line driver for ADSL/VDS/xDSL applications. The device consists of a dual, high output power (±300 mA) op amp. This high-speed op amp (gain bandwidth = 700 MHz) features adjustable supply current and low distortion (THD = −72 dBc at 1 MHz). Packaged in a low-profile (1 mm thick) thermally enhanced MSOP 10-pin package, the LT1969 occupies only 15 mm2 of board space. The wide output swing is ±4.3 V with ±6-V supplies into a 25-Ω load. The two-digit programmability allows the device to be programmed for up to four driver conditions. In 1000-unit quantities, pricing for the LT1969CMS starts at $2.95 each.

High-Speed Line Drivers, Receiver Target CPE Modems
Texas Instruments Inc.
(800) 336-5236; www.ti.com.

A family of high-speed line drivers and a high-speed receiver are designed for customer premise equipment (CPE) modems used in ADSL broadband communications. The THS604x/5x/9x ADSL CPE line driver family features low differential output noise for this type of device. According to the company, this family achieves a reduction of up to 40% from earlier solutions. The OPA2822 ADSL line receiver features a very low input noise in a wideband unity-gain stable voltage feedback architecture. The receiver functions as a front end for 14- and 16-bit analog-to-digital converter (ADC) interfaces for up to 5-MHz signals. The company also says the combination of these devices decreases the overall noise floor of the downstream signal. This generates improved data rates and wider service areas for ADSL modem deployments.

VR Devices Are Replacements For Variable Resistors And Trimmers
Analog Devices Inc.
(800) ANALOG-D; fax (781) 937-1021; www.analog.com.

The AD5200 and ADS5201 are low-cost, 256- and 33-position digitally controlled variable resistor (VR) devices. According to the company, these devices perform the same electronic adjustment function as potentiometers and trimmers. Packaged in micro-SOIC packages, the devices are suited for use in communications and multimedia applications, including audio/video equipment and PCMCIA cards. Full analog parameter characterization of differential nonlinearity error, total harmonic distortion, noise, and bandwidth assures complete system information for the rheostat, potentiometer-divider mode circuit connections. While the devices offer standard SPI interfaces, end-to-end terminal resistances are available in 10 and 50 kΩ each. Both parts operate on single power supplies from 2.7 to 5.5 V or dual supply ±2.7 V for ground-reference signals.

The AS5200 and AD5201 are priced at $0.90 and $0.68 each in 1000-piece quantities, respectively.

6-A Current Sense Transformers Suit Feedback Control Applications
(858) 674-8100; www.pulseeng.com.

The members of the P820xT series of 6-A surface-mount current sense transformers suit the dc-dc converter market. The transformers' applications include feedback control, overload sensing, detecting load-drop, or circuit shutdown. The devices are specifically designed to detect ac current changes and supply an output for control circuitry.

The series is rated for currents up to 6 A. It includes a full range of turns ratios from 1:20 to 1:125 with inductance values from 80 to 3000 µH. The low-profile transformers measure only 0.19 in. high. According to the company, these devices are suited for high-density, low-height dc-dc converter applications. Their flat-top design with the fixed clip makes them compatible with pick-and-place applications. The devices are available in trays or tape-and-reel packaging. In 25,000-unit quantities, the devices cost $0.63 each.

Current-Sense Amplifier Fits In Tiny SC70 Package
Maxim Integrated Products
(800) 998-8800; www.maxim-ic.com.

The MAX4073 is a low-cost, precision current-sense amplifier in a small SC70 package. This device uses a small, high-side, external sense resistor. It provides a voltage output proportional to the current being sensed. Internal resistors are trimmed to provide accurate gains of 20, 50, or 100 V/V. The devices feature a typical full-scale accuracy of 0.5%. The input common-mode range is from 2 to 28 V, allowing operation with a variety of batteries and wall-cube chargers. The device's wide 1.8-MHz bandwidth suits it for use inside battery-charger control loops.

The MAX4073 operates from a single 3- to 28-V supply, drawing only 500 µA of quiescent current. The device is specified for operation over the −40°C to 125°C automotive-temperature range. In 2500-unit quantities, the MAX4073 starts at $0.70.

20-Bit Low-Power DAC Features Built-In Headphone Amplifier
AKM Semiconductor
(408) 436-8580; fax (408) 436-7591; www.akm.com.

The AK4362 is a 20-bit, two-channel digital-to-analog converter (DAC) that offers an independent DAC and analog attenuator. These components provide a monaural output to drive a speaker. The device can function as the playback device while allowing for voice or other analog signals to be passed to the headphone amplifiers or routed to the speaker output. The AK4362 features a third built-in DAC to allow an external speaker amplifier to be controlled independently for volume control and mixing functions. The headphone amplifier circuit has an advanced mute circuit, eliminating the common problem of popping when the power is switched on or off.

The AK4362 is available in a 28-pin QFN package. It costs $3.31 in 10,000-unit quantities.

ADC Features Low Power Dissipation, 500-MHz Bandwidth
Signal Processing Technologies Inc.
(719) 528-2300; fax (719) 528-2370; www.spt.com.

The SPT7720 is an 8-bit, 200-Msample/s analog-to-digital converter (ADC). The device features low 430-mW power dissipation. It also features a high 500-MHz bandwidth. According to its manufacturer, digital instrumentation such as digital sampling oscilloscopes can take advantage of the SPT7720's 200-Msample/s sample rate and linearity (ILE/DLE at ±0.5 LSB typical) to accurately represent complex analog signals. This device is fully functional and pin-compatible with the AD9054A.

The SPT7720 is available in a 44-lead TQFP surface-mount package. It operates over the
−40°C to 85°C industrial-temperature range. In 1000-unit quantities, it costs $29.80 each.

Audio Amplifier Family Suits Portable Applications
National Semiconductor Corp.
(408) 721-5000; www.national.com.

A family of five audio products suits demanding applications in notebook computers, PDAs, cellular phones, MP3 players, information appliances, and other battery-powered devices. The LM4900 audio power amplifier operates at 2.0 to 5.0 V, with specified operation at 2.6 V. The device delivers 265 mW into 8 Ω at 1% THD+N. The LM4892 audio amplifier includes headphone capability. It features ultra-low current shutdown (0.1 µA) with a low logic level to provide battery savings with fewer components. The LM4819 is a monobridged audio power amplifier that provides high-quality speaker sound down to low 2-V operation. It offers a shutdown mode that only draws 0.7 µA . The LM4809 and LM4910 Boomer headphone amplifiers have low- or high-shutdown mode with less than 0.6 µA draw in shutdown. While the LM4809 has a shutdown low, the LM4810 has a shutdown high. The LM4900 costs $0.50 and the LM4892 costs $0.80. While the LM4819 costs $0.19, the LM4809 and LM4810 costs $0.17. All pricing is for 1000-unit quantities.

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