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Electronic Design


6-Channel 24-Bit DAC Features 192-kHz DVD-Audio Sampling
The AK4355 suits DVD/DVD-audio applications. This 6-channel, 24-bit DAC has a 192-kHz DVD-audio sampling format. According to the company, this device provides a low-cost solution for multichannel audio systems.

This DAC features a built-in digital volume control for adjustment of balance between channels. It maintains a dynamic range of 106 dB and satisfies Dolby Digital standards. This device achieves high-quality sound through an advanced multibit system in the Δ-Σ modulator. Its anti-jitter performance matches that of switched capacitor DACs. Additional features include a 24-bit 8x digital filter with switchable slow roll-off. It also features a channel-independent digital attenuator and a three-wire serial control interface.

The AK4355 comes packaged in a 28-pin VSOP. In 1000-unit quantities, it costs $4.15.

AKM Semiconductor Inc., 2001 Gateway Pl., Ste. 650W, San Jose, CA 95110; (408) 436-8580;

SAW Filters Come In Ultra-Small Packages For WCDMA Applications
Members of the F6 Series of SAW filters come in ultra-small packages for Wideband CDMA (WCDMA) applications. They suit high-frequency applications in the 1.95- to 2.14-GHz range.

Based on lithium tantalate (LiTaO3), the SAW filters use a "ladder" design. This configuration combines serial and parallel on-chip resonators for an insertion loss of less than 3.5 dB. This also ensures high stop-band attenuation. These devices provide low inductance and high resistance to shock, mechanical vibration, and climate changes. An impedance of 50 Ω eliminates the need for external matching circuits.

Four SAW filters are available in various package sizes to meet design requirements. The F6CE-1G9500-L2ZP transmitter and F6CE-2G1400-L2ZQ receiver are housed in a 3- by 3-mm package. The F6CP-1G9500-L21P transmitter and the F6CP-2G1400-L21Q receiver are housed in a 2.5- by 2-mm package. All are packaged in surface-mount leadless chip carrier (LCC) packages using the industry's latest flip-chip technology. Pricing begins at $1.80 each in 10,000-unit quantities.

Fujitsu Microelectronics Inc., 3545 N. First St., San Jose, CA 95134-1804; (408) 922-9000;

SOT-23 Packaged Oscillator Requires Only One Resistor
The LTC1799 is a SOT-23 packaged oscillator IC that generates "any frequency" from 1 kHz to 30 MHz. The frequency can be accurately set within ±2.5% by adding a single 1% resistor (±1.6% accuracy is achieved by using a 0.1% resistor). This device eliminates the need for a crystal, ceramic resonator, capacitor, or external reference clock.

Proprietary circuitry in the LTC1799 ensures accuracy is maintained over all supply and temperature variations. Drift is typically less than 0.004%/°C and 0.05%/V. According to the company, this device requires a fraction of the power of comparable solutions. Over the −40°C to 85°C range, the maximum supply current at 5 V is 2.4 mA for a 10-MHz output.

The LTC1799 suits the synchronization of switching power supplies and drives switched capacitor filters. It's available in a 5-lead SOT-23 package over the commercial and industrial temperature ranges. In 1000-unit quantities, the LTC1799 costs $1.55 each.

Linear Technology Corp., 1630 McCarthy Blvd., Milpitas, CA 95035-7417; (408) 432-1900; fax (408) 434-6441;

ADC Guarantees 24 Bits Of No-Missing-Code Performance
The ADS1240 analog-to-digital converter (ADC) operates from 2.7 to 5.25 V. It provides power consumption as low as 570 µW. Its Δ-Σ architecture guarantees 24 bits of no-missing-code (NMC) performance.

This device incorporates a four-channel multiplexer, burn-out current sources, a programmable gain amplifier (PGA), an input buffer, and an offset digital-to-analog converter (DAC). Additional features include a selectable data-output rate, a single-conversion cycle-setting filter, an external differential voltage reference, four programmable digital I/Os, on-chip calibration, and a standard SPI serial interface. The device's PGA provides for gains of up to 128. Linearity error is guaranteed to be less than ±0.0015% of full scale. An eight-channel version, the ADS1241, is available for applications requiring additional input channels.

According to the company, this ADC is suited for high-resolution measurement applications, including industrial process control, portable instrumentation, liquid/gas chromatography, weight scales, smart transmitters, and pressure transducers. The ADS1240 comes packaged in an SSOP-24. In 1000-unit quantities, it costs $3.60.

Texas Instruments Inc., P.O. Box 954, Santa Clarita, CA 91380; (800) 477-8924, ext. 4500;

Low-Voltage Supervisor IC Boasts Ultra-Low Quiescent Current
The MIC2775 low-voltage supervisor IC monitors power supplies as low as 1.5 V. Available in SOT-23-5 packaging, it features a choice of factory-programmed voltage options and ultra-low quiescent current.

The availability of factory-programmed voltage options eliminates external components. The industry-standard package and pinout make it a drop-in upgrade for previous generations of supervisor ICs. The quiescent power-supply current is 3.5 µA. Active-high and active-low reset outputs are featured. A manual reset input is featured as a reset switch. It also can be used to daisy-chain onto existing power supervision circuitry. Operating voltage ranges from 1.5 to 5.5 V. The MIC2775 is manufactured using the company's biCMOS process.

In 1000-unit quantities, this device costs $0.78 each.

Micrel Inc., 1849 Fortune Dr., San Jose, CA 95131; (408) 944-0800; fax (408) 944-0970;

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