|Home Analog Devices Feedback Subscribe Archives 简体中文 日本語|
This 3-page Application Note helps designers to achieve frequency stability and accuracy for the external oscillators used with video decoders, which typically require a 28.63636-MHz crystal with 50-ppm frequency stability in fundamental mode.
This 4-page Application Note describes the automatic and manual scaling algorithms used in the ADV7186 video decoder. Upscaling changes a low resolution video input to a higher resolution video output; downscaling changes a high resolution video input to a lower resolution video output to satisfy the back end device without the need for external memory.
The ADV8003 video signal processor with TTL logic and serial video inputs can de-interlace and scale input video. It generates and blends a bitmap-based on-screen display and provides the blended video to one or more output. Other available outputs include two HDMI transmitters, a six-DAC encoder with SD and HD support, and a TTL output. This application note describes how to pass 3D video through the ADV8003 and convert the 3D image to a 2D image.
This circuit provides a logarithmic audio volume control with glitch reduction using the AD5292 digital potentiometer in conjunction with the dual AD8676 and single AD8541 op amps, ADCMP371 comparator, and 7408 AND gates. This circuit provides low total harmonic distortion (THD), 46-dB maximum signal attenuation, and a shutdown function that attenuates up to 130 dB. The AD5292 can be placed in shutdown mode by executing a software shutdown command. This feature places the RDAC in a special state in which terminal A is open-circuited and wiper W is connected to terminal B. This circuit offers a logarithmic gain control function over a ±14 V (10 V rms) output voltage range and is capable of delivering up to ±20 mA output current. The AD5292 is programmable over an SPI-compatible serial interface. In addition, the AD5292 has an internal 20-times programmable memory that allows a customized volume setting at power-up. Well suited for many audio applications, this circuit provides low noise, low THD, high signal attenuation, low drift, and high voltage capability.
This low-cost, high-performance sound bar system can accept an analog stereo audio signal as an input and output up to eight channels of audio with discrete processing on each channel. The circuit offers low power consumption and high efficiency without sacrificing audio quality, making it ideal for small docking stations and portable media devices. The circuit is capable of driving headphones without the need of additional components. The ADAU1761 low power, stereo audio codec with integrated SigmaDSP® digital audio processing accepts two audio channels. It is optimized for audio applications and programmed using SigmaStudio development software for ease of use and faster development. The output of the ADAU1761 can send up to eight channels of digital audio data to the output amplifiers using the serial interface. The ADAU1761 allows different audio signal processing in each channel, such as volume control, custom equalization, filtering, and spatialization effects tuned to the specific speaker configuration. The ADAU1761 processes and converts analog audio to digital format and drives the SSM2518 power amplifier. The SSM2518 is a digital input class-D audio power amplifier that can output two channels of audio with a continuous power of 2 watts each into a 4 Ω load. The channel-mapping feature of the SSM2518 allows it to select the specific channel to output among those that are available in the interface, making it ideal for surround sound applications.
This professional-grade studio or live-performance microphone uses up to 32 analog MEMS microphones connected to op amps and a difference amplifier. Designed for low noise, its output is linear for acoustic inputs up to 131 dB SPL. Powered from a single 9-V battery, the ±9-V and 1.8-V power rails are generated from two voltage regulators. The ADMP411, which consists of a MEMS microphone element and an impedance-matching amplifier, has a frequency response that is flat to 28 Hz, making it ideal for full-bandwidth, wide dynamic range audio capture.
This circuit provides a complete solution for converting HDMI/DVI to VGA (HDMI2VGA) with an analog audio output. Using the low-power ADV7611 HDMI receiver, it is capable of receiving video streams up to 165 MHz. Powered from a USB cable, it works for resolutions up to 1600 × 1200 at 60 Hz. The circuit uses EDID content to ensure that the video stream from the HDMI/ DVI source is at the highest possible resolution supported by the HDMI source, converter, and VGA display.
This circuit interfaces an analog MEMS microphone to a microphone preamp. The ADMP504 consists of a MEMS microphone element and an output amplifier. Analog Devices’ MEMS microphones have a high signal-to-noise ratio (SNR) and a flat wideband frequency response, making them an excellent choice for high-performance, low-power applications. The SSM2167 low-voltage, low-noise mono microphone preamp is a good choice for use in low-power audio signal chains. This preamp includes built-in compression and noise gating, which gives it an advantage for this function over using just an op amp in the preamp circuit. Compressing the dynamic range of the microphone signal can reduce the peak signal levels and add additional gain to low level signals. Noise gating attenuates the level of signals below a certain threshold, so that only desired signals, such as speech, are amplified, and noise in the output signal is reduced. These features help to improve the intelligibility of the voice signal picked up by the microphone.
4-channel Sigma-Delta ADC for automotive audio
The ADAU1979 includes four high-performance ADCs, a voltage regulator, a band gap reference, and a PLL to provide an analog front-end for automotive audio applications. The ADC inputs accept 4.5 V rms, fully differential, ac-coupled signals. The multibit, continuous-time sigma-delta architecture achieves low EMI, 109-dB dynamic range, and –95-dB THD+N. The on-chip PLL, which can derive the master clock from an external clock or frame clock, eliminates the need for a separate high-frequency master clock. Operating on 1.8-V and 3.3-V supplies, the ADAU1979 dissipates 56 mW in normal mode and 1 mW in power-down mode. Available in a 40-lead LFCSP package, it is specified from –40°C to +105°C and priced at $4.06 in 1000s.
Four-string white LED Driver for LCD backlight applications
The ADD5211 white-LED driver uses a high-efficiency, current-mode step-up converter to provide four regulated constant-current sources—each capable of driving 40 mA to 200 mA—to illuminate four strings of series-connected LEDs in backlight applications. The LED current is set by an external resistor and the 0.45% current matching ensures uniform LED brightness. The boost controller operates with a 200-kHz to 1.2-MHz switching frequency. An adjustable UVLO function reduces input current during power down. Additional features include LED short protection, LED open protection, boost output short protection, overvoltage protection, cycle-by-cycle current limit, and thermal shutdown for both the IC and the LED array. An open-drain fault output is also included. Programmable soft start reduces inrush current during startup. Operating with a 4.5-V to 40-V supply, the ADD5211 draws 2.8 mA in normal mode and 1 µA in shutdown mode. Specified from –40°C to +125°C, it is available in a 24-lead LFCSP package and priced at $1.40 in 1000s.
10-Bit, 4× Oversampled SDTV Video Decoders
The ADV7280, ADV7280-M, ADV7281-M, ADV7281-MA, and ADV7282-M versatile single-chip, multiformat video decoders automatically detect standard analog baseband video signals compatible with worldwide NTSC, PAL, and SECAM standards in the form of composite, S-Video, and component video, and convert them into 8-bit video data streams. The video decoders are programmed via a 2-wire, I2C-compatible serial interface. Operating with 1.8-V and 3.3-V supplies, they draw 315 mW in normal mode and 1 mW in power-down mode. Qualified for automotive applications, they are specified from –40°C to +105°C, available in 32-lead LFCSP packages, and priced from $3.65 in 1000s. Additional features are specified in the table.
500-mA High-Side Load Switch Integrated with Quad Signal Switch
The ADP1190A integrated high-side load switch with four signal switches provides power domain isolation for extended battery life, disconnecting SIM cards and data cards in handsets, tablets and USB dongles. The low on-resistance P-channel MOSFET load switches support up to 500 mA of continuous load current and minimize power loss. Also integrated are four normally open 3-Ω SPST signal switches. Operating on a single 1.4-V to 3.6-V supply, the ADP1190A draws 2 µA max. Available in a 12-ball, 0.4-mm pitch WLCSP, the ADP1190A has lower switch capacitance and a thinner package than the original ADP1190. It is specified from –40°C to +85°C and priced at $0.60 in 1000s.
High-performance 12-/16-channel, 24-bit, 192-kHz Differential-Output DACs
The ADAU1962A and ADAU1966A high-performance digital audio circuits comprise 12/16 multibit Σ-Δ DACs with single-ended or differential outputs, plus digital filters and volume controls. The DACs provide 114-dB dynamic range and –97-dB total harmonic distortion plus noise (THD+N) in differential mode. A microcontroller can adjust volume and other parameters, and read the temperature of the on-chip temperature sensor, via an SPI/I2C port. For low EMI, the on-chip PLL derives the master clock from an external left/right frame clock—eliminating the need for a separate high-frequency master clock and allowing the DACs to be used with or without a bit clock. The continuous-time architecture and low-voltage operation combine to further minimize EMI, power consumption, and digital waveform amplitudes. The ADAU1962AW/66AW use two separate power sources or a single analog supply with an on-chip regulator producing the digital supply. Operating with a 2.25-V to 3.46-V digital supply and 3.14-V to 3.46-V analog supply, they consume 299 mW in normal mode and 15 µW in power-down mode. Available in 80-lead LQFP packages, they are specified from –40°C to +105°C, release to automotive (RTA) qualified, and priced at $5.08/$6.34 in 1000s.
Michael Corrigan & Joe Triggs, CRC testing in video applications, EDN, 2013-09-10
Jeff Ugalde, Ian Beavers, and Lie Dou, Deliver Quad-HD Video Over HDMI Cables, Electronic Design, 2013-03-05
Witold Kaczurba and Brett Li, HDMI Made Easy: HDMI-to-VGA and VGA-to-HDMI Converters, Analog Dialogue, 2013-02-04
Jerad Lewis and Paul Schreier, Low self noise: The first step to high-performance MEMS microphone applications, EE Times, 2012-11-28
Brett Li and Li Dou, HDMI I/O Solution and Reference Design, Global Electronics China, 2012-09-19
Jerad Lewis, Understanding Microphone Sensitivity, Analog Dialogue, 2012-05-01
Javier Calpe, Italo Medina, Alberto Carbajo, and María José Martínez, AD7879 Controller Enables Gesture Recognition on Resistive Touch Screens, Frontier Journal, 2012-05-01
What is a "Wide Dynamic Range" Microphone and why does it matter to my design? - MEMS microphones with the capability to capture very high sound pressure acoustic waves (loud noises) with high fidelity hold the potential to improve user experience in audio capture and to make acoustic detection viable for a range of applications that might have previously been unsuitable for such methods. We'll discuss design considerations for these microphones and applications that might benefit from such high performance.
Copyright 1995- Analog Devices, Inc. All rights reserved.