300MHz to 450MHz ASK Transmitter Supports Two Operating Frequencies with One Crystal
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Dual-Frequency Transmitter Maximizes Operating-Frequency Flexibility
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Note to Editor:
- The MAX7058 is a crystal-referenced, phased-locked loop VHF/UHF transmitter for transmitting OOK/ASK data at 315MHz or 390MHz.
- This device supports two operating frequencies with a single reference crystal.
- To enable this flexibility, the MAX7058 integrates a wideband VCO and internal tuning capacitors that can be programmed to match the impedance of the power amplifier to the antenna.
- The MAX7058 is ideal for power-sensitive applications such as home security systems, remote controls, and garage door openers.
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SUNNYVALE, CA—May 29, 2008—Maxim Integrated Products (PINK OTC MARKETS: MXIM) introduces the MAX7058 crystal-referenced, phased-locked loop (PLL) VHF/UHF transmitter for transmitting OOK/ASK/FSK data at 315MHz or 390MHz. This device supports 315MHz/390MHz switched operation with a single 15MHz crystal, and can operate at any two frequencies in the 300MHz to 450MHz range with the use of different crystal frequencies. To enable this flexibility, the MAX7058 integrates a wideband VCO with internal tuning capacitors that can be programmed for matching the impedance of the power amplifier (PA) to the antenna. This topology ensures highly efficient transmission at multiple operating frequencies, thus making the MAX7058 ideal for power-sensitive applications such as home security systems, remote controls, and garage door openers.
To further improve performance, the MAX7058 integrates an envelope-shaping resistor between the output of the PA and the power supply. This resistor slows the turn-on/off time of the PA in ASK mode, reducing the spectral width of the PA's modulated output signal. Additionally, the MAX7058 features a toggle pin that allows the device to switch automatically between two frequencies, thus eliminating the need for a microprocessor or switch.
The MAX7058's crystal-based architecture eliminates many common SAW transmitter problems by providing greater modulation depth, faster frequency settling, tighter transmit-frequency tolerance, and reduced temperature dependence. This device thus provides better overall receiver performance when using a superheterodyne receiver with a narrow IF (i.e., lower noise) bandwidth.
The MAX7058 operates from a single, 2.1V to 3.6V supply, and draws less than 1µA in standby mode and less than 8mA in transmit mode (50% duty cycle OOK). Available in a small, 4mm x 4mm, 24-pin TQFN package, this device is fully specified over the -40° to +125° automotive temperature range. Prices start at $1.32 (1000-up, FOB USA).
Maxim Integrated Products is a publicly traded company that designs, manufactures, and sells over $2 billion of high-performance semiconductor products annually. It was founded over 25 years ago with the mission to deliver innovative analog and mixed-signal engineering solutions that add value to its customers' products. To date, Maxim has developed over 5700 products serving the industrial, communications, consumer, and computing markets. For more information, go to www.maxim-ic.com.
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