ATR4256 – Frequency Synthesizer

Part Number : ATR4256

Function : Frequency Synthesizer

Manufactures : ATMEL Corporation

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ATR4256 image

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Description :

Features Reference Oscillator up to 15 MHz (Tuned) Oscillator Buffer Output (for AM Up/Down Conversion) Two Programmable 16-bit Dividers Fine-tuning Steps Possible Fast Response Time Due to Integrated Loop Push-pull Stage 3-wire Bus (Enable, Clock and Data; 3V and 5V Microcontrollers Acceptable) Four Programmable Switching Outputs (Open Drain) Three DACs for Software Controlled Tuner Alignment Low-power Consumption High Signal to Noise Ratio (SNR) Integrated Band Gap – Only One Supply Voltage Necessary 1. Description The ATR4256 is a synthesizer IC for FM receivers and an AM up-conversion system in BiCMOS technology. Together with the AM/FM IC ATR4258 or ATR4255, it comprises a complete AM/FM car radio front-end, which is also recommended for RDS (Radio Data System) applications. It is controlled by a 3-wire bus and also contains switches and Digital to Analog Converters (DACs) for software-controlled alignment of the AM/FM tuner. The ATR4256 is the pin-compatible successor IC of U4256BM-R. Figure 1-1. Block Diagram SWO1 SWO2 SWO3 SWO4 7 Tuning 13 12 Oscillator Switching outputs DAC3 3-bit V Ref DAC2 3-wire bus interface 4 5 8 9 10 Frequency Synthesizer for Radio Tuning ATR4256 OSCIN OSCOUT DAC3 MX2LO 15 OSC buffer CLK DATA EN 17 16 18 DAC2 DAC1 3 DAC1 Rdivider DAC AM/FM VRef FMOSCIN 19 FMpreamp Ndivider Phase detector Current sources 1 PDO Band gap 20 GNDAN V5 14 11 GND VS 6 2 PD 4867D–AUDR–01/08 2. Pin Configuration Figure 2-1. Pinning SSO20 FMOSCIN OSCOUT 12 SWO3 9 GNDAN MX2LO OSCIN DATA CLK 20 19 18 17 16 15 ATR4256 14 13 Table 2-1. Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Pin Description Symbol PDO PD DAC1 DAC2 DAC3 VS SWO1 SWO2 SWO3 SWO4 GND OSCOUT OSCIN V5 MX2LO DATA CLK EN FMOSCIN GNDAN Function Phase detector output Pulsed current output Digital-to-analog converter 1 Digital-to-analog converter 2 Digital-to-analog converter 3 Supply voltage, analog part Switching output 1 Switching output 2 Switching output 3 Switching output 4 Ground, digital part Reference oscillator output Reference oscillator input Capacitor band gap Oscillator buffer output Data input Clock Enable FM-oscillator input Ground, analog part 2 ATR4256 4867D–AUDR–01/08 SWO2 DAC1 DAC3 SWO4 10 1 4 5 2 3 6 DAC2 SWO1 PDO PD VS 7 8 11 GND EN V5 ATR4256 3. Functional Description For a tuned FM-broadcast receiver, the following parts are needed: • Voltage-controlled Oscillator (VCO) • Antenna Amplifier Tuned Circuit • RF Amplifier Tuned Circuit Typical modern receivers with electronic tuning are tuned to the desired FM frequency by the frequency synthesizer IC ATR4256. The special design allows the user to build software-controlled tuner alignment systems. Two programmable DACs (Digital-to-Analog Converter) support the computer-controlled alignment. The output of the PLL is a tuni […]

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ATR4256 Datasheet


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