Part Number : ATR4256
Function : Frequency Synthesizer for Radio Tuning
Package : SSOP 20 Pin type
Manufactures : ATMEL Corporation
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.
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 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 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
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 […]