Features: · Direct conversion Quadrature Phase Shift Keying (QPSK) and 8-Phase Shift Keying (8PSK) demodulation (Zero-IF)· Frequency range: 950 to 2175 MHz· High level asymmetrical RF input· 0 to 50 dB variable gain with AGC control· Loop-controlled 0 to 90° phase shifter· High AGC linearity (<...
TDA8260TW: Features: · Direct conversion Quadrature Phase Shift Keying (QPSK) and 8-Phase Shift Keying (8PSK) demodulation (Zero-IF)· Frequency range: 950 to 2175 MHz· High level asymmetrical RF input· 0 to 50...
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SYMBOL | PARAMETER | MIN. | MAX. | UNIT |
VCC | supply voltage | -0.3 | +6.0 | V |
Vi(max); Vo(max) | maximum input or output voltage on all pins except SDA, SCL and VT | -0.3 | VCC + 0.3 | V |
Vi(SDA); Vo(SDA) | data input or data output voltage | -0.3 | +6.0 | V |
Vi(SCL) | clock input voltage | -0.3 | +6.0 | V |
Vo(tune) | tuning voltage output | -0.3 | +35 | V |
Tamb | ambient temperature | -20 | +85 | °C |
Tstg | IC storage temperature | -40 | +150 | °C |
Tj(max) | maximum junction temperature | - | 150 | °C |
tsc(max) | maximum short-circuit time; each pin; short-circuit to VCC or GND | - | 10 | S |
The direct conversion QPSK demodulator TDA8260TW is the front-end receiver dedicated to digital TV broadcasting, satisfying both DVB and DBS TV standards. The wide range oscillator (from 950 to 2175 MHz) covers the American, European and Asian satellite bands, as well as the SMA-TV US standard.
The Zero-IF concept discards traditional IF filtering and intermediate conversion techniques. It also simplifies the signal path.
TDA8260TW Optimum signal level is guaranteed by gain-controlled amplifiers in the RF path. The 0 to 50 dB variable gain is controlled by the signal returned from the Satellite Demodulator and Decoder (SDD) and applied to pin AGCIN.
The PLL synthesizer is built on a dual-loop concept. The first loop controls a fully integrated L-band oscillator, using as a reference the LC VCO which runs at a quarter of the synthesized frequency.
The second loop controls the tuning voltage of the VCO and improves the phase noise of the carrier within the loop bandwidth. The step size is equal to the comparison
requency. The input of the main divider of the PLL synthesizer is connected internally to the VCO output.
The comparison frequency of the TDA8260TW second loop is obtained from an oscillator driven by an external 4 MHz crystal. The 4 MHz output available at pin XTOUT may be used to drive the crystal inputs of the SDD, thereby saving an additional crystal in the application.
Both the divided and the comparison frequencies of the second loop are compared in a fast phase detector which drives the charge pump. The TDA8260TW includes a loop amplifier with an internal high-voltage transistor to drive an external 33 V tuning voltage.
Control data is entered via the I2C-bus. The I2C-bus voltage can be 5.0, 3.3 or 2.5 V, thus allowing compatibility with most existing microcontrollers.
A 5-byte frame is required to address the device and to program the main divider ratio, the reference divider ratio, the charge pump current and the operating mode.
A flag is set when the loop is 'in-lock', this can be read during READ operations, as well as the Power-on reset flag.
The device has four selectable I2C-bus addresses. The selection is done by applying a specific voltage to pin AS. This feature gives the possibility to use up to four TDA8260TW ICs in the same system.