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TDA18271HD

Silicon Tuner IC

NXP Semiconductors. 

NXP Semiconductors

TDA18271HD

Silicon Tuner IC

8. Functional description

The RF input signal is driven to a low-noise amplifier. It is then band-pass filtered,

amplified and fed to the image rejection mixer. The mixer downconverts the RF signal to a

low IF depending on the channel bandwidth.

Standard IF filters are implemented for 1.5 MHz, 6 MHz, 7 MHz and 8 MHz channel

bandwidths; see Table 43.

The Silicon Tuner can be used either as TV receiver or FM radio receiver.

The TDA18271HD requires a single 16 MHz crystal for clock generation. When bit

XTOUT_ON = 1, a clock signal is available on pins XTOUTP and XTOUTN to drive a

second tuner, a channel decoder or an IF demodulator (TDA8295) for analog TV reception

and FM radio.

Remark: Most recent video decoders from NXP Semiconductors include a low IF

demodulation function.

8.1 TV and FM reception

The Silicon Tuner can be used in two modes, selectable via the I2C-bus:

• TV reception: the RF signal must be connected to pin RF_IN

• FM reception: the RF signal must be connected to pin FM_IN or RF_IN

The RF_IN input pin can also be used for FM reception at the cost of software

modification. The FM_IN input pin can only receive signals in the FM frequency range.

8.2 Master and slave operation

The TDA18271HD allows easy dual-tuner configuration.

Each individual tuner has to be set either to Master mode or Slave mode by applying a

specific DC voltage to the XTOUT_MS pin; see Table 4. This will decide whether the

crystal oscillator part is used as negative impedance connected to the crystal part or as a

current buffer.

Table 4. Master/slave selection

Voltage on pin XTOUT_MS Tuner type

0 V to 0.1VCC

0.4VCC to 0.6VCC

master

slave

In dual tuner applications:

Crystal oscillator function

negative impedance presented to the crystal

current input buffer

• The first tuner is set to Master mode

• The second tuner has to be set to Slave mode

In single tuner applications:

• The tuner must be set to Master mode

TDA18271HD_4

Product data sheet

Rev. 04 — 19 May 2009

© NXP B.V. 2009. All rights reserved.

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