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TDA18271HD

Silicon Tuner IC

NXP Semiconductors. 

NXP Semiconductors

TDA18271HD

Silicon Tuner IC

8.3 Tuner outputs

The tuner provides a slave tuner output (pin STO) and a loop-through output (pin LT).

These outputs are used to transmit the antenna signal to other tuners. Each output has its

own characteristics (see Table 58 and Table 59).

8.3.1 Loop-through output

The gain between the antenna connector and the loop-through pin (pin LT) equals 0 dB.

This pin can be connected to any consumer electronic equipment.

8.3.2 Slave tuner output

In dual tuner applications the slave tuner output (pin STO) must be connected to the RF

input of the slave tuner TDA18271HD.

The gain between the antenna connector and the slave tuner output can change

according to the input level. The slave tuner will automatically compensate for the gain

change, using the MASTERSYNC and FREEZE signals.

8.4 Crystal input mode

The TDA18271HD requires a 16 MHz crystal reference. The chosen crystal must

withstand at least 100 µW drive level and an additional shunt capacitor with a typical value

of 5.6 pF as shown in Figure 1 is also needed. The quartz references for which the

performances are guaranteed are:

• NDK NX5032

• Siward SX-5032

• TXC 9C series

• Chungho Elcom HC49S profile

Clock reference:

• In Master mode, the clock reference must be provided by a 16 MHz crystal connected

between pins XTALP and XTALN of the master tuner

• In Slave mode, the clock reference must be provided by pins XTOUTP and XTOUTN

of the tuner in Master mode to pins XTALP and XTALN of the tuner in Slave mode

8.5 Crystal output mode

Pins XTOUTP and XTOUTN deliver a symmetrical sine waveform to drive the channel

decoder and/or IF demodulator. The load on these outputs should be made similar to

ensure optimum performances. If only one crystal output is used, the unused output

should be loaded by an equivalent capacitance.

TDA18271HD_4

Product data sheet

Rev. 04 — 19 May 2009

© NXP B.V. 2009. All rights reserved.

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