Direct-Conversion TV Tuner

14

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Shutdown Control (Register Address 0x08)

SHDN_BG: Main Bandgap

0 = Enabled

1 = Disabled

The main bandgap can and will be shut down

once all other blocks are shut down (i.e., all bits in this

shutdown register and bits VCO_ in the VCO

Control Register and bits DC_MO_ in the DC

Offset Control Register are shut down).

SHDN_PD: Baseband Power Detector

0 = Enabled

1 = Disabled

SHDN_RF: RF LNA/VGA:

0 = Enabled

1 = Disabled

SHDN_MIX: I/Q Mixer and LO Drivers

0 = Enabled

1 = Disabled

SHDN_BB: Baseband Filters and VGA

0 = Enabled

1 = Disabled

SHDN_SYN: Fractional PLL

0 = Enabled

1 = Disabled

SHDN_REF: Controls the Crystal Oscillator Buffered

Output

0 = Enabled

1 = Disabled

The XTAL oscillator activation results from the

SHDN_SYN, SHDN_REF bits: If either one is on,

the XTAL oscillator runs. The XTAL oscillator is

shut down only if both bits are off.

VCO Control (Register Address 0x09)

VCO<1:0>: Selects 1 of 3 VCO Bands. 00 turns off

VCO block completely.

BS<2:0>: Selects 1 of 8 VCO Sub-Bands

VAS: VCO Band Autoselect

0 = VCO band select controlled by bits VCO<1:0>

1 = Controlled by autotuner

ADL: VCO ADC Latch Enable Bit

1 = Latches ADC value

0 = Default

ADE: Enable VCO Tune Voltage DAC Read

1 = Enables ADC read

0 = Default

Baseband Control (Register Address 0x0A)

PD_TH<2:0>: Detection Threshold for Baseband

Power Detector

BB_BW<3:0>: Baseband Filter Bandwidth. Optimum

values for 7MHz and 8MHz wide RF channels can

be taken from the ROM table.

DC Offset Control (Register Address 0x0B)

DC_TH<1:0>: DC Offset Correction Thresholds.

Keeps output within:

00 = Output within ±0.55V of balanced state

11 = Output within ±0.75V of balanced state

DC_SP<1:0>: DC Offset Correction Speed (or Highpass

Corner Frequency).

11 = Fast (~500Hz)

01 = Slow (~20Hz)

00 = Off/hold DAC values

DC_MO<1:0>: Mode of Operation

00 = Off

10/01 = Sets I/Q channel DACs direct from register

11 = Normal operation

DC_DAC<8>: MSB for DC Offset DAC

BB_BIA: Baseband Filter Op-Amp Bias Settings

0 = Low

1 = High

*

Not production tested.