TDA9852 データシートの表示（PDF） - Philips Electronics

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TDA9852

I2C-bus controlled BTSC stereo/SAP decoder and audio processor

Philips Electronics 

Philips Semiconductors

I2C-bus controlled BTSC stereo/SAP

decoder and audio processor

Preliminary specification

TDA9852

MUTE

The mute function can be activated independently with last

step of volume control at the left or right output. By setting

the general mute bit GMU via the I2C-bus all outputs are

muted. All channels include an independent zero cross

detector. The zero crossing mute feature can be selected

via bit TZCM:

TZCM = 0: forced mute with direct execution

TZCM = 1: execution in time with signal zero crossing.

In the zero cross mode a change in the GMU polarity is

activated but not executed. The execution is enabled at

the next zero crossing of the signal. To avoid a large delay

of mute switching, when very low frequencies are

processed, or the output signal amplitude is lower than the

DC offset voltage, the following I2C-bus transmissions are

needed:

a first transmission for mute execution

a second transmission about 100 ms later, which must

switch the zero crossing mode to forced mute

(TZCM = 0)

a third transmission to reactivate the zero crossing

mode (TZCM = 1). This transmission can take place

immediately, but must follow before the next mute

execution.

Adjustment procedure

COMPOSITE INPUT LEVEL ADJUSTMENT

Feed in from FM demodulator the composite signal with

100% modulation (25 kHz deviation) L + R; fi = 300 Hz.

Set input level control via I2C-bus monitoring line out

(500 mV ±20 mV). Store the setting in a non-volatile

memory.

AUTOMATIC ADJUSTMENT PROCEDURE

• Capacitors of external inputs LIL and LIR must be

grounded at EIL and EIR

• Composite input signal L = 300 Hz, R = 3.1 kHz,

14% modulation for each channel; volume gain +16 dB

via I2C-bus

• Effects, AVL, loudness off.

• Line out setting bits: STEREO = 1, SAP = 0

(see Table 12)

• Selector setting SC0, SC1, SC2 = 0, 0, 0 (see Table 11)

• Start adjustment by transmission ADJ = 1 in register

ALI3; the decoder will align itself

• After 1 second minimum stop alignment by transmitting

ADJ = 0 in register ALI3 read the alignment data by an

I2C-bus read operation from ALR1 and ALR2

(see Chapter “I2C-bus protocol”) and store it in a

non-volatile memory; the alignment procedure

overwrites the previous data stored in ALI1 and ALI2

• Disconnect the capacitors of external inputs from

ground.

MANUAL ADJUSTMENT

Manual adjustment is necessary when no dual tone

generator is available (e.g. for service).

• Spectral and wideband data have to be set to 10000

(middle position for adjustment range)

• Composite input L = 300 Hz; 14% modulation

• Adjust channel separation by varying wideband data

• Composite input L = 3 kHz; 14% modulation

• Adjust channel separation by varying spectral data

• Iterative spectral/wideband operation for optimum

adjustment

• Store data in non-volatile memory.

TIMING CURRENT FOR RELEASE RATE

Due to possible internal and external spreading, the timing

current can be adjusted via I2C-bus, see Table 20, as

recommended by dbx.

1997 Mar 11

10

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