TDA9874AHB View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
'TDA9874AHB' PDF : 69 Pages View PDF
Philips Semiconductors
Digital TV sound demodulator/decoder
Product specification
TDA9874A
7 I2C-BUS CONTROL
7.1 Introduction
The TDA9874A is controlled only via the I2C-bus. Control
is exercised by writing data to one or more internal
registers. Status information can be read from an array of
registers to let the controlling microprocessor determine
whether any action is required.
The device has an I2C-bus slave transceiver in
accordance with the fast-mode specification with a
maximum speed of 400 kbits/s. Information about the
I2C-bus can be found in brochure “I2C-bus and how to use
it” (order number 9398 393 40011). To avoid conflicts in a
real application with other ICs providing similar or
complementing functions, there are four possible slave
addresses available, which can be selected by
pins ADDR1 and ADDR2 (see Table 6).
Table 6 Possible slave addresses
SLAVE ADDRESS
ADDR2 ADDR1
A6 A5 A4 A3 A2 A1 A0
0
0
1011000
0
1
1011001
1
0
1011010
1
1
1011011
The I2C-bus interface remains operational in the standby
mode of the TDA9874A to allow the device to be
reactivated via the I2C-bus.
The device will not respond to a ‘general call’ on the
I2C-bus, i.e. when a slave address of 0000 000 is sent by
a master.
7.2 Power-up state
After Power-on reset respectively at power-up the device
is in the following state:
• All outputs muted
• No sound carrier frequency loaded
• General purpose I/O pins ready for input (HIGH)
• Input SIF1 selected with:
– AGC on
– SIF 10 dB attenuator off
– Small hysteresis.
• Demodulators for both sound carriers set to FM with:
– Identification for B/G, D/K, identification mode ‘slow’
– Level adjustment set to 0 dB
– De-emphasis 50 µs
– Dematrix set to mono
– Adaptive de-emphasis off.
• Analog outputs are muted and connected to DACs
• Digital audio interface all outputs off
• Monitor set to carrier 1 DC output.
After Power-on reset or power-up, a device initialization
has to be performed via the I2C-bus to put the TDA9874A
into the proper mode of operation, in accordance with the
desired TV standard, etc. This can be done by writing to all
registers with a single I2C-bus transmission (such as a
refresh operation) or by writing selectively only to those
registers, the contents of which need to be changed with
regard to the power-up state. Easy Standard Programming
(ESP) can also be used.
2000 Aug 04
16
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