TDA8745 Datasheet, PDF (18/40 Pages) NXP Semiconductors – Satellite sound receiver with I2C-bus control

Philips Semiconductors
Satellite sound receiver with I²C-bus control
Preliminary specification
TDA8745
Table 19 Bits DEM1 and DEM0; De-emphasis; note 1;
see Fig.5
DEM1
a2
0
0
1
1
DEM0
a1
0
1
0
1
DE-EMPHASIS
no de-emphasis (flat)
J17
50 µs⁽²⁾
75 µs [por]⁽³⁾
Notes
1. Different de-emphasis characteristics can be selected,
to adjust for different main channel audio carriers.
2. In most cases the de-emphasis needed for main
channel carriers is 50 µs.
3. The NR is to be used with the 75 µs setting for
standard secondary channels.
Table 20 Bit BPFN; Band-Pass Filter Not; note 1
BPFN
a0
0
1
DESCRIPTION
mixer input signal filtered by BPF
(after POR)
mixer input signal is not filtered
Note
1. To avoid interference by the video signal, the incoming
baseband signal is filtered. If this filtering is not
required the filter can be switched off.
Slave transmitter mode (bits transmitted from
TDA8745 to microcontroller)
Table 21 Bit PDL; Presence Detector Left; note 1
PDL
r7
0
1
DESCRIPTION
carrier detected at left channel
no carrier detected at left channel
Note
1. Bit PDL (r7) transmits the current status of the left
channel presence detector. When PDL = 1, no carrier
is found at the currently selected frequency. If bit
PDM (s3) = 0 the left channel audio is muted.
Table 22 Bit PDR; Presence Detector Right; note 1
PDR
r6
0
1
DESCRIPTION
carrier detected at right channel
no carrier detected at right channel
Note
1. Bit PDR (r6) transmits the current status of the right
channel presence detector. When PDR = 1, no carrier
is found at the currently selected frequency. If bit
PDM (s3) = 0 the right channel audio is muted.
Table 23 Bit POR; Power-On Reset; note 1
POR
r0
0
1
DESCRIPTION
normal operation
POR generated; power dip detected since last read of POR bit
Note
1. At switching on, or after a power dip on the I²C-bus supply voltage (V_P2), an internal signal is generated which resets
the I²C-bus registers to a pre-defined state. If bit POR (r0) = 1, such a situation has occurred since the last time the
read byte was read. After reading, the bit is reset to logic 0.
Table 24 Bits r5 to r1
−
−
−
−
−
r5
r4
r3
r2
r1
DESCRIPTION
1
1
1
1
1 These bits have no function. Although their state is fixed, the microcontroller
should not rely on this because of eventual future use.
1996 Mar 11
18