SA5753 Datasheet, PDF (5/15 Pages) NXP Semiconductors – Audio processor - filter and control section

Philips Semiconductors
Audio processor – filter and control section
Product specification
SA5753
AC ELECTRICAL CHARACTERISTICS (continued)
SYMBOL
PARAMETER
LIMITS
TEST CONDITIONS
UNIT
MIN
TYP
MAX
TX overall gain
3kHz
8
9
9.6
dBm0
TX overall gain
5.9kHz
-52
-45
dBm0
TX BPF dynamic range
TBD
dB
PREMP_IN input impedance
TX_OUT Slew rate
Output impedance
f = 3kHz
C_L = 15pF
f = 3kHz
100
kΩ
0.75
V/µs
40
Ω
Output swing (limiting)
Output swing (1% THD)
Tx DTMF signal with TXLPF and pre-emphasis
5kΩ load (25°C)
1.2
1.0
0.45
V_P-P
V_P-P
V/kHz
Rx DTMF sidetone
–0.8
5.2
dBm0
Time delay to mute from RX MUTE or TX MUTE
transition
V_IN = V_IL to V_IH
V_IN = V_IH to V_IL
0.5
µs
0.5
µs
Table 1. Gain Control Blocks (Bit 0 is Least Significant Bit)
SYMBOL
Bits
TYPICAL STEP (dB)
A1
A2a
A2b
A3
A4
A6
A7
NAMPS
VCO
For A2a, A4 and A7:
For all Gain Blocks:
4
–0.8
5
±0.25
2
–6, (–12 on first)
4
–1.0
4
±0.5
4
–2.0
4
±0.5
1
1
MSB sets the sign of the gain
MSB = 0 for gain
MSB = 1 for attenuation
All bits set to 0 = 0dB gain
All bits set to 1 = maximum gain or attenuation
TYPICAL GAIN (dB)
MIN
MAX
–12.0
0
–3.75
+3.75
–24.0
0
–17.0
–2.0
–3.5
+3.5
–30.0
0
–3.5
+3.5
+1.9 in A2b
–7.6 in A4
+6.0 in A4
FUNCTIONAL DESCRIPTION
The SA5753 is an audio signal processor designed to meet the
requirements of compact low voltage radio telephone equipment. It
includes transmit and receive bandpass filters for voiceband
(300-3000Hz) with pre-emphasis and de-emphasis respectively, a
transmit peak deviation limiter, voice channel mute switches and a
data path which can be summed into the transmit channel. An I²C
interface is provided for software programmability of a DTMF
generator, mute polarity, selection of different power down and
operating modes and control of the gain in both the transmit and
receive channels.
Software programmable gain control allows the device to be
automatically optimized during equipment production and offers
flexibility during normal operation.
Gain Blocks
The programmable gain blocks are shown in Table 1 and Figure 2.
The purpose for each block is as follows:
a. A1 compensates for microphone gain variations in the transmit
path.
b. A2a compensates for transmitter dynamic range variations due to
manufacturing tolerances of the SA5753 and SA5752 compandor
companion device. To meet AMPS requirements, the dynamic
range between the zero crossing signal level of the compandor
and the peak signal allowed by the deviation limiter is adjusted to
12.34dB.
c. A2b allows coarse attenuation to be inserted in the transmit path
to eliminate positive feedback effects in hands-free speaker
applications. First step is 12dB followed by two steps of 6dB.
d. A3 sets the gain between the DATA_IN pin (Pin 19) and the TX_OUT
pin (Pin 20) and should be adjusted after A2a and A4 have been
previously optimized. The SA5753 will interface directly with the
UMA1000T data processor (which produces a 2Vpk data signal).
For NAMPS applications an additional 10 to 14dB resistive divider
must be added at the DATA_IN pin (Pin 19) for a 2V data signal.
1997 Nov 07
5