ST5088
Current limitation is approximatively 150 mApk.
CONTROL REGISTER CR7:
First byte of a READ or a WRITE instruction to
Control Register CR7 is as shown in TABLE 1.
Second byte is as shown in TABLE 9.
Tone/Ring amplifier gain selection
Output level of Ring/Tone generator, before at-
tenuation by programmable attenuator is 2.4 Vpk-
pk when f1 generator is selected alone or
summed with the f2 generator and 1.9 Vpk-pk
when f2 generator is selected alone.
Selected output level can be attenuated down to
-27 dB by programmable attenutator by setting
bits 4 to 7.
Frequency mode selection
Bits ’F1’ (3) and ’F2’ (2) permit selection of f1
and/or f2 frequency generator according to TA-
BLE 9.
When f1 (or f2) is selected, output of the
Ring/Tone is a squarewave (or a sinewave) signal
at the frequency selected in the CR8 (or CR9)
Register.
When f1 and f2 are selected in summed mode,
output of the Ring/Tone generator is a signal
where f1 and f2 frequency are summed.
In order to meet DTMF specifications, f2 output
level is attenuated by 2dB relative to the f1 output
level.
Frequency temporization must be controlled by the
microcontroller.
Any switching between two frequencies of the
same channel (f1 or f2) is done maintaining prac-
tically the phase continuity.
The actual change in the frequency of the tone
generator takes place within 1/16th of the period
of the highest of the two frequencies that are
switched between, plus 2µs for internal data ac-
quisition.
Waveform selection
Bit ’SN’ (1) selects waveform of the output of the
Ring/Tone generator. Sinewave or squarewave
signal can be selected.
DTMF selection
Bit DE (0) permits connection of Ring/Tone/DTMF
generator on the Transmit Data path instead of
the Transmit Amplifier output. Earpiece feed-back
may be provided by sidetone circuitry by setting
bit SI or directly by setting bit RTE in Register
CR4. Loudspeaker feed-back may be provided di-
rectly by setting bit RTL in Register CR4.
CONTROL REGISTERS CR8 AND CR9
First byte of a READ or a WRITE instruction to
20/33
Control Register CR8 or CR9 is as shown in TA-
BLE 1. Second byte is respectively as shown in
TABLE 10 and 11.
Tone or Ring signal frequency value is defined by
the formula:
f1 = CR8 / 0.128 Hz and f2 = CR9 / 0.128 Hz
(with DFT = HFT = 0 in CR10)
where CR8 and CR9 are decimal equivalents of
the binary values of the CR8 and CR9 registers
respectively. Thus, any frequency between 7.8 Hz
and 1992 Hz may be selected in 7.8 Hz step.
TABLE 13 gives examples for the main frequen-
cies usual for Tone or Ring generation.
CONTROL REGISTER CR10
First byte of a READ or a WRITE instruction to
control register CR10 is as shown in TABLE 1.
Second byte is as shown in Table 12.
Extra +18dB in LS Gain
GLS = 1 sets extra 18dB Gain (total Gain = 27dB)
GLS = 0 sets standard Gain = 9dB like on ST5080
Anticlipping enable, thresholds and time con-
stants
ACE = 1 enables the operation of the Digital anti-
clipping section (D.A.S.), needed to avoid distor-
tion on sine wave when GLS = 1 (extra 18dB on LS)
anticlipping thresholdsof -15, -13, -9 and -7dBmo are
definedby bits 4 and 5 (VT1/VT0).
Gain recovery the constants (anticlipping release)
are selectable among four values, 256ms, 128ms,
32ms and 16ms by bits 2 and 3 (FD1/FD0).
Doubled Tone/Ringer Frequency Range
Double frequency range on tone & ringer gener-
ator is obtainedby putting DFT = 1 (and HFT = 0).
Formula for frequency generator is:
f1 = CR8/0.064Hz and f2 = CR9/0.064Hz.
Maximum frequency is 3984.4Hz and frequency
accuracy is 15.6Hz.
Halved Tone/Ringer Frequency Range
Halved frequency and double accuracy on tone &
ringer generator is obtained bu putting HFT = 1 (and
DFT = 0).
Formula for frequency generator is:
f1 = CR8/0.256Hz and f1 = CR9/0.256Hz
Frequency range is from 3.9Hz to 996.1Hz and
step is 3.9Hz with improved accuracy for low fre-
quencies combination.
HFT = DFT= 1 is a forbidden combination.