ST5090AD datasheet(15/29 Pages) STMICROELECTRONICS

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Tone/Ring amplifier gain selection

Output level of Ring/Tone generator, before at-

tenuation by programmable attenuator is 1.6 Vpk-

pk when f1 generator is selected alone or

summed with the f2 generator and 1.26 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)

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.

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 or extra

receive output 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 directly by setting bit

RTL in Register CR4.

CONTROL REGISTERS CR8 AND CR9

First byte of a READ or a WRITE instruction to

Control Register CR8 or CR9 is as shown in TA-

BLE 1. Second byte is respectively as shown in

TABLE 10 and 11.

If ”standard frequency tone range” is selected,

Tone or Ring signal frequency value is defined by

the formula:

f1 = CR8 / 0.128 Hz

and

f2 = CR9 / 0.128 Hz

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.

If ”halved frequency tone range”is selected, Tone

or Ring signal frequency value is defined by the

formula:

f1 = CR8 / 0.256 Hz

and

f2 = CR9 / 0.256 Hz

This any frequency between 3.9Hz and 996Hz

may be selected in 3.9Hz step.

If ”doubled frequency tone range”is selected,

Tone or Ring signal frequency value is defined by

the formula:

f1 = CR8 / 0.064 Hz

and

f2 = CR9 / 0.064 Hz

Thus any frequency between 15.6Hz and 3984Hz

may be selected in 15.6Hz step.

TABLE 12 gives examples for the main frequen-

cies usual for Tone or Ring generation.

CONTROL REGISTER CR10

Bit DFT(1) and HFT(0) permits the selection

among ”standard frequency tone range” (i.e. from

7.8Hz to 1992Hz in 7.8Hz step), ”halved fre-

quency tone range” (i.e. from 3.9Hz to 996Hz in

3.9Hz step), and ”doubled frequency tone range”

(i.e. from 15.6Hz to 3984Hz in 15.6Hz step) ac-

cording to the values described in CONTROL

CONTROL REGISTER CR11

Bit BE(7) permits connection of a f1 squarewave

PWM Ring signal, amplitude modulated or not by

a f2 squarewave signal, to buzzer driver output

BZ. Bits BZ5 to BZ0 define the duty cycle of the

PWM squarewave, according to the following for-

mula:

Duty Cycle = CR11(5

÷ 0) x 0.78125%

where CR11(5

÷ 0) is the decimal equivalent of

the binary value BZ5

÷ BZ0.

When BE = 1, if bits F1 = 1 and F2 = 0 in regis-

ter CR7, a f1 PWM ring signal is present at the

buzzer output, while if bits F1 = 1 and F2 = 1 in

plitude modulated by a f2 squarewave fre-

quen cy. Bit BI (6) allows to chose the logic level

at which the duty cycle is referred: BI = 0 means

that duty cycle is intended as the relative width

of the logic1, while BI = 1 means that duty cycle

is intended as the relative width of the logic 0.

When BE = 0 (or during power down) BZ = 0 if

BI = 0 or BZ = 1 if BI = 1.

ST5090

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