STLC3075_09 datasheet(10/36 Pages) STMICROELECTRONICS

10 / 36 page

Functional description

STLC3075

10/36

The self generated battery voltage is set to a predefined value in on-hook state.

The typical value of -50 V can be adjusted via one external resistor (RF1). When RING

mode is selected this typical value is increased to -70 V.

Once the line goes in off-hook condition, the DC/DC converter automatically adjusts the

generated battery voltage in order to feed the line with a fixed DC current (programmable via

RLIM) optimizing the power dissipation.

4.2

Operating modes

4.2.1

Power down

When this mode is selected the SLIC is switched off and the TIP and RING pins are in high

impedance. The line detectors are also disabled therefore the off-hook condition cannot be

detected.

The power down mode can be selected in emergency condition when it is necessary to cut

any current delivered to the line.

The power down mode is also forced by STLC3075 in case of thermal overload

(Tj > 140 °C). In this case the device goes back to the previous status as soon as the

junction temperature decrease under the hysteresis threshold.

No AC transmission is possible.

4.2.2

High impedance feeding (HI-Z)

This operating mode is normally selected when the telephone is in on-hook in order to

monitor the line status keeping the power consumption at the minimum.

The output voltage in on-hook condition is equal to the self generated battery voltage (-50 V

typical).

When off-hook occurs the DET becomes active (low logic level).

The off-hook threshold value in HI-Z mode is the same as the programmed value in ACTIVE

mode.

The DC characteristics in HI-Z mode are equal to the self generated battery with

2x(1600

Ω+Rp) in series (see Figure 3), where Rp is the external protection resistance.

No AC transmission is possible.

Figure 3.

DC characteristics in HI-Z mode.

Vbat

Vbat (-50V)

2x(R1+Rp)

Slope: 2x(R1+Rp)

(R1=1600ohm)

STLC3075 датащи(PDF) 10 Page - STMicroelectronics

STLC3075 датащи(HTML) 10 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

датащи скачать

ссылки URL