AS2520 austriamicrosystems AG, AS2520 Datasheet
AS2520
Available stocks
Related parts for AS2520
AS2520 Summary of contents
Page 1
... The interface to a dialler/controller is made very simple to allow easy adaptation to a telecom microcontroller. The AS2520 series incorporate volume control for the earpiece and the loudspeaker (AS2520 digital with +/- keys and AS2521 analogue with potentiometer). The volume control circuit automatically compensates the loop gain to ensure acoustic stability ...
Page 2
... Input for enabling loudhearing/handsfree, active high (see table 1). Handset Switch Input This is an input that is pulled high by the hook switch (handset) or µC when off-hook (see table 1). Page 2 AS2520/21/20B/21B -6 dB from mA from mA; gain independent of line current; ( )loudspeaker ...
Page 3
... These are the input pins for the handsfree microphone (electret). Volume Control Input Volume control for the receive signal. AS2520: Digital control with +/– keys or from µC; AS2521: Analogue dc control with potentiometer. Supply Source Control Output This N-channel open drain output controls the external high power source transistor for supplying (V loudhearing/handsfree mode ...
Page 4
... TX-AGC POWER LEVEL DETECTOR V DD VOICE & DC POWER CONTROL PD AS2520/21/20B/21B RX-AGC ST-AMP LOGIC INTERFACE Figure 2: Block Diagramme Page 4 AS2520/21/20B/21B M1 HS MI-AMP M2 M3 MI-AMP M4 RTH LEVEL DETECTOR A A GND RO RO-AMP LSI LO-AMP PDM INPUT ...
Page 5
... Volume Control On the AS2520 the receive gain can be changed by pressing the volume keys. The + key increases the gain steps and the – key decreases the gain steps. The gain is reset by next off-hook ...
Page 6
... The anti-Larsen circuit decreases the gain of the loudspeaker amplifier when a microphone signal is applied signal is applied from the microphone, the loudspeaker amplifier is at its full gain. Anti-Clipping (not AS2520B/21B) The anti-clipping circuit is activated in loudhearing and handsfree mode. The circuit prevents harsh distortion at very high signal levels. ...
Page 7
... The attack time is 4 ms/6 dB and the hold time is 200 ms. A speech compression is activated when a transmit signal with a high amplitude reaches a level corresponding to approximately 460 mV on the line. but provides the Page 7 AS2520/21/20B/21B Z AC PEAK AGC DETECTOR V TH ± ...
Page 8
... TI input (see also application notes for further details). During DTMF dialling the DTMF signal is applied through a capacitor to the TI input and will be fed to the line (pin LI) and to the receive output (RO) as confidence tone. Page 8 AS2520/21/20B/21B 5k6 BC 327 33 n 30V 547 2 ...
Page 9
... Rev. 5.1 Conditions Speech mode Conditions HS = high LE = high HS and LE = high PD = high, CM running PD = high All digital inputs = mA< I < 100 mA LINE 25°C AMB T = 25°C AMB Page 9 AS2520/21/20B/21B +0. 0. Min. Typ.* Max. Units 3.0 4.1 5.5 V 3.0 4.1 5 ...
Page 10
... RMS HS, LH modes mode M1/M2 and M3/M4 Mute activated HS = high 25°C AMB LE = high low 25°C AMB Differential Single ended Test Conditions Z = 1000 ohm 25°C RL AMB Page 10 AS2520/21/20B/21B Min. Typ. Max. Units +/- 0 ...
Page 11
... LPD Rev. 5.1 Condition Volume reset f = 500 Hz to 3.4 kHz Speech mode; LLC = steps, each < 0 RMS Not AS2520B/21B Unloaded Channel control; V > 0 RMS Channel control HS = high 25°C AMB 50 Hz.........20 kHz V < 0 25°C ...
Page 12
... Preliminary Test Circuit Rev. 5.1 AS252x Figure 8: Test Circuit Page 12 AS2520/21/20B/21B May 1999 ...
Page 13
... DD Radio Frequency Interference The RFI sensitivity has been minimised by the consequent use of CMOS technology and one overall ground and by having differential inputs with a relative low input impedance. For further application information see application notes for the AS2520 series. Rev. 5 ...
Page 14
... Austria Mikro Systeme Int. AG reserves the right to change or discontinue this product without notice. Rev. 5.1 Ordering Information Part Package Number Type AS2520 T 28 pin SOP AS2520 P 28 pin DIP AS2520B T 28 pin SOP ...