AS2524BF

austriamicrosystems AG is now ams AG The technical content of this austriamicrosystems datasheet is still valid. Contact information: Headquarters: ams AG Tobelbaderstrasse 30 8141 Unterpremstaetten, Austria Tel: +43 (0) 3136 500 0 e-Mail: ams_sales@ams.com Please visit our website at www.ams.com austriamicrosystems Telephone Line Interface and Speakerphone Circuit AS2523, AS2524, AS2524B - impedance of 1000:) as well as a speech circuit with softclipping, line loss compensation and Rx-volumee control for handset and handsfree operation. It shall act ct ass an a/ba/b line powered device, which is controlled by a CPU U via a serial interface on AS2523 or a standardd dialler er via a parallel interface on AS2524 and AS2524B. 4B. B. Applications App p Enhanced nhance handsfreee feature ature phones with w CallerID and extende displays. Thee AS2524 and extended an AS2524B are devel develo interf nterf com co developed to interface with common Taiwanese dialers. Package ckage age Available lable in 28 28-pin 28-- pin SOIC or die Te Block Diagram AS2523/24 is a CMOS integrated circuit that incorporates DC and AC line adaptation (DC-mask and synthesized ACC- al id - Line/Speakerphone circuit on a 28-pin CMOS-IC, simple inventory: same die for AS2523/24 and AS2523/24B Serial I/F on AS2523, parallel I/F on AS2524 Enhanced voice switching Background noise monitoring Tx- and Rx-gain programmable on AS2523 only Digital volume control of Rx signals on AS2523 only DC characteristic programmable on AS2523 only Dual softclipping in handset mode on AS2523 only Dual softclipping in handsfree mode on AS2523 only Loudspeaker amplifier for loudhearing and handsfree Supply voltage generation for external circuitry Automatic line loss compensation on AS2523 / 24B only Real and complex impedance selectable by external components Side tone adaptation selectable by external components entss Unique EMC performance Operating range from 15mA to 100mA (down too 5mA with reduced performance) Few external components am co s nt AG en ts til - General Description lv Key Features DATA SHEET Revision 1.13 Page 1 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Pin description Pin # Symbol 15 LS Function L ine Current S ense Input Analog input for sensing the line current LI L ine I nput Te ch ni ca a l c ms on A te G nt st ill va lid 12 Analog input used for power extraction and line current sensing 13 RI R eceive I nput Analog input for ac-separated receive signal 9 STB S ide T one B alance Input Analog input for side tone cancellation network 10 CS C urrent S hunt Control Output external high power shunt nt transistor ransistor for fo N-channel open drain output to control thee externa dulation of line lin l synthesizing AC- and DC-impedance, modulation voltagee andd shorting the line during make periods of pulse dialing 16 CI C omplex I mpedance Input cito too program progra prog mplex ex impedance Analog input pin for the capacitor a complex 14 SS S upply S ource Control Output utput N-channel open drain the source transistor for supplying ain output to control c he external high power p peaker amplif amplifi hook ok loudspeaki (Vpp) the loudspeaker amplifier in off-hook loudspeaking/handsfree mode 11 VSS V oltage S ource S ourc ource nalog log Power Po pply Negative Analog Supply 18 VDD V oltage D rain D rain owe Supply pply Positive Analog Power 19 AGND A nalog G round oundd Special ground internal amplifiers und for the in 8 M1 M icrophone crophone Inpu Input 1 Differential ifferential inp input for the handset microphone (electret) 6 M2 M icropho icrophone Input 2 Differential input for the handset microphone (electret) Diffe Differ 7 M3 M icrophone Input 3 Differential input for the handsfree microphone (electret) 5 M4 M icrophone Input 4 Differential input for the handsfree microphone (electret) 17 RO R eceive O utput to H andset Output for driving a dynamic earpiece with an impedance from 150: to 300: Revision 1.13 Page 2 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Pin # Symbol 25 xCS Function C hip S elect on AS2523 Chip select input of the serial interface. Internal pull-up resistor ( 100kOhm ) /xMUTE 26 Mute transmit-, receive- path and activate tone path on AS2524 and AS2524B D ata I nput DI on AS2523 /xPD 27 Power down mode for AS2524 and AS2524B (On-hook) Cl oc k on AS2523 CLK Clock input of the serial interface. Internal pull-up resistor ( 100kOhm ) /HFE Handsfree mode operation on AS2524 and AS2524B L oudspeaker O utput. Output pin is for a 25: LO 2 FT1 3 TXO 4 TXV 1 CBN 20 RECI 21 RECV 24 VSSA 22 VPP 28 TONEIN loudspeaker ic a al m co s nt AG en ts til l 23 va lid Data input of the serial interface. Internal pull-up resistor ( 100kOhm ) Analog input pin for connecting a capacitor for o offset ooff cancellation. Analog output of the transmit signal Analog input for the transmit signal al in the voice switching swi path p Analog input pin for connecting a capacitor apacitor for fo background round noise monitoring. m Analog input for the handsfree free rec receive vee pa ppath. Should ould be connected connect to RO via coupling capacitor. Analog input for receive eceive ceive voice sswitching sw path. th. Power supplyy pin for LO output oou amplifier. mplifier. er. Power supply pply ply pin for LO L output ut amplifier. mplifier. Te ch n Analog input for or DTMF-signals. signals. als. Revision 1.13 Page 3 of 19 Data Sheet AS2523, AS2524, AS2524B austriamicrosystems Te al id Detailed Block Diagram Revision 1.13 Page 4 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Functional Description The gain of the M3/M4 o LS is set to +46dB. This gain can be changed by programming from +39dB to +54dB in 1dB steps on AS2523. The input is differential DC conditions with an impedance of 10k:. The soft clip circuit limits the output voltage at LS to 2V p . There is no LLC for this path. The normal operating mode is from 15mA to 100mA. An operating mode with reduced performance is from 5mA to 15mA. In the line hold range from 0mA to 5mA the device is in a power down mode. Receive path al id The gain of the LS o RO receive path is set to +7.5dB. B to t This gain can be changed by programming from –7.5dB vee input +7.5dB in 1dB steps (Register Rxgain). The receive ft clip circuit is the differential signal of RI and STB. The soft events ts harsh limits the output voltage at RO to 1V p. It prevents distortion and acoustic shock. There is LLC for or this path. The DC characteristic is determined by the voltage at LIpin and a 30: resistor between LI- and LS-pin. It can be calculated by the following equation: V LS = V LI + I Line * 30:. V LI can be programmed to be 3.5V or 4.5V. lv 2/4 wire conversion The gain of the LS o LO receivee path is set +32dB. et to +3 This gain can be changed by programming rogrammin from om +19dB to 34dB in 1dB steps. The user change 34 serr can also chang chan the gain via Register Handsfree receive (See section Regi Regist ceive ve end gain (Se (S "Handsfree"). The receive the differential signal of "Handsfre Handsf ive input is th STB. The soft RI and S oft clip circuit llimits the output voltage at pre ts harsh distortion and acoustic LO to 1.1V p. It prevents for this path. sshock. There here is optional opt option LLC L AC-impedance ic a al m co s nt AG en ts til AS2523/24 has built in two Wheatstone bridges with one common ground. This provides a maximum of independence of AC-impedance and side tone from each other. One can adapt side tone without changing the ACimpedance. The AC-impedance of AS2523/24 is set to t.m. 1000:. :. With the external capacitor at CI-pin it can be programmed ogrammed grammed Line ne Loss oss Compensation Compe Comp (AS2523, AS2524B) complex. With an external resistor of approx. 1.5k 1.5k: : programmable on AS2523 programma not acti activated at AS2524 activ - perm permanently activated at AS2524B per When Wh it is activated, the transmit and receive gains for Whe b both I/O’s are decreased by 6dB at line currents from 20mA to 50mA or from 45mA to 75mA. - connected to the LS-pin it can be programmed mmed med to 600:. 600 600: Side Tone A good side tone cancellation can be achieved achiev by using sing the following equation: Z BAL /Z LINE = 10 Transmit path Handsfree The handsfree function allows voice communication without using the handset (full 2-way speaker phone). Two voice controlled attenuators prevent acoustic coupling between the loudspeaker and the microphone. The voice switching circuit has three states, namely idle, transmit or receive. In receive mode the attenuation of the receive path and the transmit path can be controlled by Register Handsfree receive end gain between 0dB and -20dB. The following table shows how voice switching is controlled The gain of the M1/M2 o LS is set to +37dB. This gain can be changed by programming from +30dB to ming on AS2523 fr fro +45dB in 1dB steps (Register AS2524 / 24B it ster ter Txgain Txgain), on A is set to +37dB per default. fault.. The input is differential with an Te ch n impedance of 10k:. limits the output :. The he soft clip circuit cir ci voltage at LS too 2V p. There is LLC LL for this path. Revision 1.13 voice switching circuit TX_atten RX Voice switching speech Backgnd noise monitor Page 5 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Gmax = +9dB Gmin = -21dB … -40dB (Vol) LINE +23dB +14dB +8dB ~ +17dB TXO speech Peak detector Voice switching TXV RO Compress Compress Offset comp FT1 0mV ~ 100mV Peak detector Peak detector CBN Cmicoffset CBckgnd RECV RECI +9dB ch ni ca a l c ms on A te G nt st i ll Gmax = -4dB … +16dB (Vol) Gmin = -33dB va lid Compress +3dB Speech Mode Rx-gainn Tx-gain Remark Rx > Tx_atten X Receive 0db db to -20dB - 20dB -50dB B to -30dB dB B aadjustable with VOL-setting Tx_atten > Rx NO Idle -25 - 25 -25 25 middle position Tx_atten > Rx YES Transmit -50dB 0d 0d 0dB independent of VOL-setting IDLE-mode DLE-mode RX-mode TX-mode 0dB -10dB TX-gain -20dB Vol max Vol default Vol min -25dB -30dB -40dB RX-gain Te -50dB Revision 1.13 Page 6 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Typical Characteristics of Line Loss Compensation (AS2523, AS2524B only) No LLC (AS2523, AS2524) LLC high (AS2523,AS2524B) LLC low (AS2523) va 35 34 33 32 31 30 29 Tx Gain f = 800 Hz Z LINE = 600: V LS = -10 dBm DC Line Current ic a al m co s nt AG en ts til l (dB) lid The line-loss-compensation is programmable at the AS2523, not activated at the AS2524 and LLC high (45mA-75mA) activated at the AS2524B. 20 30 40 50 60 0 70 80 (mA) Figure 1 Typical Tx Gain Characteristics haracteristics Line Loss Compensation p ation on (dB) +4 +3 +2 +1 0 -1 -2 Rx Gain No L LLC LL (AS2523, AS2524) LLC low (A 3) (AS2523) LLC high (AS2523,AS2524B) f = 800 Hz Z LINE = 600: V LS = -10 dBm VOL = 0 dB (neutral) ral) al) 20 30 DC Line Current 40 50 60 70 80 (mA) Te ch n Figure Rx Gain Characteristics Line Loss Compensation ure 2 Typical T Revision 1.13 Page 7 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Serial Interface on AS2523 Registers The settings of the AS2523 are stored in 16 registers. Each register has 4 bit data width. va lid Timing The data format for writing to a register has the following form: xCS Te ch ni ca a l c ms on A te G nt st ill CLK A3 DI Note: A0 A1 A2 D3 D2 D1 D0 D The pins xCS,CLK,DI have internal pull-up resistors. s. Parameter Symbol MIN CLK Pulse width HIGH T6 100ns 00ns ns CLK Pulse width LOW T5 100ns xCS to first falling CLKedge setup time T1 50n 50ns DIN to CLK setup time T33 50ns ns DIN to CLK hold time T4 50ns 0nss t3 MAX t6 t5 t1 TYP YP t4 xCS CLK DIN Revision 1.13 Page 8 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Serial interface Registers The following table shows the content of the 16 control registers. Data A A A A 3 2 1 0 D D D D 3 2 1 0 0 0 0 0 0 Nop x x Conf-Tone: 0... No Conf Tone 1... Conf Tone for AS2523, AS2524HF for AS2524 LH bond option na na na na 0111 na na na na 0111 lid x Llc0 x Llc1 0 1 0 1 0 Liv 0 0 1 1 0 Conf 0 0 0 0 1 Default value after reset Control registers AS2523 LIV: Voltage at pin LI 0...3.5V, 1...4.5V LLC1 LLC0: Line loss compensation setting 0 0 20mA-50mA 0 1 NO Line loss compensation 1 0 45-75mA 1 1 NO Line loss compensation 0 1 0 1 0001 0001 Burl CT1 CT0 x x x x 1100 1111 1011 0000 1100 16 gains Hfs1 HFs0: s0: Speed of voice switching 0 0 max speed 0 1 1 0 1 1 min sp spe speed Transmit gain [16], 16 steps, 1dB stepsize 0111 0111 16 gains Data HS-mo Da HSHS-mode HF-mode 0x0 3 30dB 39dB : : : 0xF 45dB 54dB Rec Re Receive gain [16], 16 steps, 1dB stepsize 1111 1111 0100 1000 0100 0101 0000 0001 na na Softclip-settings, Tx_comp_gain settings Soft-TX 0 0101 Soft-RX 1000 tx_comp_gain Bit0 00 1000 tx_comp_gain Bit 1 0 1 1 0 Burs Te ch ni ca a l c ms on A te G nt st ill BURS: Analog tone at RO 0...OFF, 1...ON BURL: Analog tone at LS 0...OFF, 1...ON CT1 CT0: @RO @LS 0 0 -36dB -15dB TONE-confidence level 0 1 -30dB -9dB rel. to pin LS 1 0 -24dB -3dB 1 1 -18dB +3dB va Address Bit1 Bit0 :Tx_comp_gain 0 0 +8dB 0 1 +11dB 1 0 +14dB 1 1 +17dB SOFTRX: Softclip RX 0...OFF, FF, SOFTTX: Softclip TX 0...OFF, F, 1 0 0 0 Bnon Delay_10ms Rxoffset Bit0 Rxoffset Bit1 0 1 1 1 16 gains Bit1 Bit0: Rx-offset setting 0 0 0mV 0 1 12mV 1 0 40mV 1 1 100mV Delay_10ms 0... no delay B Bnon 0... BGN off ndgain Handsfree receive endgain Data 0x0 : 0xF 1 0 0 1 x x x 1...ON 1...ON ain RXgain 0dB -20dB : +0dB TXgain -30dB .. . 10ms delay 1... . BGN on 1... eive volume Min. receive -50 -50dB eive volume Max. receive x 1 0 1 0 1 0 1 1 Hfs0 Hfs1 off0 off1 off1 off0: BGN-offset 0 0 120mV 0m 0 1 180mV 40mV 1 0 240mV 0mV 1 1 300mV Data 0x0 : 0xF Tone x x x x His 0 1 1 1 1 HF x 0 0 1 1 LH: x 0 1 0 1 1... 1... 1... 1... fg=2000Hz Rxcomp=RECV Tx-path muted Ton in signal path No mask 1... Mask acitivated Hook functions Power down Handset not allowed Handsfree Loudhearing slow_rec LH Mute Hf Rec_on His x Mask x fg=200Hz Rxcomp=AGND No mute Tx-signal path Test2 1 1 1 1 x HP_on : 0... rec_on : 0... Mute : 0... Tone : 0... Mask, Lh, Hf, Hook Switch Mask: 0... Test3 1 1 1 0 x HF-mode 19dB : 34dB Krat5 1 1 0 1 HP_on 1 1 0 0 HS-mode -6dB : +9dB slow_rec: fast change to TX, slow change to RX, no IDLE Krat5,Test3,Test2: For factory test only ! x x x x Reset to defaults For a detailed description of the commands see Application note AN523/24. Revision 1.13 Page 9 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Programming Guidelines for the AS2523 Additional settings in Handsfree mode The AS2523 is programmed by means of a serial 8-bit shift register. MSB is clocked in first, LSB last. The first four bits (7,6,5,4) are the addresses of the registers, the last four bits (3,2,1,0) are the data bits. Note: change the default settings only if necessary: Each register has a default setting (see data sheet), which is set after power-up of the chip. b) Change the Tx comparator preamplifier gain in register 6 Default = 14dB The internal registers are RAM-cells. When the AS2523 loses VDD (as in on-hook state) it also loses the register contents. c) Change the Receive DC offset and Background noise oise monitoring in Register 7 default = 0mV offset (higher val. puts moree weight eight on Rx) switching delay default = on Background Noise Monitoring = on It is therefore necessary to re-write the affected registers after each hook event. The register contents cannot be read, they can only be written. me in register egister 8 d) Set the speaker amplifier volume Default = 0B lv al id a) A click-free startup can be achieved by starting up in handset mode (=default) and then switching to handsfree, once the chip has stabilized. e) Set the handsfree voice ce switching speed spee and Ba onitoring offset in register 9: Background Noise monitoring defa defau witching hing speed = 1ms/6dB (fastest) default voice switching def defa onitoring toring of offse default BGN monitoring offset = 240mV (determines the T requir equir too switch switc from idle to Transmit) Tx level required ic a al m co s nt AG en ts til Registers need to be re-written after each power-up and after each hook event (handset / handsfree / on-hook). eset et It is recommended to always initialize the chip with a “reset to defaults command” (Fx) first and then write the he appropriate registers that need to be changed from the default setting. re- written in a Alternatively, all registers (4 to 16) may be re re-written handset / bulk at each power-up and hook event (handset handsfree / on-hook). ase se of unexpected u cted loss ss This guarantees safe operation in case gisters of power during normal operation. Re-writing alll registers terr also eases later software updates, as only register ditional tiona command mand contents need to be changed, but no additional lines need to be inserted. Example of a typical power-up er-up up sequence sequenc ch n A typical power-up sequence ence ce will require the th following programming. a) determine the cause of powe power-up (handset / handsfree mode) and set register D accordingly. ault = handset mo m Default mode Te b) Set et the LI voltage volta to 3.5V or 4.5V (default = 4.5V) and Line Compensation (default = off) in register 4 ne Loss C c) Set the t Confidence Tone level (e.g. the DTMF level w which is audible in the handset) and path in register 5 Default = off d) Set the required Tx and Rx gains in Registers A and B Default = 37dB Tx gain, 1dB Rx gain Revision 1.13 Additional itional nal settings during Flash During ng a Flash, th the AS2523 should be powered down to avoid oid dis discharg charg of VDD: discharge Set the MA MASK bit (bit3 in register D) to 1 After th the line current is restored, the MASK bit must be cle clea cleared again. Other settings do not need to be re-written, as VDD has not discharged. As a safety margin however, it is recommended to re-write all registers after a flash Additional settings during line breaks If a line-break-detection (brief interruption of the line while in off-hook state) is implemented, the same rules apply as for a Flash: set the MASK bit to 1 to avoid discharge of VDD. It is recommended to re-write all registers after a line-break, as a line break may take long enough to discharge VDD, even when the MASK bit was set. General Rules The serial interface may be programmed at any time, it does not affect the speech quality, e.g. if a register is overwritten with the same value. It is also possible to re-write all registers periodically. The register is static, therefore it can be clocked at any speed up to 5MHz. However, electromagnetic pulses on the clock and data lines may cause unwanted programming of the chip. It is therefore recommended to keep these lines short, filter them by a discrete lowpass filter and reduce the clock speed accordingly. Page 10 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Parallel Interface on AS2524 and AS2524B Input Signal on Pin xMute HF 0 0 0 Power down Mode 0 0 1 Power down 0 1 0 Power down 0 1 1 Power down 1 0 0 Tone mode 1 0 1 Tone mode 1 1 0 Handset mode 1 1 1 Handsfree mode al id XPD lv Power down mode Te ch ni ca a l c ms on A te G nt st il For low power consumption the analog part is turned off during activated power down mode. The Power ower down mode m e is used during Flash and Pulse dialing and for On-hook operation. Handset mode Speech mode is Handset mode (M1-M2, RO active; LO deactivated) activated) ctivated) Parameter AS2524 AS2524B AS25 4.5V 4.5V 4 LLC No LLC LL LLC high i g (45mA A to 75mA) 5mA) TX-Gain +37dB +43dB 4 43dB RX-Gain +7.5dB +7.5dB 7.5dB Rx-Softclip Off ff Off Tx-Softclip Off Off O Tone Offf Off LI Voltage Handsfree mode Speech mode is Handsfree mode (M3-M4, -M4,, RO ac active; acti LO active) Parameter AS2524 24 AS2524B 4.5V 4.5V LLC No LLC LLC high (45mA to 75mA) HF TX-Gain +4 +46 +46dB +52dB HF RX-Gain +34dB +34dB Rx-Softclip lip Off Off Tx-Softclip Softclipp Off Off Tonee Off Off BNM On On LI Voltage Revision 1.13 Page 11 of 19 austriamicrosystems Data Sheet AS2523, AS2524, AS2524B Tone mode This mode is used to send DTMF and FSK data to the line. Speech mode is Tone mode (M1-M2;M3-M4 muted, Rx path muted, RO and LO active) LI Voltage AS2524B 4.5V 4.5V LLC No LLC LLC high (45mA to 75mA) Tone TX-Gain +14dB +14dB -36dB@Ro –15dB@Lo relative to Pin LS -36dB@Ro –15dB@Lo relative to Pin LS Confidence tone level lid AS2524 va Parameter Loudhearing AS2524 and AS2524B (feature only available as DIE) Speech mode is Loudhearing (M3-M4, RO active; LO activated). Loudhearing can be activated via a bond-option (see document “AS2523/24 Delivery as Dice”). AS2524 AS2524B 24B 4.5V 4.5V .5V LLC No LLC LLC highh (45mA to 775 75mA) TX-Gain +37dB B +43dB RX-Gain +7.5dB .5dB +7.5dB 7 Tone O Off Off Slow_rec On On RECV pin Deactiv Deactivated Deactivated Highpass 2000kHz (10 (10n (10nF from TXO TXO->TXV) O - >TXV) 2000kHz (10nF from TXO->TXV) 120ms/6dB s/6dB 120ms/6dB 300mV mV 300mV Te ch ni ca a l c ms on A te G nt st ill Parameter LI Voltage Voice switching speed RX-Offset Electrical characteristics Electrical characteristics are measuredd withh the Test T Circuit Ci application. Typical mean values will not ot be tested. tested Absolute maximum ratings ng ngs Positive Supply Voltage age Input Current Input Voltagee (LS) Input Voltage oltage ge (LI, CS) CS Input ut Voltage age (STB, (STB RI) Digital Input Vol Voltage Electrostati Discharge (HBM 1.5k:-100pF) Electrostatic Storage torag Temperature -0.3V