Am79R70 Ringing Subscriber Line Interface Circuit DISTINCTIVE CHARACTERISTICS Ideal for ISDN-TA and set top applications On-chip ringing with on-chip ring-trip detector Low standby state power Battery operation: — VBAT1: –40 V to –67 V — VBAT2: –19 V to VBAT1 On-chip battery switching and feed selection On-hook transmission Polarity reversal option Programmable constant-current feed Programmable Open Circuit voltage Programmable loop-detect threshold Current gain = 1000 Two-wire impedance set by single component Ground-key detector Tip Open state for ground-start lines Internal VEE regulator (no external –5 V power supply required) Two on-chip relay drivers and snubber circuits BLOCK DIAGRAM Relay Driver RTRIP1 RTRIP2 RYOUT2 RYE Relay Driver A(TIP) Ring-Trip Detector Input Decoder and Control Ground-Key Detector HPA Two-Wire Interface D1 D2 C1 C2 C3 Off-Hook Detector E1 DET Signal Transmission RD VTX RSN HPB B(RING) RYOUT1 Power-Feed Controller RINGIN RDC RDCR VBAT2 VBAT1 RSGL RSGH B2EN Switch Driver VCC VNEG BGND AGND/DGND Publication# 080211 Rev: D Amendment: /0 Issue Date: October 1999 GENERAL DESCRIPTION The Legerity family of subscriber line interface circuit (SLIC) products provide the telephone interface functions required throughout the worldwide market. Legerity SLIC devices address all major telephony markets including central office (CO), private branch exchange (PBX), digital loop carrier (DLC), fiber-in-the-loop (FITL), radio-in-the-loop (RITL), hybrid fiber coax (HFC), and video telephony applications. The Legerity SLIC devices offer support of BORSHT (battery feed, overvoltage protection, ringing, supervision, hybrid, and test) functions with features including current limiting, on-hook transmission, polarity reversal, tip-open, and loop-current detection. These features allow reduction of linecard cost by minimizing component count, conserving board space, and supporting automated manufacturing. The Legerity SLIC devices provide the two- to four-wire hybrid function, DC loop feed, and two-wire supervision. Two-wire termination is programmed by a scaled impedance network. Transhybrid balance can be achieved with an external balance circuit or simply programmed using a companion Legerity codec device, the Am79C02/03/ 031 DSLAC™ device, the Am79Q02/021/031 Programmable Quad SLAC (QSLAC™) device, or the Am79Q5457/4457 Nonprogrammable QSLAC device. 2 The Am79R70 Ringing SLIC device is a bipolar monolithic SLIC that offers on-chip ringing. Now designers can achieve significant cost reductions at the system level for short-loop applications by integrating the ringing function on chip. Examples of such applications would be ISDN Terminal Adaptors and set top boxes. Using a CMOS-compatible input waveform and wave shaping R-C network, the Am79R70 Ringing SLIC can provide trapezoidal wave ringing to meet various design requirements. In order to further enhance the suitability of this device in short-loop, distributed switching applications, Legerity has maximized power savings by incorporating battery switching on chip. The Am79R70 Ringing SLIC device switches between two battery supplies such that in the Off-hook (active) state, a low battery is used to save power. In order to meet the Open Circuit voltage requirements of fax machines and maintenance termination units (MTU), the SLIC automatically switches to a higher voltage in the On-hook (standby) state. Like all of the Legerity SLIC devices, the Am79R70 Ringing SLIC device supports on-hook transmission, ring-trip detection and programmable loop-detect threshold. The Am79R70 Ringing SLIC device is a programmable constant-current feed device with two onchip relay drivers to operate external relays. This unique device is available in the proven Legerity 75 V bipolar process in 32-pin PLCC packages. Am79R70 Data Sheet ORDERING INFORMATION Standard Products Legerity standard products are available in several packages and operating ranges. The order number (Valid Combination) is formed by a combination of the elements below. Am79R70 J C TEMPERATURE RANGE C = Commercial (0°C to 70°C)* PACKAGE TYPE J = 32-pin Plastic Leaded Chip Carrier (PL 032) S = 28-pin Small Outline Integrated Circuit (SOW 028) POLARITY REVERSAL OPTION Blank = No Polarity Reversal –1 = Polarity Reversal DEVICE NUMBER/DESCRIPTION Am79R70 Subscriber Line Interface Circuit Valid Combinations Valid Combinations Am79R70 –1 JC SC Valid Combinations list configurations planned to be supported in volume for this device. Consult the local Legerity sales office to confirm availability of specific valid combinations, to check on newly released combinations, and to obtain additional data on Legerity’s standard military–grade products. Note: * Functionality of the device from 0°C to +70°C is guaranteed by production testing. Am79R70 Data Sheet 3 CONNECTION DIAGRAMS Top View VCC VBAT2 BGND B(RING) A(TIP) 4 3 2 1 32 31 30 RD RYOUT2 32-Pin PLCC RYOUT1 6 28 RTRIP2 B2EN 7 27 HPB VBAT1 8 26 HPA D1 9 25 RINGIN E1 10 24 RDCR C3 11 23 VTX C2 12 22 VNEG DET 13 21 RSN 18 19 20 AGND/DGND 16 17 RDC 15 NC 14 RSGL RTRIP1 RSGH 29 D2 5 C1 RYE 28-Pin SOIC Notes: 1. Pin 1 is marked for orientation. RSVD 1 28 VBAT1 E1 2 27 B2EN C3 3 26 RSVD C2 4 25 VBAT2 DET 5 24 VCC C1 6 23 BGND RSGH 7 22 B(RING) RSGL 8 21 A(TIP) RDC 9 20 RD AGND 10 19 RTRIP1 RSN 11 18 RTRIP2 VNEG 12 17 HPB VTX 13 16 HPA RDCR 14 15 RINGIN 2. NC = No connect 3. RSVD = Reserved. Do not connect to this pin. 4 Am79R70 Data Sheet PIN DESCRIPTIONS Pin Names Type Description AGND/DGND Gnd Analog and digital ground are connected internally to a single pin. A(TIP) Output Output of A(TIP) power amplifier. B2EN Input VBAT2 enable. Logic Low enables operation from VBAT2. Logic High enables operation from VBAT1. TTL compatible. BGND Gnd Battery (power) ground B(RING) Output Output of B(RING) power amplifier. C3–C1 Input Decoder. TTL compatible. C3 is MSB and C1 is LSB. D1 Input Relay1 control. TTL compatible. Logic Low activates the Relay1 relay driver. D2 Input (Option) Relay2 control. TTL compatible. Logic Low activates the Relay2 relay driver. DET Output Detector. Logic Low indicates that the selected detector is tripped. Logic inputs C3–C1 and E1 select the detector. Open-collector with a built-in 15 kΩ pull-up resistor. E1 Input (Option) A logic High selects the off-hook detector. A logic Low selects the ground-key detector. TTL compatible. HPA Capacitor High-pass filter capacitor. A(TIP) side of high-pass filter capacitor. HPB Capacitor High-pass filter capacitor. B(RING) side of high-pass filter capacitor. RD Resistor Detect resistor. Threshold modification and filter point for the off-hook detector. RDC Resistor DC feed resistor. Connection point for the DC-feed current programming network, which also connects to the receiver summing node (RSN). VRDC is negative for normal polarity and positive for reverse polarity. RDCR — Connection point for feedback during ringing. RINGIN Input Ring Signal Input. Pin for ring signal input. Square-wave shaped by external RC filter. Requires 50% duty cycle. CMOS-compatible input. RSGH Input Saturation Guard High. Pin for resistor to adjust Open Circuit voltage when operating from VBAT1. RSGL Input Saturation Guard Low. Pin for resistor to adjust the anti-saturation cut-in voltage when operating from both VBAT1 and VBAT2. RSN Input The metallic current (AC and DC) between A(TIP) and B(RING) is equal to 1000 x the current into this pin. The networks that program receive gain, two-wire impedance, and feed resistance all connect to this node. RTRIP1 Input Ring-trip detector. Ring-trip detector threshold set and filter pin. RTRIP2 Input Ring-trip detector threshold offset (switch to VBAT1). For power conservation in any nonringing state, this switch is open. RYE Output Common Emitter of RYOUT1/RYOUT2. Emitter output of RYOUT1 and RYOUT2. Normally connected to relay ground. RYOUT1 Output Relay/switch driver. Open-collector driver with emitter internally connected to RYE. RYOUT2 Output (Option) Relay/switch driver. Open-collector driver with emitter internally connected to RYE. VBAT1 Battery Battery supply and connection to substrate. VBAT2 Battery Power supply to output amplifiers. Connect to off-hook battery through a diode. VCC Power Positive analog power supply. VNEG Power Negative analog power supply. This pin is the return for the internal VEE regulator. VTX Output Transmit Audio. This output is a 0.5066 gain version of the A(TIP) and B(RING) metallic AC voltage. VTX also sources the two-wire input impedance programming network. Am79r70 Data Sheet 5 ABSOLUTE MAXIMUM RATINGS OPERATING RANGES Storage temperature ......................... –55°C to +150°C Commercial (C) Devices VCC with respect to AGND/DGND .......... 0.4 V to +7 V Ambient temperature ............................. 0°C to +70°C* VNEG with respect to AGND/DGND ...... 0.4 V to VBAT2 VCC ..................................................... 4.75 V to 5.25 V VBAT2 ....................................................VBAT1 to GND VNEG ..................................................–4.75 V to VBAT2 VBAT1 with respect to AGND/DGND: Continuous..................................... +0.4 V to –80 V 10 ms ............................................. +0.4 V to –85 V VBAT1 .................................................... –40 V to –67 V BGND with respect to AGND/DGND........ +3 V to –3 V A(TIP) or B(RING) to BGND: Continuous ...............................VBAT1 –5 V to +1 V 10 ms (f = 0.1 Hz) ..................VBAT1 –10 V to +5 V 1 µs (f = 0.1 Hz) .....................VBAT1 –15 V to +8 V 250 ns (f = 0.1 Hz) ...............VBAT1 –20 V to +12 V Current from A(TIP) or B(RING).....................±150 mA VBAT2 ....................................................–19 V to VBAT1 AGND/DGND.......................................................... 0 V BGND with respect to AGND/DGND ........................ –100 mV to +100 mV Load resistance on VTX to ground .............. 20 kΩ min The Operating Ranges define those limits between which the functionality of the device is guaranteed. * Functionality of the device from 0°C to +70°C is guaranteed by production testing. RYOUT1, RYOUT2 current................................75 mA RYOUT1, RYOUT2 voltage ..................... RYE to +7 V RYOUT1, RYOUT2 transient ................. RYE to +10 V RYE voltage ........................................ BGND to VBAT1 C3–C1, D2–D1, E1, B2EN, and RINGIN Input voltage .........................–0.4 V to VCC + 0.4 V Maximum power dissipation, continuous, TA = 70°C, No heat sink (See note): In 32-pin PLCC package..............................1.67 W In 28-pin SOIC package ..............................1.25 W Thermal Data:................................................................ θJA In 32-pin PLCC package....................... 45°C/W typ In 28-pin SOIC package ........................ 60°C/W typ Note: Thermal limiting circuitry on chip will shut down the circuit at a junction temperature of about 165°C. The device should never see this temperature and operation above 145°C junction temperature may degrade device reliability. See the SLIC Packaging Considerations for more information. Stresses above those listed under Absolute Maximum Ratings may cause permanent device failure. Functionality at or above these limits is not implied. Exposure to Absolute Maximum Ratings for extended periods may affect device reliability. 6 Am79R70 Data Sheet ELECTRICAL CHARACTERISTICS Description Test Conditions (See Note 1) Min Typ Max 200 Hz to 3.4 kHz (Test Circuit D) 26 Unit Note dB 1, 4, 6 3 20 Ω 4 +50 mV 20 Ω 4 2.5 Vpk 2a 0.88 Vrms 2b dB 5 Transmission Performance 2-wire return loss ZVTX, analog output impedance VVTX, analog output offset voltage –50 ZRSN, analog input impedance 1 Overload level, 2-wire and 4-wire, off hook Active state Overload level, 2-wire On hook, RLAC = 600 Ω THD (Total Harmonic Distortion) +3 dBm, BAT2 = –24 V THD, on hook, OHT state 0 dBm, RLAC = 600 Ω, BAT1 = –67 V –64 –50 –40 Longitudinal Performance (See Test Circuit C) Longitudinal to metallic L-T, L-4 balance 200 Hz to 3.4 kHz 40 Longitudinal signal generation 4-L 200 Hz to 800 Hz, Normal polarity 40 Longitudinal current per pin (A or B) Active or OHT state 12 Longitudinal impedance at A or B 0 to 100 Hz, TA = +25°C dB 28 mArms 25 Ω/pin 4 Idle Channel Noise C-message weighted noise +7 +14 dBrnC Psophometric weighted noise –83 –76 dBmp 4 Insertion Loss and Four- to Four-Wire Balance Return Signal (See Test Circuits A and B) Gain accuracy 4- to 2-wire 0 dBm, 1 kHz –0.20 0 +0.20 Gain accuracy 2- to 4-wire and 4- to 4-wire 0 dBm, 1 kHz –6.22 –6.02 –5.82 Gain accuracy 4- to 2-wire OHT state, on hook –0.35 0 +0.35 Gain accuracy 2- to 4-wire and 4- to 4-wire OHT state, on hook –6.37 –6.02 –5.77 Gain accuracy over frequency 300 to 3400 Hz relative to 1 kHz –0.10 +0.10 Gain tracking +3 dBm to –55 dBm relative to 0 dBm –0.10 +0.10 3, 4 Gain tracking OHT state, on hook 0 dBm to –37 dBm +3 dBm to 0 dBm –0.10 –0.35 +0.10 +0.35 3, 4 3 Group delay 0 dBm, 1 kHz 3 dB Am79r70 Data Sheet 3 µs 1, 4, 6 7 ELECTRICAL CHARACTERISTICS (CONTINUED) Description Test Conditions (See Note 1) Min Typ Max 1.1IL Unit Note Line Characteristics IL, Loop-current accuracy IL in constant-current region, B2EN = 0 0.9IL IL IL, Long loops, Active state RLDC = 600 Ω, RSGL = open RLDC = 750 Ω, RSGL = short 20 20 21.7 0.8IL IL IL, Accuracy, Standby state V BAT1 – 10 V I L = -------------------------------------R L + 400 mA IL = constant-current region TA = 25°C ILLIM 1.2IL 18 Active, A and B to ground OHT, A and B to ground 27 39 55 55 110 4 IL, Loop current, Open Circuit state RL = 0 100 IA, Pin A leakage, Tip Open state RL = 0 100 IB, Pin B current, Tip Open state B to ground VA, Standby, ground-start signaling A to –48 V = 7 kΩ, B to ground = 100 Ω 34 –7.5 µA mA –5 4 V VAB, Open Circuit voltage 42 7 Power Supply Rejection Ratio (VRIPPLE = 100 mVrms), Active Normal State VCC 50 Hz to 3400 Hz 33 50 VNEG 50 Hz to 3400 Hz 30 40 VBAT1 50 Hz to 3400 Hz 30 50 VBAT2 50 Hz to 3400 Hz 30 50 dB 5 Power Dissipation On hook, Open Circuit state VBAT1 48 100 On hook, Standby state VBAT2 55 80 On hook, OHT state VBAT1 200 300 On hook, Active state VBAT1 220 350 Off hook, Standby state VBAT1 or VBAT2 RL = 300 Ω 2000 2800 Off hook, OHT state VBAT1 RL = 300 Ω 2000 2200 Off hook, Active state VBAT2 RL = 300 Ω 550 750 9 mW 9 Supply Currents ICC, On-hook VCC supply current Open Circuit state Standby state OHT state Active state–normal 3.0 3.2 6.2 6.5 4.5 5.5 8.0 9.0 INEG, On-hook VNEG supply current Open Circuit state Standby state OHT state Active state–normal 0.1 0.1 0.7 0.7 0.2 0.2 1.1 1.1 Open Circuit state Standby state OHT state Active state–normal 0.45 0.6 2.0 2.7 1.0 1.5 4.0 5.0 IBAT, On-hook VBAT supply current 8 Am79R70 Data Sheet mA ELECTRICAL CHARACTERISTICS (continued) Description Test Conditions (See Note 1) Min Typ Max Unit Note Logic Inputs (C3–C1, D2–D1, E1, and B2EN) VIH, Input High voltage 2.0 VIL, Input Low voltage 0.8 IIH, Input High current –75 40 IIL, Input Low current –400 V µA Logic Output DET VOL, Output Low voltage IOUT = 0.8 mA, 15 kΩ to VCC 0.40 VOH, Output High voltage IOUT = –0.1 mA, 15 kΩ to VCC 2.4 BAT1 – 1 IRTD = æè ---------------------------- + 24 µAöø • 335 RRT1 –10 VAB, Ringing Bat1 = –67 V, ringload = 1570 Ω 57 VAB Ringing offset VRINGIN = 2.5 V V Ring-Trip Detector Input Ring detect accuracy +10 % Ring Signal ∆VAB/∆VRINGIN (RINGIN gain) 61 Vpk 0 V 180 — Ground-Key Detector Thresholds Ground-key resistive threshold B to ground Ground-key current threshold B to ground 2 5 10 11 kΩ mA Loop Detector RLTH, Loop-resistance detect threshold Active, VBAT1 Active, VBAT2 Standby –20 –20 –12 20 20 12 % 8 Relay Driver Output (RELAY1 and 2) VOL, On voltage (each output) IOL = 30 mA +0.25 +0.4 VOL, On voltage (each output) IOL = 40 mA +0.30 +0.8 IOH, Off leakage (each output) VOH = +5 V Zener breakover (each output) IZ = 100 µA Zener on voltage (each output) IZ = 30 mA 100 6.6 7.9 11 V 4 µA V RELAY DRIVER SCHEMATIC RYOUT2 RYOUT1 RYE BGND BGND Am79R70 Data Sheet 9 Notes: 1. Unless otherwise noted, test conditions are BAT1 = –67 V, BAT2 = –24 V, VCC = +5 V, VNEG = –5 V, RL = 600 Ω, RDC1 = 80 kΩ, RDC2 = 20 kΩ, RD = 75 kΩ, no fuse resistors, CHP = 0.018 µF, CDC = 1.2 µF, D1 = D2 = 1N400x, two-wire AC input impedance (ZSL) is a 600 Ω resistance synthesized by the programming network shown below. RSGL = open, RSGH = open, RDCR = 2 kΩ, RRT1 = 430 kΩ, RRT2 = 12 kΩ, CRT = 1.5 µF, RSLEW = 150 kΩ, CSLEW = 0.33 µF. VTX RT1 = 150 kΩ RT2 = 150 kΩ CT1 = 60 pF RSN RRX = 300 kΩ ~ VRX 2. a. Overload level is defined when THD = 1%. b. Overload level is defined when THD = 1.5%. 3. Balance return signal is the signal generated at VTX by VRX. This specification assumes that the two-wire AC load impedance matches the programmed impedance. 4. Not tested in production. This parameter is guaranteed by characterization or correlation to other tests. 5. This parameter is tested at 1 kHz in production. Performance at other frequencies is guaranteed by characterization. 6. Group delay can be greatly reduced by using a ZT network such as that shown in Note 1 above. The network reduces the group delay to less than 2 µs and increases 2WRL. The effect of group delay on linecard performance may also be compensated for by synthesizing complex impedance with the QSLAC or DSLAC device. 7. Open Circuit VAB can be modified using RSGH. 8. RD must be greater than 56 kΩ. Refer to Table 2 for typical value of RLTH. 9. Lower power is achieved by switching into low-battery state in standby. Standby loop current is returned to VBAT1 regardless of the battery selected. Table 1. SLIC Decoding (DET) Output State C3 C2 C1 2-Wire Status E1 = 1 E1 = 0 0 0 0 0 Open Circuit Ring trip Ring trip 1 0 0 1 Ringing Ring trip Ring trip 2 0 1 0 Active Loop detector Ground key 3 0 1 1 On-hook TX (OHT) Loop detector Ground key 4 1 0 0 Tip Open Loop detector Ground key B2EN = 1** 5 1 0 1 Standby Loop detector Ground key VBAT1 6* 1 1 0 Active Polarity Reversal Loop detector Ground key 7* 1 1 1 OHT Polarity Reversal Loop detector Ground key Notes: * Only –1 performance grade devices support polarity reversal. ** For correct ground-start operation using Tip Open, VBAT1 on-hook battery must be used. 10 Battery Selection Am79R70 Data Sheet B2EN B2EN Table 2. User-Programmable Components Z T = 500 ( Z 2WIN – 2RF ) ZT is connected between the VTX and RSN pins. The fuse resistors are RF, and Z2WIN is the desired 2-wire AC input impedance. When computing ZT, the internal current amplifier pole and any external stray capacitance between VTX and RSN must be taken into account. ZL 1000 • ZT Z RX = ------------ • -------------------------------------------------G42L ZT + 500 ( ZL + 2R F ) ZRX is connected from VRX to RSN. ZT is defined above, and G42L is the desired receive gain. 2500 R DC1 + R DC2 = --------------I LOOP RDC1, RDC2, and CDC form the network connected to the RDC pin. ILOOP is the desired loop current in the constant-current region. 3000 R DCR1 + RDCR2 = ---------------------Iringlim RDCR1, RDCR2, and CDCR form the network connected to the RDCR pin. See Applications Circuit for these components. R DC1 + R DC2 C DC = 19 ms • --------------------------------RDC1 R DC2 C DCR R DCR1 + R DCR2 = ---------------------------------------- • 150 µs R DCR1 R DCR2 R D = R LTH • 12.67 for high battery state CDCR sets the ringing time constant, which can be between 15 µs and 150 µs. RD is the resistor connected from the RD pin to GND and RLTH is the loop-resistance threshold between on-hook and off-hook detection. RD should be greater than 56 kΩ to guarantee detection will occur in the Standby state. Choose the value of RD for high battery state; then use the equation for RLTH to find where the threshold is for low battery. Loop-Threshold Detect Equations RD R LTH = ------------ for high battery 12.67 This is the same equation as for RD in the preceding equation, except solved for RLTH. RD R LTH = ------------ for low battery 11.37 For low battery, the detect threshold is slightly higher, which will avoid oscillating between states. V BAT1 – 10 R LTH = ----------------------------- • R D – 400 – 2R F 915 RLTH standby < RLTH active VBAT1 < RLTH active VBAT2, which will guarantee no unstable states under all operating conditions. This equation will show at what resistance the standby threshold will be; it is actually a current threshold rather than a resistance threshold, which is shown by the Vbat dependency. Am79R70 Data Sheet 11 DC FEED CHARACTERISTICS 50 5) VAPPH High Battery Anti-Sat 4) VASH 40 VAB (Volts) 30 1) Constant-Current Region 20 3) VAPPL Low Battery Anti-Sat 2) VASL 10 0 30 IL (mA) Figure 1. Typical VAB vs. IL DC Feed Characteristics R DC = R DC1 + R DC2 = 20 kΩ + 80 kΩ = 100 kΩ ( V BAT1 = – 67 V , V BAT2 = – 24 V ) Notes: 1. Constant-current region: 2500 V AB = IL R L = ------------- R L ; where R L = R L + 2RF RDC 2. Low battery 1000 • ( 104 • 10 + R SGL ) V ASL = ------------------------------------------------------------------- ; where RSGL = resistor to GND, B2EN = logic Low. 3 6720 • 10 + ( 80 • R SGL ) 3 3 Anti-sat region: 1000 • ( R SGL – 56 • 10 ) V ASL = --------------------------------------------------------------- ; where RSGL = resistor to VCC, B2EN = logic Low. 3 6720 • 10 + ( 80 • R SGL ) RSGL to VCC must be greater than 100 kΩ. 3. V APPL = 4.17 + V ASL V APPL I LOOPL = -----------------------------------------------------------------------------( RDC1 + R DC2 ) -------------------------------------- + 2R F + R LOOP 600 4. High battery V ASH = V ASHH + V ASL 3 Anti-sat region: 1000 • ( 70 • 10 + R SGH ) V ASHH = ----------------------------------------------------------------------- ; where RSGH = resistor to GND, B2EN = logic High. 3 1934 • 10 + ( 31.75 • RSGH ) 3 1000 • ( R SGH + 2.75 • 10 ) V ASHH = ----------------------------------------------------------------------- ; where RSGH = resistor to VCC, B2EN = logic High. 3 1934 • 10 + ( 31.75 • RSGH ) RSGH to VCC must be greater than 100 kΩ. 5. V APPH = 4.17 + VASH V APPH I LOOPH = -----------------------------------------------------------------------------( R DC1 + R DC2 ) -------------------------------------- + 2RF + R LOOP 600 12 Am79R70 Data Sheet RING-TRIP COMPONENTS R RT2 = 12 kΩ C RT = 1.5 µF V BAT1 R RT1 = 320 • CF • ------------------------------------------------------------------------------------------------------------------------------------------ • ( R LRT + 150 + 2RF ) VBAT1 – 5 – ( 24 µA • 320 • CF • ( R LRT + 150 + 2R F ) ) where RLRT = Loop-detection threshold resistance for ring trip and CF = Crest factor of ringing signal (≈ 1.25) RSLEW, CSLEW Ring waveform rise time ≈ 0.214 • (RSLEW • CSLEW) ≈ tr. For a 1.25 crest factor @ 20 Hz, tr ≈ 10 mS. ∴ (RSLEW = 150 kΩ, CSLEW = 0.33 µF.) CSLEW should be changed if a different crest factor is desired. Ringing Reference (Input to RSLEW) 0 B(RING) A(TIP) Battery This is the best time for switching between RINGING and other states for minimizing detect switching transients. Figure 2. Ringing Waveforms A a RL IL SLIC RSN RDC2 b RDC1 B CDC RDC Feed current programmed by RDC1 and RDC2 Figure 3. Feed Programming Am79R70 Data Sheet 13 TEST CIRCUITS A(TIP) VTX RL 2 SLIC VAB VL AGND RL RT RRX 2 B(RING) RSN IL2-4 = 20 log (VTX / VAB) A. Two- to Four-Wire Insertion Loss A(TIP) VTX SLIC VAB RL AGND RT RRX B(RING) RSN VRX IL4-2 = 20 log (VAB / VRX) BRS = 20 log (VTX / VRX) B. Four- to Two-Wire Insertion Loss and Four- to Four-Wire Balance Return Signal 1 ωC A(TIP) << RL RL S1 C SLIC 2 VL VL VTX VAB AGND RT RL S2 2 B(RING) RSN S2 Open, S1 Closed L-T Long. Bal. = 20 log (VAB / VL) S2 Closed, S1 Open 4-L Long. Sig. Gen. = 20 log (VL / VRX) L-4 Long. Bal. = 20 log (VTX / VL) C. Longitudinal Balance 14 Am79R70 Data Sheet RRX VRX TEST CIRCUITS (continued) ZD A(TIP) R VTX RT1 SLIC VS VM AGND R ZIN CT1 RT2 B(RING) RSN RRX ZD: The desired impedance; e.g., the characteristic impedance of the line Return loss = –20 log (2 VM / VS) D. Two-Wire Return Loss Test Circuit VCC 6.2 kΩ A(TIP) A(TIP) DET RL = 600 Ω B(RING) 15 pF RG B(RING) E1 F. Ground-Key Switching E. Loop-Detector Switching L1 200 Ω C1 RF1 50 Ω A RF2 50 Ω 200 Ω HF GEN 1.5 Vrms 80% Amplitude Modulated 100 kHz to 30 MHz CAX 33 nF B 50 Ω L2 C2 CBX 33 nF VTX SLIC under test G. RFI Test Circuit Am79R70 Data Sheet 15 TEST CIRCUITS (continued) +5 V –5 V CRT 1.5 µF RRT2 12 kΩ RRT1 430 kΩ RTRIP1 RTRIP2 CAX 2.2 nF A(TIP) HPA A(TIP) CHP VCC VNEG RD RSGH RSGL VTX HPB B(RING) VTX RRX 300 kΩ VRX RDC RYOUT1 RSGL open RSN RDC1 80 kΩ CBX 2.2 nF RSGH open RT 300 kΩ 18 nF B(RING) RD 75 kΩ RDC2 20 kΩ RDCR RDCR 2.0 kΩ RYOUT2 CDC 1.2 µF RYE D1 BAT1 VBAT1 D2 0.1 µF VBAT2 BAT2 0.1 µF BGND B2EN C1 C2 C3 D1 D2 E1 DET RSLEW 100 kΩ RINGIN AGND/ DGND See Note. CSLEW 0.33 µF BATTERY GROUND ANALOG GROUND Note: The input should be 50% duty cycle CMOS-compatible input. DIGITAL GROUND H. Am79R70 Test Circuit 16 Am79R70 Data Sheet APPLICATION CIRCUIT +5 V –5 V CRT 1.5 µF K1 Bat1 RRT1 515 kΩ A(TIP) K1 G TISP A 61089 A RING RFB = 50 Ω RTRIP2 CAX = 2.2 nF RFA = 50 Ω TIP RTRIP1 RRT2 12 kΩ K2 CHP 18 nF K2 VCC VNEG RD RSGH RSGL VTX RD 66 kΩ RSGH open RT1 125 kΩ HPA HPB RSN RT2 CBX = 2.2 nF VRX RDC2 50 kΩ RDC RYOUT1 CDC 820 nF CDCR RDCR1 RDCR 15 kΩ RYOUT2 RYE D1 BAT1 VBAT1 D2 0.1 µF BAT2 VBAT2 0.1 µF B2EN C1 C2 C3 D1 D2 E1 RSLEW 150 kΩ See Note. RINGIN AGND/ DGND Assumptions: 1. 1.25 CF 2. 25 mA ILOOP 3. 100 mA Ringing Current Limit RDCR2 15 kΩ 10 nF DET BGND VTX RRX 125 kΩ 250 kΩ CT RDC1 50 kΩ B(RING) RSGL open CSLEW 0.33 µF 4. 5.2 kΩ High Battery Loop Threshold 5. 925 Ω Ringing Loop Threshold 6. 600 Ω Two-wire Impedance, 600 Ω ZL Note: 7. G42L = 1 8. –67 V Vbat1, –24 V Vbat2 BATTERY GROUND ANALOG GROUND DIGITAL GROUND The input should be 50% duty cycle CMOS-compatible input. I. Application Circuit Am79R70 Data Sheet 17 PHYSICAL DIMENSIONS PL032 .485 .495 .447 .453 .009 .015 .585 .595 .042 .056 .125 .140 Pin 1 I.D. .080 .095 .547 .553 SEATING PLANE .400 REF. .490 .530 .013 .021 .050 REF. .026 .032 TOP VIEW 16-038FPO-5 PL 032 DA79 6-28-94 ae SIDE VIEW SOW28 28 15 .453 .500 .324 .350 0° 8° 1 .016 .050 14 .050 BSC DETAIL A .697 .728 0.86 0.90 .080 .100 .006 .0125 .002 .014 0.14 0.20 .014 .024 0.045 MIN. 16-038-SO28-2_AC SOW28 DF87 9-3-97 lv DETAIL A 18 Am79R70 Data Sheet REVISION SUMMARY Revision A to Revision B • Minor changes were made to the data sheet style and format to conform to Legerity standards. Revision B to Revision C • The 28-pin SOIC information and package was added to the Ordering Information and the Connection Diagrams sections. • The physical dimensions (PL032 and SOW28) were added to the Physical Dimensions section. • Updated the Pin Description table to correct inconsistencies. Revision C to Revision D • Changed Ring-Trip Components equation from: V BAT1 R RT1 = 300 • CF • ------------------------------------------------------------------------------------------------------------------------------------------ • ( R LRT + 150 + 2RF ) Vbat – 3.5 – ( 15 µA • 300 • CF • ( R LRT + 150 + 2R F ) ) To: V BAT1 R RT1 = 320 • CF • ------------------------------------------------------------------------------------------------------------------------------------- • ( R LRT + 150 + 2R F ) Vbat – 5 – ( 24 µA • 320 • CF • ( R LRT + 150 + 2R F ) ) Am79r70 Data Sheet 19 Notes: www.legerity.com Notes: www.legerity.com Legerity provides silicon solutions that enhance the performance, speeds time-to-market, and lowers the system cost of our customers' products. 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