LA8638V

Ordering number : EN5776 Monolithic Linear IC LA8638V Low-voltage Compander IC for Cordless Telephones Overview The LA8638V provides dynamic range expansion, noise suppression for enhancing the quality of audio signals in cordless telephones and other communications systems. This single chip provides the functions that make it ideal for cordless telephones: a compressor with a logarithmic compression ratio of 1/2, expander with a logarithmic expansion ratio of 2, splatter filter, microphone amplifier, BTL amplifier, waveform shaper for the receiving signal, muting for both receiving and transmitting signals, and standby operation. speaker with a load of 2 kΩ • Standby operation that conserves battery power during intermittent reception by disabling all but the waveform shaper for the receiving signal • Built-in splatter filter with user-specified fc • Low-voltage operation (1.8 V to 5.5 V) Package Dimensions unit: mm 3191-SSOP30 [LA8638V] Functions • Transmitter circuits: compressor, microphone amplifier, limiter (IDC), muting, output level changes to userspecified levels, and splatter filter • Receiver circuits: expander, buffer amplifier for filters, muting, output level changes to user-specified levels, and BTL amplifier • Other circuits: waveform shaper for the receiving signal and standby operation Features • Full processing of baseband signals for both receiving and transmitting signals • Built-in BTL receiver amplifier for driving a ceramic SANYO: SSOP30 Specifications Maximum Ratings at Ta = 25°C Parameter Maximum power supply voltage Maximum power dissipation Operating temperature Storage temperature Symbol VCC max Pd max Topr Tstg Ta ≤ 75°C Conditions Ratings 7.0 100 –20 to +75 –40 to +125 Unit V mW °C °C Operating Conditions at Ta = 25°C Parameter Recommended power supply voltage Operating power supply voltage range Symbol VCC VCCop Conditions Ratings 2.4 1.8 to 5.5 Unit V V SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110-8534 JAPAN 40398RM (OT) No. 5776-1/16 LA8638V Electrical Characteristics at Ta = 25°C, VCC = 2.4 V, fIN = 1 kHz Parameter Current drain with no signal Standby current Symbol ICCO ISTBY VOc GCc GEc THDc VNOc VLT VG max Lalt ATTc CTc fIN = 5 kHz; fifth-order Butterworth function filter (fc = 3.35 kHz) VIN = +30 dB, 1 kHz BPF RX—VIN = –10 dBV, 1 kHz BPF VIN = Vinrefe = 0 dB VIN = 0 dB VIN = –30 dB Rg = 620 Ω, f = 20 to 20 kHz VIN = +10 dB, 1 kHz BPF TX—VIN = –40 dBV, 1 kHz BPF THD = 3% VIN = –5 dBV 43 –39.0 2.2 3.2 –18.8 6.0 –1.5 No signal Standby mode, No signal Conditions Ratings min 3.0 0.4 typ 5.4 0.7 max 7.6 0.95 Unit mA mA [Transmitter block] Vinrefc = –60 dBV = 0 dB, microphone amplifier gain = 40 dB, RL = 15 kΩ Output level Gain change level Gain error Total harmonic distortion Output noise voltage Limiting voltage Microphone amplifier maximum voltage gain Low pass filter attenuation Muting attenuation Crosstalk level VIN = Vinrefc = 0 dB VIN = –10 dB VIN = –40 dB VIN = 0 dB Rg = 620Ω, f = 20 to 20 kHz VIN = +30 dB, 1 kHz BPF 0.88 40 12.0 –18.1 3.5 –2.0 –16.1 4.0 –0.7 0.45 1.8 1.05 46 16.5 –83 –61 25.0 –65 –50 –14.1 4.4 +1.0 1.0 4.5 1.23 dBV dB dB % mVrms Vp-p dB dB dBV dBV [Receiver block] Vinrefe = –20 dBV = 0 dB, RL = 15 kΩ Output level Gain change level Gain error Output noise voltage Muting attenuation Crosstalk level [BTL amplifier] RL = 2 kΩ Maximum output voltage Total harmonic distortion [Data shaper] VIN = –20 dBV, RL = 100 kΩ Duty factor Dead zone Output “H” level Output “L” level [Digital input characteristics] Input “H” level 1 Input “L” level 1 Input “H” level 2 Input “L” level 2 VIH1 VIL2 VIH2 VIL2 Pins 17, 18, 20, and 22 Pins 17, 18, 20, and 22 Pin 19 Pin 19 1.3 0.3 0.6 VCC 0.25 VCC V V V V DUTY UNSN VH VL 50 –34.5 2.38 0.12 0.3 57 –30.0 % dBV V V VObtl THDbtl 4.2 0.4 1.0 Vp-p % VOe GCe GEe VNOe ATTe CTe –16.3 7.1 +0.3 50 –100 –83 –13.8 8.4 +2.0 100 –80 –65 dBV dB dB µVrms dBV dBV No. 5776-2/16 LA8638V Block Diagram No. 5776-3/16 LA8638V Sample Application Circuit No. 5776-4/16 LA8638V Test Circuit No. 5776-5/16 LA8638V Usage Notes 1. Internal Reference Voltages The chip uses the following reference voltages internally. Pin 29 (VREF) Power supply voltage follower (approximately 0.5 VCC) Pin 4 (VREF2) Fixed voltage (approximately 1.25 V) 2. Microphone Amplifier Do not use the microphone amplifier as a buffer amplifier (non-reversing, zero-gain amplifier) because it is designed for high-gain operation—that is, gains above 6 dB—and is susceptible to oscillation below that level. For proper circuit balance, use the same resistance value for the bias resistor (between pins 28 and 29) and the feedback resistor (between pins 26 and 27). 3. BTL Amplifier The built-in BTL amplifier is designed for ceramic speakers only. Do not use it to drive a dynamic speaker. 4. Receiver Input Filter The receiver input filter uses external capacitors and resistors to determine the cutoff frequencies. The external circuit constants may be easily derived from the standardized circuit constants. Start by making all resistors the same size and determine the capacitances required to achieve the desired cutoff frequencies from the circuit constants in Table 1. Then, because capacitors are not available for such precise values, choose the closest ones available and then finetune the resistances. (As a result, the final resistances will not necessarily be equal.) Once the filter constants have been established, choose the bias voltage supply resistor RB so that the total DC resistance between pins 4 and 5 is on the order of 120 kΩ to standardize the voltage drop across this path due to the small base current from the transistor in the pin 5 input circuit and thus the duty factor for the data shaper at the next stage. Table 1. Standardized Circuit Constants Lowpass filter type Second-order Butterworth function Third-order Butterworth function Second-order Bessel function Third-order Bessel function X1 0.7071 0.2025 0.5000 0.1451 X2 1.4142 3.5468 0.6667 0.8136 X3 — 1.3926 — 0.5647 The Bessel functions for cutoff frequencies do not incorporate the notion of 3dB attenuation. The 3-dB attenuation frequency for the second-order function is 1.38 fc; for the third-order function, 1.75 fc. 5. Splatter Filter Cutoff Frequency The resistance between pin 24 and ground determines the cutoff frequency for the splatter filter in the transmitter circuit. (See Graph 1 on p. 8.) To fine-tune this frequency, use two resistors and adjust them to achieve the desired frequency. 6. Gain Change Levels The resistance between pins 29 and 30 determines the gain change level for the transmitter circuits. (See Graph 2 on p. 8.) The resistance between pin 9 and ground determines the gain change level for the receiver circuits. (See Graph 3 on p. 8.) No. 5776-6/16 LA8638V 7. Protective Diodes Preventing Static Breakdown The control pins and data output pins have had their upper protective diodes removed so as to permit direct connection to a microcomputer. No protective diodes: VCC (pin 15), GND (pins 1 and 12) Lower protective diodes only: Pins 16 to 20, 22 Both upper and lower protective diodes: All other pins 8. Preemphasis and Deemphasis This chip provides preemphasis in the microphone amplifier and deemphasis in the BTL amplifier's input stage. The amount depends on the CR time constants for the filters on the corresponding pins—the primary high pass filter on the microphone amplifier's positive (pin 28) or negative (pin 27) input for preemphasis and the primary low pass filter between pins 10 and 11 for deemphasis. 9. Full-Wave Rectifier Smoothing Capacitors The external capacitors on pins 8 and 25 are for the full-wave rectifiers for the expander and compressor. They not only smooth the output but also determine the time constant for the transient characteristics. This time constant is the product of the capacitance and 15 kΩ, the input resistance of the full-wave rectifier. Although there is a tendency to lower the time constant for the expander to reduce noise at the ends of words, the designer must keep in mind that such cuts reduce the amount of smoothing and thus raise the risk of distortion. 10. Compressor's Summing Amplifier Achieving a DC gain of 1 and an AC gain of infinity from the compressor's summing amplifier requires suppressing AC feedback with the capacitor on pin 3. The cutoff frequency is determined by the product of its capacitance and the internal resistance of 22.5 kΩ. 11. Standby Function The chip's standby function does not produce a total shutdown of all circuits. It disables the audio signal processing block, but leaves the waveform shaper block for the receiving signal operating. For this reason, it is not possible to connect the battery directly to the power supply pin (pin 15). There must be an intervening transistor switch for an intermittent power supply. 12. Control Modes Pin 17 SUB-CNT1 OPEN/HIGH OPEN/HIGH LOW LOW Pin Number Pin 19 Pin 20 Pin 22 Pin 18 SUB-CNT2 OPEN/HIGH LOW OPEN/HIGH LOW Pin Name BTL-CNT TX-MUTE TX-LVL-CNT Mode Standby Receiver muted Normal receiver output levels Low receiver output levels OPEN/HIGH BTL amplifier disabled Transmitter muted Normal transmitter output levels LOW BTL amplifier enabled Transmitter enabled High transmitter output levels Note: The standby mode overrides all other mode settings. No. 5776-7/16 LA8638V Graph 1. Splatter Filter Cutoff Frequency vs. External Resistance Graph 2. Transmitter Gain Change Level vs. External Resistance Cutoff frequency (kHz) External resistance (kΩ) Graph 3. Receiver Gain Change Level vs. External Resistance Level difference (dB) External resistance (kΩ) Level difference (dB) External resistance (kΩ) No. 5776-8/16 LA8638V Pin Descriptions Pin Number 1 Pin Name GND Pin Voltage Equivalent Circuit Description Ground for all circuits except BTL amplifier 2 1/2 VCC VCC/2 Resistance voltage divider pin 29 VREF VCC/2 Reference voltage for all circuits except receiver block 3 CMP-NF VCC/2 AC feedback control for compressor's summing amplifier DC gain: 1 AC gain: Infinite 4 DT-VREF 1.25 V Reference voltage for receiver block This supplies the bias voltage for pin 5. 5 RX-IN 1.25 V power supply Filter buffer input 6 RX-FIL-OUT 1.25 V Filter buffer output 7 EXP-IN VCC/2 Expander input. Voltage-current converter input. Full-wave rectifier input. 8 EXP-RCT Indeterminate (when there is no signal) Full-wave rectifier output for expander block (AC smoothing) 9 RX-ATT-ADJ 0.03 V Pin for setting attenuation for receiver output level switching 10 RX-OUT VCC/2 Receiver block output Continued on next page. No. 5776-9/16 LA8638V Continued from preceding page. Pin Number 12 Pin Name BTL-GND Pin Voltage Equivalent Circuit Description Ground for BTL amplifier 11 BTL-IN VCC/2 BTL amplifier input 13 BTL-OUT1 VCC/2 BTL amplifier reversed output 14 BTL-OUT2 VCC/2 BTL amplifier non-reversed output 15 VCC Power supply pin 16 FSK-OUT Indeterminate (when there is no signal) Comparator output (open collector output) 17 18 20 22 SUB-CNT1 SUB-CNT2 TX-MUTE TX-LVL-CNT VCC VCC VCC VCC Internal operating mode control pins. All four have identical structures. 19 BTL-CNT VCC + 0.65 ————— 2 BTL amplifier operation control pins 21 TX-DATA-IN VCC /1.6 Transmitter data input 23 TX-OUT VCC /1.6 Transmitter output 24 FREQ-ADJ 0.01 V Pin for setting cutoff frequency of splatter filter Continued on next page. No. 5776-10/16 LA8638V Continued from preceding page. Pin Number Pin Name Pin Voltage Equivalent Circuit Description 25 CMP-RCT Indeterminate (when there is no signal) Full-wave rectifier output for compressor block (AC smoothing) 26 27 28 MIC-OUT MIC-IN2 MIC-IN1 VCC/2 VCC/2 VCC/2 power supply Microphone amplifier output Microphone amplifier negative input Microphone amplifier positive input 30 TX-LVL-ADj VCC/2 Pin for setting amplification for transmitter output level switching I/O Characteristics Crosstalk Characteristics Output level, VO — dBV O UT TX -O (p U pi T( n2 in 23 3) Crosstalk level, CT — dBV RX → TX (pin 23) ) TX-MUT E (pin 23 ) TX -D -OU T( pin 10) T- TX → RX (pin 10) RX RX-MUTE (pin 10) Input level, VIN — dBV Splatter Filter Frequency Characteristics VCC = 2.4 V; resistance Input level, VIN — dBV Current Drain —. VCC BTL on Current drain, ICC — mA Response — dB BTL off Standby Frequency, f — kHz Power supply voltage, VCC — V No. 5776-11/16 LA8638V Output Level — VCC Gain Change Level Difference — VCC TX (pin 23) ← VIN = –60 dBV RX (pin 10) ← VIN = –20 dBV Gain change level difference, GC — dB Output level, VO — dBV Switches gain between high and low levels. Resistance at pin 9: 1 kΩ; Resistance between pins 30 and 29: 4.7 kΩ Power Supply Voltage, — VCC V Compander Gain Error — VCC Power supply voltage, VCC — V Output Distortion — VCC Total harmonic distortion, THD — % Compander gain error, GE — dB RX (pin 10) ← VIN = –20 dBV TX (pin 23) ← VIN = –60 dBV TX-DATA (pin 23) ← VIN = –20 dBV Power supply voltage, VCC — V BTL Power Amplifier Maximum Output Voltage — VCC Power supply voltage, VCC — V Receiver Muting Attenuation — VCC Maximum output voltage, VO — Vp-p Muting level — dBV Pins 13 and 14 Pin 10 Power supply voltage, VCC — V Receiver (TX → RX) Crosstalk — VCC 1 kHz-BPF TX-IN(28 pin): VIN = –40dBV Power supply voltage, VCC — V Transmitter Crosstalk — VCC Crosstalk level, CT — dBV Pin 13 Pin 10 Pin 14 Power supply voltage, VCC — V Crosstalk level, CT — dBV Power supply voltage, VCC — V No. 5776-12/16 LA8638V Output Noise Level — VCC Splatter Filter Cutoff Frequency — VCC Att. = 3 dB down; resistance at pin 24 = 4.3 kΩ Output noise level — dBV TX (pin 23) TX (pin 23) Power supply voltage, VCC — V Splatter Filter Attenuation — VCC fIN = 5 or 1 kHz; resistance at pin 24 = 4.3 kΩ Cutoff frequency — kHz TX (pin 23) Power supply voltage, VCC — V Data Shaper Duty Cycle — VCC Attenuation — dB Power supply voltage, VCC — V Data Shaper Dead Zone — VCC No signal Duty cycle — % Power supply voltage, VCC — V Current Drain — Ta BTL on Minimum input level — dBV Current drain, ICC — mA BTL off Standby Power supply voltage, VCC — V Output Level — Ta Ambient temperature, Ta — °C Gain Change Level Difference — Ta RX (pin 10) ← VIN = –20 dBV TX (pin 23) ← VIN = –60 dBV Gain change level difference, GC — dB Output level, VO — dBV TX-DATA (pin 23) ← VIN = –20 dBV Switches gain between high and low levels. Resistance at pin 9: 1 kΩ; Resistance between pins 30 and 29: 4.7 kΩ Ambient temperature, Ta — °C Ambient temperature, Ta — °C No. 5776-13/16 LA8638V Compander Gain Error — Temperature Output Distortion — Temperature Total harmonic distortion, THD — % Compander gain error, GE — dB TX (pin 23) ← V{IN} = –60 dBV RX (pin 10) ← V{IN} = –20 dBV Ambient temperature, Ta — °C BTL Distortion — Temperature Ambient temperature, Ta — °C BTL Power Amplifier Maximum Output Voltage — Temperature THD output = 1 % Total harmonic distortion, THD — % Pin 13 Pin 14 Ambient temperature, Ta — °C BTL Output Level — Temperature Maximum output voltage, VO — VPP Ambient temperature, Ta — °C Receiver Muting Attenuation — Temperature Pin 14 Output level, VO — dBV Muting level — dBV Pin 13 Pin 13 Pin 14 Pin 10 Ambient temperature, Ta — °C Receiver (TX → RX) Crosstalk — Temperature Ambient temperature, Ta — °C Transmitter Crosstalk — Temperature Crosstalk level, CT — dBV Pin 13 Pin 10 Pin 14 Ambient temperature, Ta — °C Crosstalk level, CT — dBV Ambient temperature, Ta — °C No. 5776-14/16 LA8638V Output Noise Level — Temperature Splatter Filter Cutoff Frequency — Temperature Att. = 3 dB down; resistance at pin 24 = 4.3 kΩ Output noise level — dBV TX (pin 23) TX-MUTE (pin 23) RX (pin 10) RX-MUTE (pin 10) Ambient temperature, Ta — °C Splatter Filter Attenuation — Temperature Cutoff frequency — kHz Ambient temperature, Ta — °C Receiver Maximum Input Level — Temperature Ambient temperature, Ta — °C Transmitter Maximum Input Level — Temperature THD = 1% for output from pin 23 Maximum inputlevel at pin 5 — dBV THD = 1% for output from pin 10 Attenuation — dB Ambient temperature, Ta — °C Data Shaper Duty Cycle — Temperature Maximum input level at pin 21 — dBV Ambient temperature, Ta — °C Data Shaper Dead Zone — Temperature Duty cycle — % Ambient temperature, Ta — °C Minimum input level — dBV Ambient temperature, Ta — °C No. 5776-15/16 LA8638V s No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of which may directly or indirectly cause injury, death or property loss. s Anyone purchasing any products described or contained herein for an above-mentioned use shall: Œ Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and expenses associated with such use:  Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees jointly or severally. s Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of intellectual property rights or other rights of third parties. This catalog provides information as of April, 1998. Specifications and information herein are subject to change without notice. PS No. 5776-16/16