U4083B ATMEL | Alldatasheet

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Technical content

Features

  • Wide Operating Voltage Range: 2V to 16V  Low Current Consumption: 2.7 mA Typically  Chip Disable Input to Power Down the Integrated Circuit  Low Power-down Quiescent Current  Drives a Wide Range of Speaker Loads  Output Power Po = 250 mW at RL = 32Ω (Speaker)  Low Harmonic Distortion (0.5% Typically)  Wide Gain Range: 0 dB to 46 dB Benefits  Low Number of External Components  Low Current Consumption 1. Description The integrated circuit U4083B is a low-power audio amplifier for telephone loudspeak- ers. It has differential s peaker outputs to maximize th e output swing at low supply voltages. There is no need for coupler capacitors. The U4083B has an open-loop gain of 80 dB where the closed-loop gain is adjusted with two external resistors. A chip dis- able pin permits powering down and/or muting the input signal. Figure 1-1. Block Diagram Bias circuitU4083B 4k 4k 50k 50k 125k Amp1 Amp2 FC2 FC3 Vi VS VO1 VO2 CD GND Low-power Audio Amplifier for Telephone

Applications

Rev. 4655C–CORD–03/06

4655C–CORD–03/06 U4083B 2. Pin Configuration Figure 2-1. Pinning SO8 i FC1 FC2 GND CD VO1 VO2 VS Table 2-1. Pin Description Pin Symbol Function

1 CD Chip disable

2 FC2 Filtering, power supply rejection

3 FC1 Filtering, power supply rejection

5 VO1 Amplifier output 1

7 GND Ground

8 VO2 Amplifier output 2

4655C–CORD–03/06 U4083B 3. Functional Description Including External Circuitry

3.1 Pin 1: Chip Disable Digital Input (CD)

Pin 1 (chip disable) is used to power down the IC to conserve power or mute the IC or both. Input impedance at Pin 1 is typically 90 kΩ.  Logic 0 < 0.8V IC enabled (normal operation)  Logic 1 > 2V IC disabled Figure 8-15 on page 12 shows the power supply current diagram. The change in differential gain from normal operation to muted operation (muting) is more than 70 dB. Switching characteristics are as follows:  Turn-on time ton = 12 ms to 15 ms  Turn-off time toff ≤ 2 µs They are independent of C1, C2 and VS. Voltages at Pins 2 and 3 are supplied from V S and, therefore, do not change when the U4083B is disabled. The outputs, V O1 (Pin 5) and V O2 (Pin 8), turn to a high impedance condition by removing the signal from the speaker. When signals are applied from an external source to the outputs (disabled), they must not exceed the range between the supply voltage, VS, and ground.

3.2 Pins 2 and 3: Filtering , Power Supply Rejection

Power supply rejection is provided by capacitors C1 and C2 at Pin 3 and Pin 2, respectively. C1 is dominant at high frequencies whereas C 2 is dominant at low frequencies ( Figure 8-4 on page 8 to Figure 8-7 on page 9). The values of C1 and C2 depend on the conditions of each application. For example, a line-powered speake rphone (telephone amplifier) will require more filtering than a system powered by regulated power supply. The amount of rejection is a function of the capacitors and the equivalent impedance at Pin 3 and Pin 2 (see electrical characteristic equivalent resistance, R). Apart from filtering, capacitors C 1 and C2 also influence the turn-on time of the circuit at power up, since the capacitors are charged up through the internal resistors (50 k Ω and 125 k Ω) as shown in the block diagram. Figure 8-1 on page 7 shows the turn-on time versus C2 at VS = 6V, for two different C1 values. The turn-on time is 60% longer when VS = 3V and 20% shorter when VS = 9V. The turn-off time is less than 10 µs.

4655C–CORD–03/06 U4083B

3.3 Pin 4: Amplifier Input V i, Pin 5: Amplifier Output 1 VO1, Pin 8: Amplifier Output 2 VO2

There are two identical operational amplif iers. Amplifier 1 has an open-loop gain ≥ 80 dB at 100Hz (Figure 8-2 on page 7), whereas the closed-loop gain is set by external resistors, R f and Ri (Figure 8-3 on page 8 ). The amplifier is unity gain stabl e, and has a unity gain frequency of approximately 1.5 MHz. A closed-loop gain of 46 dB is recommended for a frequency range of 300Hz to 3400Hz (voice band). Amplifier 2 is internally set to a gain of –1.0 dB (0 dB). The out- puts of both amplifiers are capable of sourcing and sinking a peak current of 200 mA. Output voltage swing is between 0.4V and V S – 1.3V at maximum current ( Figure 8-18 on page 13 and Figure 8-19 on page 13). The output DC offset voltage between Pins 5 and 8 (V O1 – VO2) is mainly a function of the feed- back resistor, Rf, because the input offset voltages of the two amplifiers neutralize each other. Bias current of Amplifier 1 which is constant with respect to V s, flows out of Pin 4 (V i) and through Rf, forcing VO1 to shift negative by an amount equal to RfIIB and VO2 positive to an equal amount. The output offset voltage specified in the electrical characteristics is measured with the feedback resistor (Rf = 75 kΩ) shown in the typical application circuit, Figure 8-20 on page 14. It takes into account the bias current as well as internal offset voltages of the amplifiers.

3.4 Pin 6: Supply and Power Dissipation

Power dissipation is shown in Figure 8-8 on page 9 to Figure 8-10 on page 10 for different loads. Distortion characteristics are given in Figure 8-11 on page 10 to Figure 8-13 on page 11. where Tjmax = Junction temperature = 140°C Tamb = Ambient temperature RthJA = Thermal resistance, junction-ambient Power dissipated within the IC in a given application is found from the following equation: P tot = (VS × IS) + (IRMS × VS) – (RL × IRMS IS is obtained from Figure 8-15 on page 12. IRMS is the RMS current at the load RL. The IC's operating range is defined by a pe ak operating load current of ±200 mA ( Figure 8-8 on page 9 to Figure 8-13 on page 11). It is further specified with respect to different loads (see Fig- ure 8-14 on page 12 ). The left (ascending) portion of each of the three curves is defined by the power level at which 10% distortion occurs. The center flat portion of each curve is defined by the maximum output current capability of the integrated circuit. The right (descending) portion of each curve is defined by the maximum internal power dissipation of the IC at 25°C. At higher ambient temperatures, the maximum load power must be reduced according to the above men- tioned equation. P totmax Tjmax Tamb– RthJA

4655C–CORD–03/06 U4083B

3.5 Layout Considerations

Normally, a snubber is not needed at the output of the IC, unlike many other audio amplifiers. However, the PC-board layout, stray capacitanc es, and the manner in which the speaker wires are configured may dictate otherwise. Generally, the speaker wires should be twisted tightly, and should not be more than a few cm (or inches) in length. 4. Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Reference point pin 7, Tamb = 25° C unless otherwise specified. Parameters Symbol Value Unit Supply voltage Pin 6 V S –1.0 to +18 V Voltages Disabled Pins 1, 2, 3 and 4 Pins 5 and 8 –1.0 to (VS + 1.0) –1.0 to (VS + 1.0) V V Output current Pins 5 and 8 ±250 mA Junction temperature T j +140 °C Storage temperature range T stg –55 to +150 °C Ambient temperature range T amb –20 to +70 °C Power dissipation SO8: Tamb = 60°C P tot 440 mW 5. Thermal Resistance Parameters Symbol Value Unit Junction ambient SO8 R thJA 180 K/W 6. Recommended Operating Conditions Parameters Symbol Value Unit Supply voltage Pin 6 V S 2 to 16 V Load impedance Pins 5 to 8 R L 8.0 to 100 Ω Load current I L ±200 mA Differential gain (5.0 kHz bandwidth) DG 0 to 46 dB Voltage at CD Pin 1 V CD VS V Ambient temperature range T amb –20 to +70 °C

4655C–CORD–03/06 U4083B 7. Electrical Characteristics Tamb = +25°C, reference point pin 7, unless otherwise specified Parameters Test Conditions Symbol Min. Typ. Max. Unit Amplifiers (AC Characteristics) Open-loop gain (Amplifier 1, f < 100Hz) GVOL1 80 dB Closed-loop gain (Amplifier 2) V S = 6.0V, f = 1.0 kHz, RL = 32Ω GV2 –0.35 0 +0.35 dB Gain bandwidth product G BW 1.5 MHz Output power VS = 3.0V, RL = 16Ω, d < 10% VS = 6.0V, RL = 32Ω, d < 10% VS = 12V, RL = 100Ω, d < 10% PO PO PO 250 400 mW Total harmonic distortion (f = 1.0 kHz) VS = 6.0V, RL = 32Ω, Po = 125 mW VS > 3.0V, RL = 8Ω, Po = 20 mW VS > 12V, RL = 32Ω, Po = 200 mW d d d 0.5 0.5 0.6 1.0 % Power supply rejection ratio VS = 6.0V, ∆VS = 3.0V C1 = α, C2 = 0.01 µF C1 = 0.1 µF , C2 = 0, f = 1.0 kHz C1 = 1.0 µF , C2 = 5.0 µF , f = 1.0 kHz PSRR PSRR PSRR 50 12 dB Muting VS = 6.0V, 1.0 kHz < f < 20 kHz, CD = 2.0V G MUTE >70 dB Amplifiers (DC Characteristics) Output DC level at VO1, VO2 Rf = 75 kW VS = 3.0V, RL = 16Ω VS = 6.0V VS = 12V VO VO VO 1.0 1.15 2.65 5.65 1.25 V Output high level I O = –75 mA, 2.0V < VS < 16V VOH VS – 1 V Output low level I O = –75 mA, 2.0V < VS < 16V VOL 0.16 V Output DC offset voltage (VO1 – VO2) VS = 6.0V, Rf = 75 kΩ, RL = 32Ω∆ VO –30 0 +30 mV Input bias current at Vi VS = 6.0V –I IB 100 200 nA Equivalent resistance at Pin 3 V S = 6.0V R 100 150 220 k Ω Equivalent resistance at Pin 2 V S = 6.0V R 18 25 40 k Ω Chip disable Pin 1 Input voltage low Input voltage high Input resistance VS = VCD = 16V VIL VIH RCD 2.0 50 90 0.8 175 V V kΩ Power supply current VS = 3.0V, RL = α, CD = 0.8V VS = 16V, RL = α, CD = 0.8V VS = 3.0V, RL = α, CD = 2.0V IS IS IS 65 4.0 5.0 100 mA mA µA

4655C–CORD–03/06 U4083B Figure 8-14. Maximum Allowable Load Power Figure 8-15. Power-supply Current Figure 8-16. Small Signal Response 04 81 2 1 6 100 200 300 400 500 P L (W L VS (V) 600 RL = 32

16 Ohm

8 Ohm

Tamb = 25°C - Derate at higher temperature 04 81 2 1 6 IS (m VS (V) CD = 0 CD = VS RL = ∞ Output 20m V/Div Input 1m V/Div 20 µs/Div

4655C–CORD–03/06 U4083B Figure 8-20. Application Circuit Bias circuitU4083B 4k 4k 50k 50k 125k 100nF 10R Amp1 Amp2 100nF 10R 0.1µF 3k Ci Ri Rf75k 1µF 5µF FC2 FC3 Vi VS VO1 VO2 CD GND C1B C2B R1B R2B

4655C–CORD–03/06 U4083B 10. Package Information 9. Ordering Information Extended Type Number Package Remarks U4083B-MFPY SO8, Pb-free Tube U4083B-MFPG3Y SO8, Pb-free Taped and reeled technical drawings according to DIN specifications Dimensions in mm 5.00 4.85 0.4 1.27 3.81 1.4 0.25 0.10 5.2 4.8 3.7 3.8 6.15 5.85 0.2

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