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| a FEATURES Single-Supply Operation: 2.7 V to 6 V High Output Current: 100 mA Low Supply Current: 800 A/Amp Wide Bandwidth: 1 MHz Slew Rate: 2.2 V/ s No Phase Reversal Low Input Currents Unity Gain Stable APPLICATIONS Battery Powered Instrumentation Medical Remote Sensors ASIC Input or Output Amplifier Automotive GENERAL DESCRIPTION CMOS Single-Supply Rail-to-Rail Input/Output Operational Amplifiers OP250/OP450 PIN CONFIGURATIONS 8-Lead Narrow Body SO (SO-8) OUT A -IN A +IN A V- 1 2 8 V+ OUT B -IN B +IN B OP250 7 3 (Not to Scale) 6 4 5 8-Lead TSSOP (RU-8) OUT A -IN A +IN A V- 1 8 OP250 4 5 V+ OUT B -IN B +IN B The OP250 and OP450 are dual and quad CMOS single-supply, amplifiers featuring rail-to-rail inputs and outputs. Both are guaranteed to operate from a +2.7 V to +5 V single supply. These amplifiers have very low input bias currents. Outputs are capable of driving 100 mA loads and are stable with capacitive loads. Supply current is less than 1 mA per amplifier. Applications for these amplifiers include portable medical equipment, safety and security, and interface to transducers with high output impedance. The ability to swing rail-to-rail at both the input and output enables designers to build multistage filters in single-supply systems and maintain high signal-to-noise ratios. The OP250 and OP450 are specified over the extended industrial (-40C to +125C) temperature range. The OP250, dual, is available in 8-lead TSSOP and SO surface mount packages. The OP450, quad, is available in 14-lead thin shrink small outline (TSSOP) and narrow 14-lead SO packages. 14-Lead Narrow Body SO (N-14) OUT A -IN A +IN A V+ +IN B -IN B OUT B 1 2 3 4 5 6 7 14 13 12 OUT D -IN D +IN D V- +IN C -IN C OUT C OP450 (Not to Scale) 11 10 9 8 14-Lead TSSOP (RU-14) OUT A -IN A +IN A V+ +IN B -IN B OUT B 1 14 AD8532 OP450 7 8 OUT D -IN D +IN D V- +IN C -IN C OUT C REV. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 (c) Analog Devices, Inc., 1997 OP250/OP450-SPECIFICATIONS ELECTRICAL CHARACTERISTICS (V = S 3.0 V, TA = 25 C, VCM = 1.5 V unless otherwise noted) Min Typ Max 8 20 40 60 500 25 60 3 Units mV mV pA pA pA pA pA V dB dB V/mV V/C pA/C pA/C V V V mV mV mV mA dB dB A A V/s s MHz Degrees dB V p-p nV/Hz nV/Hz pA/Hz Parameter INPUT CHARACTERISTICS Offset Voltage Input Bias Current Symbol VOS Conditions -40C < TA < +125C IB -40C < TA < +85C -40C < TA < +125C Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift Bias Current Drift Offset Current Drift OUTPUT CHARACTERISTICS Output Voltage High IOS -40C < TA < +125C CMRR AVO VOS/T IB/T IOS/T VOH VOL IOUT ZOUT PSRR ISY VCM = 0 V to 3 V -40C < TA < +125C RL = 2 k , VO = 0.3 V to 2.7 V 0 40 35 55 800 10 1.8 0.07 2.99 2.94 1 55 100 180 60 55 80 700 0.5 2 Output Voltage Low IL = 100 A IL = 10 mA -40C to +125C IL = 100 A IL = 10 mA -40C to +125C f = 1 MHz, AV = 1 VS = 2.7 V to 6 V -40C < TA < +125C VO = 0 V -40C < TA < +125C RL = 10 k To 0.01% 2.85 2.8 100 125 Output Current Open Loop Impedance POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Settling Time Gain Bandwidth Product Phase Margin Channel Separation NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density Specifications subject to change without notice. 1,000 1,250 SR tS GBP Oo CS en p-p en in f = 1 kHz, RL = 10 k 0.1 Hz to 10 Hz f = 1 kHz f = 10 kHz f = 1 kHz 1.9 4 0.95 46 100 10 45 30 0.05 -2- REV. 0 OP250/OP450 ELECTRICAL CHARACTERISTICS Parameter INPUT CHARACTERISTICS Offset Voltage Input Bias Current VOS -40C < TA < +125C IB -40C < TA < +85C -40C < TA < +125C Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift Bias Current Drift Offset Current Drift OUTPUT CHARACTERISTICS Output Voltage High IOS -40C < TA < +125C CMRR AVO VOS/T IB/T IOS/T VOH VOL IOUT ZOUT PSRR ISY VCM = 0 V to 5 V -40C < TA < +125C RL = 2 k , Vo = 0.3 V to 4.7 V -40C < TA < +125C 0 45 40 60 1,000 10 1.8 0.07 4.99 4.94 1 40 100 200 60 55 80 800 750 2.2 100 3 1 48 100 10 45 30 0.05 1,250 1,750 0.5 2 (VS = 5.0 V, TA = 25 C, VCM =2.5 V unless otherwise noted) Min Typ 2 Max 7.5 20 40 60 500 25 60 5 Units mV mV pA pA pA pA pA V dB dB V/mV V/C pA/C pA/C V V mV V mV mV mA dB dB A A V/s kHz s MHz Degrees dB V p-p nV/Hz nV/Hz pA/Hz Symbol Conditions Output Voltage Low IL = 100 A IL = 10 mA -40C to +125C IL = 100 A IL = 10 mA -40C to +125C f =1 MHz, AV = 1 VS = 2.7 V to 6 V -40C < TA < +125C VO = 0 V -40C < TA < +125C RL = 10 k 1% Distortion To 0.01% 4.9 100 125 Output Current Open Loop Impedance POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Full-Power Bandwidth Settling Time Gain Bandwidth Product Phase Margin Channel Separation NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density Specifications subject to change without notice. SR BWP tS GBP Oo CS en p-p en in f = 1 kHz, RL = 10 k 0.1 Hz to 10 Hz f = 1 kHz f = 10 kHz f = 1 kHz REV. 0 -3- OP250/OP450 ABSOLUTE MAXIMUM RATINGS 1, 2 Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6 V Input Voltage2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND to VS Common-Mode Input Voltage . . . . . . . . . . . . . . . . . . . . 6 V Output Short-Circuit Duration to GND . . . . . . . . . . . . . Observe Derating Curves ESD Susceptibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000 V Storage Temperature Range S, RU Package . . . . . . . . . . . . . . . . . . . . . 65C to +150C Operating Temperature Range OP250G/OP450G . . . . . . . . . . . . . . . . . . 40C to +125C Junction Temperature Range S, RU Package . . . . . . . . . . . . . . . . . . . . . 65C to +150C Lead Temperature Range (Soldering, 60 sec) . . . . . . . +300C NOTES 1 Absolute maximum ratings apply at +25C, unless otherwise noted. 2 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; the functional operation of the device at these or any other conditions above 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. Package Type 8-Lead SOIC (S) 8-Lead TSSOP (RU) 14-Lead SOIC (N) 14-Lead TSSOP (RU) * JA JC Units C/W C/W C/W C/W 158 240 120 180 43 43 36 35 *JA is specified for the worst case conditions, i.e., JA specified for device soldered in circuit board for surface mount packages. ORDERING GUIDE Model OP250GS OP250GRU OP450GS OP450GRU Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C Package Description 8-Lead SOIC 8-Lead TSSOP 14-Lead SOIC 14-Lead TSSOP Package Options SO-8 RU-8 N-14 RU-14 CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the OP250/OP450 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. WARNING! ESD SENSITIVE DEVICE -4- REV. 0 Typical Performance Characteristics-OP250/OP450 10k SUPPLY CURRENT / AMPLIFIER - mA 0.9 VS = +2.7V TA = +25 C TA = +25 C 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.75 1k OUTPUT VOLTAGE - mV SOURCE 100 SINK 10 1 0.1 0.001 0.01 0.1 1 LOAD CURRENT - mA 10 100 1 1.25 1.5 1.75 2 2.25 SUPPLY VOLTAGE - V 2.5 2.75 3 Figure 1. Output Voltage to Supply Rail vs. Load Current Figure 4. Supply Current per Amplifier vs. Supply Voltage 1k VS = +5V TA = +25 C OUTPUT VOLTAGE - mV 1 VS = +5V VCM = +2.5V INPUT OFFSET VOLTAGE - mV 100 SOURCE 0.5 SINK 10 0 -0.5 1 0.1 0.001 0.01 0.1 1 LOAD CURRENT - mA 10 100 -1 -55 -35 -15 -5 25 45 65 85 TEMPERATURE - C 105 125 145 Figure 2. Output Voltage to Supply Rail vs. Load Current Figure 5. Input Offset Voltage vs. Temperature 0.85 SUPPLY CURRENT / AMPLIFIER - mA 400 VS = +5V, +3V VCM = VS/2 0.8 INPUT BIAS CURRENT - pA VS = +5V 300 0.75 200 0.7 VS = +3V 100 0.65 -55 -35 -15 -5 25 45 65 85 TEMPERATURE - C 105 125 145 0 -55 -35 -15 -5 25 45 65 85 TEMPERATURE - C 105 125 145 Figure 3. Supply Current per Amplifier vs. Temperature Figure 6. Input Bias Current vs. Temperature REV. 0 -5- OP250/OP450-Typical Performance Characteristics 5 VS = +5V, +3V VCM = VS/2 INPUT OFFSET CURRENT - pA 80 60 40 20 0 -20 -40 VS = +5V RL = NO LOAD TA = +25 C 0 -45 -90 -135 -180 -225 -270 -315 -360 PHASE SHIFT - DEGREES 4 2 1 -60 0 -55 -80 1k -35 -15 -5 25 45 65 85 TEMPERATURE - C 105 125 145 GAIN - dB 3 10k 100k 1M FREQUENCY - Hz 10M 100M Figure 7. Input Offset Current vs. Temperature Figure 10. Open-Loop Gain and Phase 2 VS = +5V, +3V TA = +25 C INPUT BIAS CURRENT - pA 5 VS = +2.7V RL = 2 k VIN = 2.5 VP-P TA = +25 C 4 1 OUTPUT SWING - VP-P 3 2 0 1 -1 0 1 2 3 COMMON-MODE VOLTAGE - V 4 5 0 1 10 100 FREQUENCY - Hz 1k 10k Figure 8. Input Bias Current vs. Common-Mode Voltage Figure 11. Closed-Loop Output Voltage Swing vs. Frequency 80 60 40 20 0 -20 -40 -60 -80 1k VS = +2.7V RL = NO LOAD TA = +25 C 0 -45 5 VS = +5.0V RL = 2 k VIN = 4.9 VP-P TA = +25 C 4 -90 -135 -180 -225 -270 -315 -360 PHASE SHIFT - DEGREES OUTPUT SWING - VP-P GAIN - dB 3 2 1 10k 100k 1M FREQUENCY - Hz 10M 100M 0 1 10 100 FREQUENCY - Hz 1k 10k Figure 9. Open-Loop Gain and Phase Figure 12. Closed-Loop Output Voltage Swing vs. Frequency -6- REV. 0 OP250/OP450 400 350 300 250 IMPEDANCE - 200 150 100 50 0 1k 100 AV = +1 POWER SUPPLY REJECTION RATIO - dB VS = +5V RL = NO LOAD TA = +25 C VS = +5V TA = +25 C 80 60 +PSRR 40 -PSRR 20 AV = +10 10k 100k 1M FREQUENCY - Hz 10M 100M 0 100 1k 10k 100k FREQUENCY - Hz 1M 10M Figure 13. Closed-Loop Output Impedance vs. Frequency Figure 16. Power Supply Rejection vs. Frequency 80 70 VS = +5V TA = +25 C 70 60 50 VS = +2.7V RL = 2 k TA = +25 C -OS COMMON-MODE REJECTION - dB 60 50 40 30 20 10 0 -10 -20 1 10 100 FREQUENCY - Hz 1k 10k SMALL SIGNAL OVERSHOOT - % 40 30 20 +OS 10 0 10 100 CAPACITANCE - pF 1k Figure 14. Common-Mode Rejection vs. Frequency Figure 17. Small Signal Overshoot vs. Load Capacitance 100 POWER SUPPLY REJECTION RATIO - dB VS = +2.7V TA = +25 C SMALL SIGNAL OVERSHOOT - % 70 60 50 -OS 40 30 +OS 20 VS = +5.0V RL = 2 k TA = +25 C 80 60 40 -PSRR 20 +PSRR 0 10 0 10 -20 100 1k 10k 100k FREQUENCY - Hz 1M 10M 100 CAPACITANCE - pF 1k Figure 15. Power Supply Rejection vs. Frequency Figure 18. Small Signal Overshoot vs. Load Capacitance REV. 0 -7- OP250/OP450-Typical Performance Characteristics VS = 1.35V VIN = 50mV AV = 1 RL = 2k CL = 100pF TA = 25 C VS = 2.5V AV = 1 RL = 2k TA = 25 C 2s 25mV 2s 1V Figre 19. Small Signal Transient Response Figure 22. Large Signal Transient Response VS = 2.5V VIN = 50mV AV = 1 RL = 2k CL = 100pF TA = 25 C 2s 25mV 50s 1V Figure 20. Small Signal Transient Response Figure 23. No Phase Reversal 1 CURRENT NOISE DENSITY - pA/ VS = 1.35V AV = 1 RL = 2k TA = 25 C 0.1 2s 500mV 0.01 10 100 1k FREQUENCY - Hz 10k 100k Figure 21. Large Signal Transient Response Figure 24. Current Noise Density vs. Frequency -8- REV. 0 OP250/OP450 VS = 5V FREQUENCY = 10kHz TA = 25 C VS = 5V FREQUENCY = 1kHz TA = 25 C 30nV/ 200nV 45nV/ 100nV Figure 25. Voltage Noise Density vs. Frequency Figure 26. Voltage Noise Density vs. Frequency REV. 0 -9- OP250/OP450 THEORY OF OPERATION Output Phase Reversal The OPx50 family of amplifiers are CMOS rail-to-rail input and output single supply amplifiers designed for low cost and high output current drive. These features make the OPx50 op amps ideal for multimedia and telecom applications. Figure 27 shows the simplified schematic for an OPx50 amplifier. Two input differential pairs consisting of an n-channel pair (M1-M2) and a p-channel pair (M3-M4) provide a rail-to-rail input common-mode range. The outputs of the input differential pairs are combined in a compound folded-cascode stage, which drives the input to a second differential pair gain stage. The outputs of the second gain stage provide the gate voltage drive to the rail-to-rail output stage. The rail-to-rail output stage consists of M15 and M16, which are configured in a complementary common-source configuration. As with any rail-to-rail output amplifier, the gain of the output stage, and thus the open loop gain of the amplifier, is dependent on the load resistance. Also, the maximum output voltage swing is directly proportional to the load current. The difference between the maximum output voltage to the supply rails, known as the dropout voltage, is determined by the OPx50's output transistors' on-channel resistance. The output dropout voltage is given in Figures 1 and 2. Input Voltage Protection The OPx50 is immune to output voltage phase reversal with an input voltage within the supply voltages of the device. However, if either of the device's inputs exceeds 0.6 V outside of the supply rails, the output could exhibit phase reversal. This is due to the ESD protection diodes becoming forward biased, thus causing the polarity of the input terminals of the device to switch. The technique recommended in the Input Overvoltage Protection section should be applied in applications where the possibility of input voltages exceeding the supply voltages exists. Output Short Circuit Protection To achieve high quality rail-to-rail performance, the outputs of the OPx50 family are not short-circuit protected. Although these amplifiers are designed to sink or source as much as 250 mA of output current, shorting the output directly to ground could damage or destroy the device when excessive voltages or currents are applied. If to protect the output stage, the maximum output current should be limited to 250 mA. By placing a resistor in series with the output of the amplifier as shown in Figure 28, the output current can be limited. The minimum value for RX can be found from Equation 2. RX VSY 250 mA (2) Although not shown on the simplified schematic, there are ESD protection diodes connected from each input to each power supply rail. These diodes are normally reversed biased, but will turn on if either input voltage exceeds either supply rail by more than 0.6 V. Should this condition occur the input current should be limited to less than 5 mA. This can be done by placing a resistor in series with the input. The minimum resistor value should be: RIN VIN , MAX 5 mA (1) For a +5 V single supply application, RX should be at least 20 . Because RX is inside the feedback loop, VOUT is not affected. The trade-off in using RX is a slight reduction in output voltage swing under heavy output current loads. RX will also increase the effective output impedance of the amplifier to RO + RX, where RO is the output impedance of the device. VCC BIAS -VIN M1 M3 M4 M2 +VIN M5 VOUT BIAS M6 BIAS VEE Figure 27. OPx50 Simplified Schematic -10- REV. 0 OP250/OP450 +5V VIN RX 20 OP250 VOUT Figure 28. Output Short-Circuit Protection Power Dissipation Although the OPx50 family of amplifiers are able to provide load currents of up to 250 mA, proper attention should be given to not exceed the maximum junction temperature for the device. The equation for finding the junction temperature is given as: 500mV 1s TJ = PDISS x JA + TA (3) Where TJ = OPx50 junction temperature PDISS = OPx50 power dissipation JA = OPx50 junction-to-ambient thermal resistance of the package; and TA = The ambient temperature of the circuit Figure 30. Saturation Recovery from the Positive Rail In any application, the absolute maximum junction temperature must be limited to +150C. If this junction temperature is exceeded, the device could suffer premature failure. If the output voltage and output current are in phase, for example, with a purely resistive load, the power dissipated by the OPx50 can be found as: PDISS = I LOAD x VSY - VOUT Where ILOAD = OPx50 output load current VSY = OPx50 supply voltage; and VOUT = The output voltage ( ) (4) 500mV 1s Figure 31. Saturation Recovery from the Negative Rail Capacitive Loading By calculating the power dissipation of the device and using the thermal resistance value for a given package type, the maximum allowable ambient temperature for an application can be found using Equation 3. Overdrive Recovery BANDWIDTH - MHz The overdrive, or overload, recovery time of an amplifier is the time required for the output voltage to return to a rated output voltage from a saturated condition. This recovery time can be important in applications where the amplifier must recover quickly after a large transient event. The circuit in Figure 29 was used to evaluate the recovery time for the OPx50. Figures 30 and 31 show the overload recovery of the OP250 from the positive and negative rails. It takes approximately 0.5 ms for the amplifier to recover from output overload. The OPx50 family of amplifiers is well suited to driving capacitive loads. The device will remain stable at unity gain even under heavy capacitive load conditions. However, a capacitive load does not come without a penalty in bandwidth. Figure 32 shows a graph of the OPx50 unity-gain bandwidth under various capacitive loads. 1.0 VS = 2.5V RL = 10k TA = +25 C 0.8 0.6 0.4 OP250 VIN 1VP-P 10k 1k 9k VOUT 0.2 0 Figure 29. Overload Recovery Time Test Circuit 0 1 10 100 CAPACITIVE LOAD - nF 1k Figure 32. Unity-Gain Bandwidth vs. Capacitive Load As with any amplifier, an increase in capacitive load will also result in an increase in overshoot and ringing. To improve the output response, a series R-C network, known as a snubber, can REV. 0 -11- OP250/OP450 be connected from the output to ground in parallel with the capacitive load as shown in Figure 33. The proper snubber network on the output can significantly reduce output overshoot, although it will not increase the bandwidth. Table I shows some snubber network values for a given capacitive load. In practice, these values are best determined empirically based on the exact capacitive load for the application. +5V For more information on methods to drive a capacitive load with an op amp, please refer to the Ask the Applications Engineer article in Analog Dialogue, Vol. 31, Number 2, 1997. Single Supply Differential Line Driver OP250 VIN 100mV p-p RS 5 CS 1F VOUT Figure 36 shows a single supply differential line driver circuit that can drive a 600 load with less than 0.1% distortion. The design uses an OP450 to mimic the performance of a fully balanced transformer based solution. However, this design occupies much less board space while maintaining low distortion and can operate down to dc. Like the transformer based design, either output can be shorted to ground for unbalanced line driver applications without changing the circuit gain of 1. R3 10k 2 R5 50 R6 10k C3 47 F VO1 CL 47nF Figure 33. Schematic for Using a Snubber Network Table I. Snubber Network for Large Capacitive Loads R2 10k 3 A2 1 R7 10k +5V +12V 6 Load Capacitance (CL) 1 nF 10 nF 100 nF Snubber Network (RS, CS) 60 , 30 nF 20 , 1 F 3 , 10 F C1 22 F VIN 2 3 +5V A1 1 7 A1 R8 100k C2 1F 5 R9 100k RL 600 R1 10k A1, A2 = 1/2 OP250 GAIN = R3 R2 R10 10k R11 10k 6 5 Figure 34 shows the output of an OP250 in a unity gain configuration with a 1 nF capacitive load. Figure 35 shows the improvement in the output response with the snubber network added. VIN = 100mVp-p @ 100kHz CL = 1nF RL = 10k R12 10k R14 50 C4 47F VO2 A2 7 R13 10k SET: R7, R10, R11 = R2 SET: R6, R12, R13 = R3 Figure 36. A Low Noise, Single Supply Differential Line Driver R8 and R9 set up the common mode output voltage equal to half of the supply voltage. C1 is used to couple the input signal and can be omitted if the input's dc voltage is equal to half of the supply voltage. The circuit can also be configured to provide additional gain if desired. The gain of the circuit is: 50mV 2s AV = VOUT R3 = VIN R2 (5) Figure 34. Output of OP250 without Snubber Network CL = 1nF RL = 10k VIN = 100mVp-p @ 100kHz Where: VOUT = VO1 - VO2, R2 = R7 = R10 = R11 and, R3 = R6 = R12 = R13 Multimedia Headphone Amplifier Because of its large output drive, the OP250 makes an excellent headphone amplifier, as illustrated in Figure 37. Its low supply operation and rail-to-rail inputs and outputs can maximize output signal swing on a single +5 V supply. In Figure 37, the amplifier inputs are biased halfway between the supply voltages, which in this application is 2.5 V. A 10 F capacitor prevents power supply noise from contaminating the audio signal. 50mV 2s Figure 35. Output of OP250 with Snubber Network -12- REV. 0 OP250/OP450 +V + 5V 50k Direct Access Arrangement for Modems +V + 5V 10 F 1 F/0.1 F 50k LEFT INPUT 10 F 100k 1/2 OP250 20 270 F LEFT HEADPHONE 50k +V 50k 50k RIGHT INPUT 10 F 100k 10 F 1/2 OP250 20 270 F RIGHT HEADPHONE 50k Figure 39 illustrates a +5 V transmit/receive telephone line interface for 600 systems. It allows full duplex transmission of signals on a transformer coupled 600 line in a differential manner. Amplifier A1 provides gain which can be adjusted to meet the modem output drive requirements. Both A1 and A2 are configured so as to apply the largest possible signal on a single supply to the transformer. Because of the OP450's high output current drive and low dropout voltages, the largest signal available on a single +5 V supply is approximately 4.5 V p-p into a 600 transmission system. Amplifier A3 is configured as a difference amplifier for two reasons: (1) It prevents the transmit signal from interfering with the receive signal and (2) it extracts the receive signal from the transmission line for amplification by A4. Amplifier A4's gain can be adjusted in the same manner as A1's to meet the modem's input signal requirements. Standard resistor values permit the use of SIP (Single In-line Package) format resistor arrays. Couple this with the OP450 14-lead TSSOP or SOIC footprint and this circuit offers a compact, cost-effective solution. P1 TX GAIN ADJUST TO TELEPHONE LINE 1:1 ZO 600 6.2V 6.2V T1 R6 10k Figure 37. A Single-Supply Stereo Headphone Driver 1 VSY = 2.5V AV = +1 VIN = 300mV rms R3 360 R2 9.09k 2 A1 3 R1 10k C1 0.1 F TRANSMIT TXA 2k 1 R5 10k 0.1 THD + N - % +5V DC 6 7 A2 5 10 F R9 10k 2 R10 10k R13 10k R14 14.3k 6 R12 10k 5 A4 R7 10k R8 10k RL = 500 RL = 2k MIDCOM 671-8005 0.01 RL 10k P2 RX GAIN ADJUST 0.001 R11 10k 20 100 1k FREQUENCY - Hz 10k 20k 3 A3 1 RECEIVE RXA 2k 7 C2 0.1 F Figure 38. THD vs. Frequency A1, A2, A3, A4 = 1/4 OP450 The audio signal is coupled into each input through a 10 F capacitor. This large value insures the resulting high pass filter cutoff is below 20 Hz, preserving full audio fidelity. If the input already has the proper dc bias, then the coupling capacitor and biasing resistors are not required. A 270 F capacitor is used at the output to couple the amplifier to the headphone speaker. This value is much larger than the input capacitor because of the low impedance of the headphones, which can range from 32 to 600 or more. An additional 20 resistor is used in series with the output capacitor to protect the op amp's output in the event the output accidentally becomes shorted to ground. Headphone Driver Figure 39. A Single-Supply Direct Access Arrangement for Modems REV. 0 -13- OP250/OP450 * OP250 SPICE Macro-Model Typical Values * 10/97, Ver. 1 * TAM / ADSC * * Node assignments * noninverting input * | inverting input * | | positive supply * | | | negative supply * | | | | output * | | | | | * | | | | | .SUBCKT OP250 1 2 99 50 45 * * INPUT STAGE * M1 4 3 6 6 MNIN L=2u W=66u M2 5 2 6 6 MNIN L=2u W=66u M3 7 3 9 9 MPIN L=2u W=66u M4 8 2 9 9 MPIN L=2u W=66u RD1 99 4 5E3 RD2 99 5 5E3 RD3 7 50 5E3 RD4 8 50 5E3 VCM1 10 50 -.3 VCM2 99 11 -.3 D1 10 6 DX D2 9 11 DX EOS 3 1 POLY(3) (61,98) (73,98) (81,0) 3E-3 +1 1 1 IOS 1 2 .25E-12 IBIAS1 6 50 700E-6 IBIAS2 99 9 700E-6 * * CMRR=60 dB, ZERO AT 20kHz * ECM1 60 98 POLY(2) (1,98) (2,98) 0 .5 .5 RCM1 60 61 159.2E3 RCM2 61 98 159 CCM1 60 61 50E-12 * * PSRR=90dB, ZERO AT 200Hz * RPS1 70 0 1E6 RPS2 71 0 1E6 CPS1 99 70 1E-5 CPS2 50 71 1E-5 EPSY 98 72 POLY(2) (70,0) (0,71) 0 1 1 RPS3 72 73 1.59E6 CPS3 72 73 500E-12 RPS4 73 98 50 * * INTERNAL VOLTAGE REFERENCE * RSY1 99 91 100E3 RSY2 50 90 100E3 VSN1 91 90 DC 0 EREF 98 0 (90,0) 1 GSY 99 50 POLY(1) (99,50) -1.81E-3 1.5E-5 * * VOLTAGE NOISE REFERENCE OF 30nV/rt(Hz) * VN1 80 0 0 RN1 80 0 16.45E-3 HN 81 0 VN1 30 RN2 81 0 1 * * POLE AT 1.25MHz * G2 98 20 POLY(2) (4,5) (7,8) 0 5E-5 5E-5 R2 20 98 10E3 C2 20 98 12.7E-12 * * GAIN STAGE * G1 98 30 (20,98) 3.5E-4 R1 30 98 6.25E6 CF 30 45 135E-12 D4 31 99 DX D5 50 32 DX V1 31 30 0.7 V2 30 32 0.7 * * OUTPUT STAGE * M5 45 41 99 99 MPOUT L=2u W=6660u M6 45 42 50 50 MNOUT L=2u W=6660u EO1 99 41 POLY(1) (98,30) .9232 1 EO2 42 50 POLY(1) (30,98) .8914 1 * * MODELS * .MODEL MNIN NMOS(LEVEL=2,VTO=0.75, +KP=20E-6,CGSO=0,KF=2.5E-31,AF=1) .MODEL MPIN PMOS(LEVEL=2,VTO=-0.75, +KP=20E-6,CGSO=0,KF=2.5E-31,AF=1) .MODEL MNOUT NMOS(LEVEL=2,VTO=0.75, +KP=30E-6,LAMBDA=0.04,CGSO=0) .MODEL MPOUT PMOS(LEVEL=2,VTO=-0.75, +KP=20E-6,LAMBDA=0.04,CGSO=0) .MODEL DX D(IS=1E-16) .ENDS OP250 -14- REV. 0 OP250/OP450 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 8-Lead SOIC (SO-8) 0.1968 (5.00) 0.1890 (4.80) 8 1 5 4 8-Lead TSSOP (RU-8) 0.122 (3.10) 0.114 (2.90) 0.177 (4.50) 0.169 (4.30) PIN 1 0.0098 (0.25) 0.0040 (0.10) 0.0688 (1.75) 0.0532 (1.35) 0.0196 (0.50) x 45 0.0099 (0.25) 1 4 PIN 1 0.0500 0.0192 (0.49) SEATING (1.27) PLANE BSC 0.0138 (0.35) 0.0098 (0.25) 0.0075 (0.19) 8 0 0.0500 (1.27) 0.0160 (0.41) 0.006 (0.15) 0.002 (0.05) 0.0256 (0.65) BSC 0.0433 (1.10) MAX 0.0118 (0.30) 0.0075 (0.19) 0.0079 (0.20) 0.0035 (0.090) 0.256 (6.50) 0.246 (6.25) 0.1574 (4.00) 0.1497 (3.80) 0.2440 (6.20) 0.2284 (5.80) 8 5 SEATING PLANE 8 0 0.028 (0.70) 0.020 (0.50) 14-Lead Plastic DIP (N-14) 0.795 (20.19) 0.725 (18.42) 14 1 8 7 14-Lead TSSOP (RU-14) 0.201 (5.10) 0.193 (4.90) 0.280 (7.11) 0.240 (6.10) 0.060 (1.52) 0.015 (0.38) 0.130 (3.30) MIN 14 8 0.177 (4.50) 0.169 (4.30) PIN 1 0.210 (5.33) MAX 0.160 (4.06) 0.115 (2.93) 0.022 (0.558) 0.014 (0.356) 1 7 0.100 0.070 (1.77) (2.54) 0.045 (1.15) BSC SEATING PLANE 0.015 (0.381) 0.008 (0.204) PIN 1 0.006 (0.15) 0.002 (0.05) 0.0433 (1.10) MAX 0.0256 (0.65) BSC 0.0118 (0.30) 0.0075 (0.19) 0.0079 (0.20) 0.0035 (0.090) 0.256 (6.50) 0.246 (6.25) 0.325 (8.25) 0.300 (7.62) 0.195 (4.95) 0.115 (2.93) SEATING PLANE 8 0 0.028 (0.70) 0.020 (0.50) REV. 0 -15- -16- C3236-8-10/97 PRINTED IN U.S.A. |
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