Features

● Rail -to -track input and output

● High output current: 660 mAh

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Single power supply: +5 V to +12 v

● Broadband: 5 MHz

●

High conversion rate: 3V/MS

●

Low distortion: 0.01%

● The unit gain stable

● No phase reversal

● Short -circuit protection

● Drive capacitance load: 10 nf

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● Multimedia

● Telecom

● DAA transformer driver

● LCD driver

● Low -voltage servo control

● modem

●

field Effect transistor drive Generally explains

OP179 and OP279 are rail pairs, high output current, single power amplifier. They are designed for low -voltage applications for current or capacitor load driving capabilities. OP179/OP279 can be absorbed and the source current is ± 60 mAh (typical value), and it is stable when the capacitor load is 10 mAh. The applications benefited from the high output current from OP179/OP279 include driving headphones, monitors, transformers and power transistors. The combination of strong output with the unique input level can maintain extremely low distortion and wider co -mode range even in the design of single power supply.

OP179/OP279 can be used as buffer to provide greater driving capabilities that are usually provided than CMOS output. CMOS ASIC and DAC usually have outputs, which can swing to positive power and ground, but cannot drive more than a few millis.

The bandwidth is usually 5MHz, and the conversion rate is 3V/μs, which makes these amplifiers very suitable for single -power applications that require audio bandwidth when used in high -gain configuration. The voltage is as low as 4.5V and up to 12V, which can guarantee operation.

When using OP179/OP279 in a +5 volt system, you can get very good audio performance. THD is lower than 0 under the load of 600 .01%, noise is 21 nv/√Hz. The power current of each amplifier is less than 3.5 mAh.

Single OP179 is provided in the 5-line SOT-23-5 package. Specify within the temperature range of industrial (-40 ° C to+85 ° C).

OP279 has 8-core plastic impregnation, TSSOP and SO-8 surface installation and packaging. They are specified within the temperature range of industry (–40 ° C to+85 ° C).

pin configuration

Order guide

Typical performance chart

Operation Theory

OP179/OP279 is the latest product of the single power equipment series of simulated device extensions , Designed for multimedia and telecommunications markets. It is a high output current driver, rail -to -rail input/output computing amplifier, which is powered by a single+5V power supply. It is also suitable for other low -power voltage applications that require low distortion and high output current. In order to combine the high output current and low -distortion characteristics of the rail input/output operation, new circuit design technology is adopted.

For example, Figure 1 illustrates the simplified equivalent circuit of OP179/OP279 input level. It consists of two parallel PNP differentials to Q5-Q6 and Q7-Q8 with diode protection networks. The diode network D5-D6 and D7-D8 are used to cut the applied differential input voltage to OP179/OP279 to protect the input transistor from damage to the avalanche. The basic difference between the two PNP gains is that the Q7-Q8 is usually closed, and their input is input buffer by the Q1-D1-D2 and Q9-D3-D4 from the computing amplifier. It is best to understand the function that applies the co-mode voltage: when the input of OP179/OP279 is input in the middle of the power supply, the difference in the differential signal path gain is controlled by the resistance load (via R7, R8) Q5-Q6. When the input conjunctive level is reduced to the negative power supply (VNEG or GND), the input transistor current source i1 and i3 are forced to be saturated, thereby forcing Q1-D1-D2 and Q9-D3-D4 networks; however, Q5-Q6 remains maintained Activation status and provide input level gain. On the other hand, when the community input voltage increases to the direction of the positive power supply, the Q5-Q6 is driven to the deadline, the Q3 is driven to saturated, and the Q4 becomes active, providing bias for the Q7-Q8 differential pair. Q7-Q8 Differential point is about (VPO-1 V).

The key problem here is the behavior of input bias current at this stage. OP179/OP279 in the common mode voltage range (VNEG+1V) The input bias current within the range of (VPOS – 1 V) is arithmetic in the Q1Q5 and Q9-Q6 in the Q1Q5 and Q9-Q6. Outside of this range, the input bias current is mainly based on the Q5-Q6 (input signal close to VNEG) and Q1-Q5 (Q9-Q6). Due to this design method, the input bias current of OP179/OP279 not only shows different amplitude, but also shows different polarity. This input bias current is the best explanation in Figure 3. Therefore, it is important that the effective source impedance balance connected to the OP179/OP279 input terminal to obtain the best DC and communication performance. In order to achieve rail-to-orbit output characteristics, the design of OP179/OP279 adopts a complementary aggregate emission pole (or GMRL) output (Q15-Q16), as shown in Figure 23. These amplifiers provide the output current until they are forced to enter the saturation state, and the saturation state occurs at about 50 millivoltors at any power rail. Therefore, their saturated voltage is the limit of the maximum output voltage swing among OP179/OP279. Due to the use of public emission pole amplifiers, the output level also shows voltage gain; and, the voltage gain at the output stage (therefore, the opening gain of the device) shows the strong dependence of the total load resistance with OP179/OP279 output, as shown in the figure as shown in the figure 7 shown.

Enter overvoltage protection

Like any semiconductor device, as long as there is a condition for input to exceed any power voltage, you must consider the input over -voltage of the device's input of the device characteristic. When a voltage occurs, the amplifier may be damaged, depending on the size of the external voltage and the size of the fault current. Figure 24 shows the input overvoltage characteristics of OP179/OP279. The diagram is generated from the curve tracker from the ground power and connected to the input terminal. It can be seen that when the input voltage exceeds any of the power supply exceeds 0.6 volts, the internal PN is connected to the power, and the allowable current allows the current from the input flow to the power supply. If the simplified equivalent input circuit (Figure 22) shown, the OP179/OP279 does not have any internal flow resistance, so the fault current can rise rapidly to the destructive level.

As long as the input current is limited to 5 mAh or less, the input current does not cause inherent damage to the device. For OP179/OP279, once the input voltage exceeds 0.6 V, the input current will quickly exceed 5 mA. If this situation continues, an external series resistor should be added. The size of the resistance is calculated with a maximum overvoltage. For example, if the input voltage can reach 100 V, the external resistance should be (100 V/5 mA) u003d 20 k . If it is exposed to overvoltage, the resistance should be connected in series with one or two inputs. Similarly, in order to ensure the best DC and AC performance, it is important to balance the level of power impedance. The general excessive voltage characteristics of the amplifierFor more information, please refer to the application guide for the 1993 seminar, which can be obtained from the Simulation Equipment Literature Center.

The output phase reversed

Some operational amplifiers designed for the work of a single power supply. When the input is driven by the effective common modulus range, it will The output voltage phase reverses. For a single power supply dual -type computing amplifier, the negative power source determines the lower limit of the scope of the co -mode. Using these devices, external clamping diode, anode grounding, cathode input, input signal offset is prevented from exceeding the negative power of the device (ie, GND) to prevent the occurrence of phase changes in the output voltage. JFET input amplifiers may also have phase reversal. If so, a series of input resistance is usually required to prevent it.

As long as the input voltage does not exceed the power supply voltage, OP179/OP279 is not limited by a reasonable input voltage range. Although the output of the device does not change the phase, the large current can flow through the input protection diode, as shown in Figure 22. Therefore, when the input voltage may exceed the power supply voltage, the technique recommended in the input overvoltage protection part should be adopted.

Capacitor load driver

OP179/OP279 has excellent capacitor load driving capabilities. It can directly drive up to 10nf performance charts, which are shown in the titles of small signal overwhelming and load capacitors (Figure 18). However, even if the device is stable, the capacitance load will not have no bandwidth loss. As shown in Figure 25, the bandwidth is reduced to less than 1MHz for loads greater than 3NF. The ""buffer"" network at the output will not increase the bandwidth, but it can indeed significantly reduce the over -adjustment of a given capacitance load. The buffer consists of a series R-C network (RS, CS), as shown in Figure 26, connecting from the output end of the device to the ground. The network work with the load capacitor CL parallel to provide phase lag compensation. The actual value of resistance and capacitors is best determined based on experience.

The first step is to determine the value RS of the resistor. The good start value is 100 (usually, the best value will be less than 100 ). This value is reduced until the small signal transient response is optimized. Next, determine that CS-10μF is a good starting point. This value is reduced to the minimum value of acceptable performance (usually 1 μF). For the situation of 10 NF load capacitors on OP179/OP279, the best buffer network is 20 series 1 μF. The advantages of the oscilloscope in Figure 27 are obvious. The top record is collected under the 10NF load, and the bottom record is collected at 20 and 1 μF buffer network position. The number of salvage and bells is greatly reduced. Table 1 shows the buffer network example of some large load capacitors.

Overload recovery time

The overload or driving recovery time of the operation amplifier is the time required for the output voltage from the saturation state to its linear area. This recovery time is important in applications that the amplifier must recover after a large transient event. The circuit in FIG. 28 is used to evaluate the overload recovery time of OP179/OP279. OP179/OP279 recovers about 1 μs from positive saturation, and recovered from negative saturation by about 1.2 μs.

Output transient current recovery

In many applications, the operational amplifier is used to provide medium -level output current to drive ADC, small motor, transmission cable Input with current source. It is in these applications that the computing amplifier must quickly return to the level of the load current, while maintaining a stable load current level. Due to its high output current capacity and low -loop output impedance, OP179/OP279 is the best choice for such applications. For example, when it generates or reduces 25 mAh stable load current, the level of 10 mAh (that is, 25 mAh to 35 mAh and 35 mAh to 25 mAh) of the load current changes, OP179/OP279 shows less than less than 500 mAh to 0.1%recovery time.

Precision negative voltage reference

In many data collection applications, a precise negative reference is needed. Generally speaking, any positive voltage benchmark can be converted to negative reference voltage by using the calculation amplifier and a pair of matching resistors in the inverter configuration. The disadvantage of this method is that the largest single error source in the circuit is the relative matching of the resistor used.

The circuit shown in FIG. 29 avoids the need for tight matching resistors by using a source of points circuit. In this circuit, the output of the benchmark voltage provides the input drive to the integrator. In order to maintain the balance of the circuit, the integralor adjusts its output to establish an appropriate relationship between the reference voltage VOUT and GND. Therefore, you can simply choose a variety of negative output voltage by replacing appropriate reference ICs. In order to speed up the stability of the circuit, R2 can be reduced to 50K or smaller. Although the time constant of the integralizer selected here is 1ms, there is still room for weighing circuit bandwidth and noise by increasing R3 and reducing C2. Just simply add a PNP transistor and a 10 k the resistor can maintain the shutdown function in the circuit. One thing to pay attention to using this method is that although the rail -to -rail transition amplifier works best in the application, when any load current needs to be provided, these operational amplifiers need a limited net air (MV). This problem should be taken into account the choice of negative circuit power supply.

High -output current, buffer benchmark/regulator

Many applications require stable electricityFor pressure output, its potential is relatively close to the unexplained input source. This ""low -voltage difference"" benchmark/regulator is easily implemented with the rail ring -rail output computing amplifier, and it is particularly useful when using high -current devices such as OP179/OP279. A typical example is 3.3 V or 4.5 V reference voltage generated from the 5 V system power supply. It requires a three -terminal benchmark for these voltages, such as Ref196 (3.3V) or Ref194 (4.5V). Both of them have low -power characteristics, and the source output is 30 u0026#9251; ma or smaller. Figure 30 shows how such a benchmark can be equipped with an OP179/OP279 buffer to obtain higher current and/or voltage levels, as well as Sink and Source load capacity.

The low -voltage difference performance of the circuit is provided by U2 level. U2 level is half of the OP179/OP279 connected to the basic reference voltage generated by U1. The low voltage saturation characteristics of OP179/OP279 allows the load current up to 30 mAh in the figure as a 5 volts with high DC accuracy to 3.3 volt converters. In fact, the measurement value of the DC output voltage of the incremental DC output voltage of the 30 mAh load current is less than 1 millivol. This corresponds to equivalent output impedance less than 0.03 . In this application, the stable 3.3V from U1 is applied to U2 through the noise filter R1-C1. U2 copy U1 voltage within a few cubes, but there is a higher current output at VOUT1, and the ability to absorb and source output current-is different from most IC references. The R2 and C2 in the U2 feedback pathway provides bias compensation for the minimum DC error and additional noise filter.

The reference/regulator's transient performance of the reference/regulator is also quite good, which is mainly determined by the R5-C5 output network. As shown in the figure, for any polarity, the transient state is about 10 MV peaks, and it is stabilized within 8 μs within 2 MV. Although there is a space for optimizing transient response, any changes in the R5-C5 network should be verified by experimental verification to avoid the possibility of excessive ringing of certain capacitors.

In order to adjust VOUT2 to another (higher) output level, an optional resistor R3 (dotted line display) is added to turn the new VOUT1 into:

]

For example, for VOUT1 u003d 4.5 V and Vout2 u003d 2.5 V of Ref192, the gain required for U2 is 1.8 times, so the ratio of R2 and R3 is 0.8: 1 or 18 k : 22.5 k u0026#8486 ;. Note that for the lowest VOUT1 DC error, the parallel combination of R2 and R3 should remain equal to R1 (as shown in here), and the R2-R3 resistor should be a stable metal membrane type with close tolerance.

This circuit can use 5 V to 3.3 V reference/regulator as shown in the figure, or it can also be used with on/off. As mentioned earlier, the output is opened/closed by using logic to control the pin 3 of U1 with logic control signal. Note that when using the open/off control, the resistor R4 should be used with U1 to accelerate the speed of the switch.

The direct access device of the phone line interface

FIG. 31 shows the only +5 V transmission/receiving phone line interface of 110 transmission system. It allows the transformer to be transmitted in a full dual -time transmission in a differential manner on the transformer coupling. The amplifier A1 provides a adjustable gain to meet the driving requirements of the modem output. A1 and A2 are configured to apply the maximum possible signal on the single power of the transformer. Due to the high output current driver and low voltage difference voltage of OP179/OP279, the maximum signal available on a single +5 V power supply is about 4.5 V p-P, and enter 110 transmission system. The amplifier A3 is configured to the differential amplifier, which is used to extract the receiving signal from the transmission line to enlarge through A4. The gain of A4 can be adjusted in the same way as A1 to meet the input signal requirements of the modem. The standard resistance value allows the resistance array in the SIP (single -line package) format. Combining it with OP179/OP279 8 -line SOIC packaging, the circuit provides a compact and cost -sensitive solution.

Single power supply, remote strain signal regulator

The circuit in FIG 8486; Method in the regulating circuit of the strain meter. In this circuit, OP179/OP279 has two functions: (1) Output across R1 through the +2.5 V of the servo REF43, providing 20 mA drivers for 350 In this way, the tiny changes of the strain will generate a large differential output voltage at the input end of the AMP04. (2) For the dynamic range of the maximum circuit, the other half of the OP179/OP279 is configured to be configured to be a power distributor connected to the REF terminal connected to AMP04. Therefore, the tension or compression in the application can be measured through the circuit.

AMP04 configuration to gain 100, generating the circuit sensitivity of 80 mv/ The capacitor C2 is used for AMP04's pin 8 and 6 to provide a 16hez noise filter. If you need additional noise filtering, you can use optional capacitors CX at the input terminal of AMP04 to provide differential noise suppression.

Single power supply balance line drive

The circuit in FIG. 33 is the unique line drive circuit used in professional audio applicationsPu, and have been modified to automobile audio applications. On a single +12 V power supply, the line drive shows less than 0.02%in the entire audio frequency band (not displayed). For loads greater than 600 increased distortion performance to positions with less than 0.002%. This design is a transformer -free, and the output co -modular noise suppression of the output of the transmission system is crucial. Like a transformer -based system, without changing the circuit gain 1, any output can be used for a short circuit to the unbalanced circuit driver application. Other circuit gains can be set according to the formulas in the figure. This allows the design to be easily configured as non -reversing, reversal or differential operations.

Single -power headset amplifier

Due to its high -speed and large output drives, OP179/OP279 is an excellent headset drive, as shown in Figure 34. Its low power operation and rail pairing input and output provide the maximum signal swing on a single+5 V power supply. In order to ensure the maximum signal of the driving headset, the bias of the amplifier input to V+/2 is 2.5 V. The average power of the positive power supply is 100 k the resistance is divided into two 50 k its public point is bypassed by 10 μF to prevent the power noise pollution audio signal.

Then the audio signal coupled to 10 μF capacitors per input end through AC. It needs a large value to ensure that the audio information of 20 Hertz is not blocked. If the input already has appropriate DC bias, there is no need to communicate coupling and bias resistance. The output terminal uses 220 μF capacitors to couple with the amplifier and the headset. Because the low impedance of the headset (range is 32 to 600 ), the value is far greater than the value used for input. Another 16 the resistor is used in series with the output capacitor, and the output level of the operator is protected by restricting the capacitor discharge current. When the driver 48 load, the circuit is displayed at a low output drive level (not displayed) less than 0.02%THD+N. The large current output level of OP179/OP279 can drive this heavy load to 4V P-P and maintain THD+N, which is less than 1%.

Active filter

OP179/OP279 has several source filter topology.

There are two popular structures, common SALLENKEY (SK) voltage control voltage sources (VCVS) and multiple feedback (MFB) topology. These filter types can be used for Qualcomm (HP), low -pass (LP), and Tongtong (BP) filters. The SK filter uses the op amp as a unit or a higher -gain fixed gain voltage follower, while the MFB structure uses it as a inverter. The simplification of these filters is discussed here.The system builds blocks.

Uniform gain, Sallen-Key (VCVS) filter

Qualcomm configuration

Figure 35A is the unit gain of the OP179/OP279 part of the HP form of the HP format of the pole SK filter 2 pole SK filter. Essence For this filter and its LP correspondence, the gain in the band is inherently unified, and the signal phase is irreversible due to the follower connection. For simple and practical, the capacitor C1-C2 is set to equal, and the resistance R2-R1 is adjusted to the ratio ""n"