Features

● Low power current: 1 μA

● gain bandwidth: 70kHz

● Uniform gain stability

● Low input bias current: 10Pa (maximum)

● Wide power supply range: 1.8V to 5.5V

● Input range: 200mv beyond track

] ● Output drive current: 8mA

● Open loop gain: 90db

● Micro packaging: SC70, SOT33-5, SOT33-8

] ● battery pack and power supply

● Portable telephone, paging machine and camera

● Solar system

● Smoke, gas and fire detection system

● Remote Sensor

● PCMCIA card

● Drive modulus converter

● Micro -power filter

OPA349 and OPA2349 are Ultra -low power consumption amplifier, provides 70kHz bandwidth, static current is only 1 μA. These rail -to -orbit input and output amplifiers are designed for battery power. The input co -mode voltage range extends 200mV outside the power rail, and the output voltage is swinging in the rail 350mv range, and the dynamic range is wide. Unlike some micro -power computing amplifiers, these parts are stable in unit gain and do not require external compensation to achieve broad band width. OPA349 is characterized by low input bias currents, allowing large source resistance and feedback resistance to use.

OPA349 can work at a power supply from 1.8V to 5.5V, and the performance has almost no change. Even in the case of low battery, it can ensure continuous excellent performance.

OPA349 has micro SOT23-5, SC70, and SO-8 surface installation and packaging. OPA2349 Dual has SOT23-8 and SO-8 surface installations. These small packages are very suitable for high -density applications, such as PCMCIA cards, battery packs and portable instruments.

The prescribed temperature of OPA349 is 0 ° C to+70 ° C. The prescribed temperature of OPA2349 is -40 ° C to+70 ° C.

OPAX349 related products

pin configuration

Typical features

TA u003d+25 ° C, vs u003d+5V, RL u003d 1M time, connect to VS/2, unless there is another explanation.

Application information OPA349 series operational amplifier is the unit gain stable stability You can work on a single power supply to make it highly universal and easy to use. 0.01 μF ceramic capacitors should be used to bypass the power. The OPA349 series operational amplifier conducted a comprehensive test in the+1.8V to+5.5V range. The typical characteristic curve shows parameters significantly changing with the working voltage or temperature. The ultra -low static current of OPA349 requires cautious application circuit technology to achieve low overall current consumption. Figure 1 shows the bias of the AC coupling amplifier. The resistance value must be large to minimize the current. Large feedback resistance values u200bu200band input capacitors and strange capacitors reactions have generated poles in the feedback network. A feedback capacitor may be required to ensure stability and limit over -punch or gain peak. Check the performance of the circuit carefully to ensure that the partial pressure and feedback technology meet the signal and static current requirements.

Rail -to -rail input

The input co -mode voltage range of the OPA349 series exceeds the power rail 200mv. This is achieved through a complementary input level. A N channel input difference is parallel parallel with a P channel differential (as shown in Figure 2). The N channel is effective for the input voltage near the track, usually above the positive power supply (V+) -1.3V to 200MV, and the input from 200mv to about (V+)-1.3V from the negative power supply below the negative electrode power supply is open. Essence There is a small transition area, usually (V+) -1.5V to (V+) -1.1V, two of which are opened. This 400 millivolo transition area can change 300 millivolves with the process. Therefore, at the low-end, the range of the transition zone (both stages) is (V+) -1.8V to (V+)-1.4V, and high-end (V+) -1.2V to (V+)-0.8V. In the 400MV transition zone, PSRR, CMRR, offset voltage, offset drift and THD may be reduced compared with the operation outside the area. For more information about the design of the rail input computing amplifier, see Figure 3, the design optimization of the rail input computing amplifier.

The optimized design of the rail input computing amplifier

In most applications, the operation is only within the range of one differential pair. However, some applications can cause the amplifier to be affected by the co -mode signal during the conversion process. Below in this case, the inherent loss of the two differential pairs may lead to the degeneration of the co -model suppression ratio and THD. The configuration of the unit gain buffer is the biggest problem.The wide input width, it will pass through the transition area. A design scheme is to configure the computing amplifier to the unit gain anti -phase device as shown below, and keep the non -interconnected input under the setting of the co -mode voltage outside the transition area. This can be implemented by the siger on the power supply. The design of the sterilizer should make the bias point of non -switching input outside the transition area.

Common model suppression

The CMRR of OPA349 specifies in two ways, so the best matching of a given application can be used. First of all, a co-mode suppression ratio of devices within the co-modular range of the transition zone (VCM LT; (V+) -1.5V) was given. When the application needs to use a differential input pair, this specification is the best indicator of the equipment performance. Secondly, the CMRR when VS u003d 5V is available throughout the common modular range.

Output drive to V-shaped rail

If the output voltage is driven to a negative (as shown in Figure 4A), the load connected to a single power supply ground (or V-power pins) may be possible. It will cause OPA349 or OPA2349 oscillation. Similarly, when the output voltage is close to V, the load that flows out of the output pins may also cause oscillation. After the output is driven by a positive drive, the operational amplifier will return to normal work after a few micro seconds.

Some operational amplifiers applications will cause this situation even if they are not connected to V-. The integralor in Figure 4B shows an example of this effect. Suppose the output is negative slope and saturate near 0V. Any negative jump at VIN will generate a positive output current pulse through R1 and C1. This may stimulate oscillation. The diode D1 prevents the input step from jumping out of the output at the orbit to pull the output current, thereby preventing oscillation.