General description

Low voltage operation and low power consumption lmc6574 /2 is an ideal choice for battery power supply system. The performance of the 3V amplifier is guaranteed by 2.7V to ensure that it can work normally during the life of the battery. These Gualan three -links also enable the analog circuit to work on the 3.3V power supply for digital logic under the same conditions. Because each amplifier is dissipated, the battery life is only the power of microva. LMC6574/2 does not sacrifice the function of low pressure operation. LMC6574/2 generates 120 decibel opening gains and traditional amplifiers, but LMC6574/2 can implement this function through 2.7V power supply. The design features of these amplifiers are low -pressure operation. The output voltage swings to maximize the signal -to -noise ratio and dynamic signal range between the orbit. The range input voltage range of the co -mode input from 800 millivol to 100 millivolves below the positive power supply. This device uses the advanced dwellery of the silicon grid CMOS in China. LMC6572 can also be encapsulated in MSOP, and its size is almost half of the SO-8 device.

Features

(Unless otherwise explained, it is typical)

Guarantee 2.7V and 3V performance

Rail output vessel (power rail 5 5 Within MV, 100 k load)

Ultra -low power current: 40 μA/amplifier

Low cost

Ultra -low input current: 20Fa

] High -voltage gain@vs 2.7V, RL 100 K : 120 db

Specify for 100 k and 5 k load

in the MSOP software package Provided

Application

sensor amplifier

Portable or remote device

battery operation instrument

Data collection system

] Medical Device

improved

TLV2322

and TLV2324 alternative

Absolute maximum rated value (Note 1)

ESD tolerance (Note 2) 2000V

Differential input voltage ± power voltage

Input/output pins voltage (V+)+0.3 volts, (V ) 0.3 volts [123 il ]

Power voltage (V+ V ) 12 volts

The current at the input pin ± 5 ma

The current at the output pin (Note 3 ) ± 10 ma

Power pins current 35 mAh

DiversionTemperature (welding, 10 seconds) 260 ; C

Storage temperature range 65 ; C to+150 ; #730; C

Working rated value (Note 1)

Power supply voltage 2.7V ≤V+≤11v

Concluding temperature range

lmc6572ai, LMC6572BI # 8722; 40 ; C≤TJ≤+85 ; C

lmc6574ai, LMC6574BI 40 ; C ≤TJ≤+85 ; (Θja)

N packaging, 8 -pin mold pressure DIP 115 ; c/w

M packaging, 8 -pin surface installation 193 ; C/w

MSOP Component, 8 -pin mini SO 217 ; C/W

n packaging, 14 -pin mold pressure DIP 81 ; C/W

M packaging, 14 -pin surface installation 126 ; C/W

2.7V DC special characteristics

Unless there are other regulations, all the limits of TJ 25 ; C are guaranteed. V+ 2.7V, v 0V, VCM VO V+/2 and RL GT; 1M Bold facial restrictions are suitable for extreme temperature.

2.7V DC electricity characteristics (continued)

Unless there are other regulations, all the limits of TJ 25 ; C are guaranteed. V+ 2.7V, v 0V, VCM VO V+/2 and RL GT; 1M Bold facial restrictions are suitable for extreme temperature.

2.7V AC electrical characteristics

Unless there are other regulations, TJ 25 ; C, V+ 2.7V, V 0V , VCM VO V All guarantees+/2 and RL GT; 1 m . Bold facial restrictions are suitable for extreme temperature.

2.7V AC electrical characteristics (continued)

Unless there are other regulations, TJ 25 ; C, V+ 2.7V, V #872222 ; 0v, all guarantees of vcm vo v+/2 and r gt; 1 m . Bold facial restrictions applicable toExtreme temperature.

Note 1: Absolute maximum rated value indicates the limit value that may be damaged by the device. The work rated value indicates that the device is in a normal working state, but the specific performance cannot be guaranteed. Please refer to the electrical characteristics about the specifications and test conditions of the guarantee.

Note 2: Human model, 1.5 k series 100 PF.

Note 3: Applicable to single power and sub -supply operations. Continuous short -circuit operations at higher environmental temperatures can lead to more than maximum allowed temperature 150 ; C.

Note 4: The maximum power consumption is the functions of TJ (MAX), θJa, and TA. The maximum allowable power consumption at any ambient temperature is pd (TJ (maximum) ta)/θJa. All numbers are suitable for packaging directly welded to the PC board.

Note 5: Typical values represent the most likely parameter specifications.

Note 6: All limits are guaranteed by testing or statistical analysis.

Note 7: V+ 3V, VCM 1.5V, RL connected 1.5V. Source pole test, 1.5V ≤VO ≤ 2.5V. Sinking test, 0.5V ≤VO ≤ 1.5V.

Note 8: connected as a voltage follower, and the order input is 1.0V. The specified number is the slower in the positive and negative conversion rate.

Note 9: Reference Input, V+ 3V, RL 100K , connected to 1.5V. Each Ampen is motivated by 1kHz sequence, generating VO 2VPP

Typical performance characteristics vs +3V, TA 25 ; C, unless otherwise specified

Typical performance characteristics vs +3V, TA 25 ; 25 ; C, unless there are other regulations (continued)

Typical performance characteristics vs +3V, TA 25 ; Continuous)

Application prompt

1.0 low -voltage amplifier topology

LMC6574/2 adopts a novel computing amplifier design topology structure structure , Make it able to keep the rail -to -rail output swing evenly when driving a large load. Instead of relying on push -pull unit gain output buffer level, the output level is directly obtained from the internal integrator, these two low output impedance great gains. Special feedback compensation design technology is used to maintain the stability under more extensive operating conditions than traditional micro -power computing amplifiers. These functions make LMC6574/2 easy to design and provide higher on this superIn the case of low power, it is faster than the product.

2.0 Input Capacity Compensation

For a amplifier with ultra -low input current, the use of large value feedback resistors is very common, such as LMC6574/2. Although LMC6574/2 is highly stable in a wide range under working conditions, a large feedback resistance will react even if the input -end capacitor value is small and the amplifier is calculated to reduce the phase of the phase. The capacitance of the computing amplifier input comes from the sensor, photoelectric diode and circuit board parasitic. The impact of input capacitors can be surrounded by a capacitor, CF feedback resistance (Figure 1):

Because it is usually difficult to know the accuracy of CIN, CF can adjust through experimental adjustment through experimental adjustment , To obtain the required pulse response. Refer to LMC60 and LMC662 to learn more about the input capacity compensation. When high input impedance is needed, it is recommended to use LMC6574/2. Protecting the input cable not only reduces leakage, but also reduces the input capacitance of the bruises. (High impedance seeing the layout of the printing circuit board)

3.0 tolerance load tolerance

Direct capacitor load will reduce many operational amplifiers. The polar dots in the feedback circuit are combined by the output impedance and capacitance load of the computing amplifier. This polar point causes the cross frequency of the phase lags at the unit gain, leading to an oscillating or underwriting pulse impact. With some external components, the operational amplifier can easily indirectly drive the load, as shown in Figure 2.

In the circuit in FIG. 2, R1 and C1 are used to offset the loss of phase habits of high -frequency components

Application prompts (continued)

The input terminal of the output signal returns to the inverter input terminal of the amplifier, so as to maintain the phase margin circulation throughout the feedback.

4.0 Printing circuit board layout

High impedance work is generally believed that any circuit leakage current that must be operated is less than 1000Pa, which requires a special PC plate layout. When a person wants to use the ultra -low bias current of LMC6574/2 than 20 Football Association, it is important to have a good layout. Of course, it is quite simple to obtain low leaks. First of all, users cannot ignore the surface leakage PC board, even if they sometimes look acceptable, because under the conditions of high humidity or dust or pollution, the surface will leak obviously. In order to minimize the surface leakage, the foil that is surrounded by the LMC6574/2 input is the terminals of the capacitor, diode, conductor, resistance, relay, etc. connected to the input end of the computing amplifier input, as shown in Figure 3. In order to produce significant results, the protective ring should be placed at the top and bottom of the PC board. This computer foil must be connected to the same voltage voltage as the input of the amplifier because there is no leakage current that can flow between two points at the same potential. For example, PC board tracking to padsThe resistance is 1012 and is generally considered to be very large. If the trajectory is a 5V bus, close to the input board. This will cause the performance of LMC6574/2 to decrease by 250 times the actual performance. However, if the input voltage is 5 mv, the resistance of 1011 even 1011 The typical connection of the standard computing amplifier protection ring is shown in Figure 4 Configuration

Designer should realize that the designer should realize A PC machine plate is arranged for several circuits is another technology that is better than the protective ring on the PC board: Do not insert the input pins of the amplifier into the board, but bend it in the air and use only the air as the insulating layer. Air is an excellent insulator. In this case, you can give up some advantages of the PC board structure, but these advantages are sometimes worth using point -to -point efforts in the air wiring. See Figure 5

Application prompt (continued)

5.0 spice macro model

can provide spice macro model for LMC6574/2. This model includes accurate simulation:

Enter the common model voltage range

frequency and transient response

GBW's dependence on load conditions

Static and dynamic dynamics Power current

Output swing depends on the load conditions

and more feature disks listed in the macro model.