Can I use OPA2322 in a single supply configuration? I plan to use 5V and 2.5V as virtual ground.
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OPA2322 Single Supply
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Choose between PGA204 and PGA281.
I'm design a fron-end of a data aquision system. I find there are two candidates from TI's page, PGA204 and PGA281. It seems PGA281 has higher performance. But it's cheaper than PGA204? What's the reason?
My design need a very large gain, so I want to cascade two PGAs, so may I use PGA281 + PGA204 ( PGA204 is used to convert the differential output of the PGA281 to single output)?
Or can I use PGA281 + PGA281, and only use one output of the second PGA281 as the input to the low-pass filter? Is this will derate the performance of PGA281?
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which is best suitable amplifier for 10Microvolt signal with inbuilt filter and d.c off set removal?
Hello
This is about a radiometer system that measures plasma electron temperature.since the signal strength is very small we require good amount of amplification and filtering is obvious to remove cosmic noise and line noise.
The output of the radiometer is a schottky detector (out:SMA (m) connector) that goes as the input of the electronics. it is basically a highly sensitive diode that senses RF power and gives the output in voltage form.so the input would be a few micovolts (say 10 microvolt to 100 mv).its video bandwidth would be around 1 MHz.
we require an electronics module that
1. would sense such low signal.
2.Amplify the signal for further processing...in steps ( 1-10,000)
3.With minimum intrinsic noise as possible.
4.Bandwidth of 10 KHz.
5.DC removal circuit.( The RF part contains amplifiers that produce some offset at the output only on energizing..this offset (voltage) needs to be zeroed first for the final AC type voltage coming from plasma)
for reference i have attached a file containing basic block building system....
please suggest best solution from TI.....
Thank you.....(Please visit the site to view this file)
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one problem about the output voltage of PGA309
hi ti.
I have used pga309 on my products,but i find one problem about PGA309 output voltage, i take sample the output voltage of PGA309 in my design,and display this voltage。but i find the voltage is not stable。 Voltage is change after a long time later。could you tell me how to solve this problem？？
thank you very much！！
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PGA280 with 64 CH MUX
I have 64 differential channels of analog data muxed, where each channel has a DC voltage ranging from 1mV to 16V to the PGA280. I need to cycle sequentially through these channels (e.g. channel 1 sample 1, channel 2 sample 2, etc) at a rate of 100ksamples/sec, with gains changing from the 1/8 setting to the 176 (128*1&3/8) settings depending on the voltage present. My question is the PGA280 Gain Bandwidth product high enough to cycle through these channels and produce an accurate result (lets say 0.1%)? I am not sure if I am interpreting figure 16 from the PGA280 datasheet the gain vs frequency correctly. I understand that for an AC signal the gains are no longer constant past about 20khz, however since my signals are slowly changing DC can that be ignored? or should I go by the switching frequency of the mux, therefore I could only switch up to 10khz and get accurate results?
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IVC102 inexplicable jump when S1 opened after integration
Using the IVC102 as recommended (data sheet page 7 Figure 3a), and with nothing on the IVC102's input (left floating within its guard ring), Testing is now being performed to characterize drift. This was an issue that we found on a previous board design and so for this one we improved guarding and took extra care to eliminate/reduce any leakage paths possible. No feedback resistor is used here. We want to eliminate any noise.
The test follows this sequence:
- open inverting input switch (S1)
- close reset switch (S2)
- wait 1 second
- open reset switch
- close input switch
- integrate for 30 seconds
- open input switch
- read value
- repeat
Before we start the integration and with the reset switch CLOSED, we see about +0.0005 V at the output.
With 100pf selected (default for my board) the drift amounts to -0.025V every 60 seconds. This seems reasonable, and when I change capacitance to 40pf, the rate is consistent, rising to -0.047V/60 seconds.
There are two values I don't understand just yet. Perhaps a TI Engineer can chime in here:
- Following integration, we OPEN the input switch (leaving the reset switch unchanged (open)), At this point, the output value suddenly changes from the expected -0.025V to -0.038 V. Why? The data sheet tells us that opening S1 will leave the integration value on the internal capacitors until we reset.
- Drift is greater when we perform our testing with S1 OPEN (not connected to the outside). We see -0.058V every 60 seconds when we integrate in this condition. I'd expect a higher drift rate with S1 CLOSED as outside influences come into play. My guess is that the outside influences are opposing the higher (internal?) drift rate.
A bit of information on how S1 and S2 are interfaced: I'm using a TI SN74LVC2G17 (dual Schmitt-Trigger buffer) between my microprocessor (MSP430FR5969) control lines for the two switches and the IVC102. This is a design change which assures signal purity and noise immunity for the switches.
Also, digital and analog gnd is joined at an interface connector on the preamplifier board and the switch lines are guarded by digital gnd, per the data sheet (just in case).
Here's a snippet:
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Question about LMP91000 Mechanical layout,
Hello,
I have been looking for the LMP91000 mechanical layout for the chip and i cant find it. i need it to make a library for a senior design. I am using Eagle for the PCB design but there is no library for the LMP.
does anyone have the mechanical layout?
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PGA309 with 350 ohm Load Cell
G'day
I am using the PGA309 design with 1k load cells without any problems.
My new design is to use 350 ohm load cells with Vref = 2.5 & Vexc = 2.075. This creates more than 5.9mA consumption on the bridge alone.
Based on the reference design (SLAU526), which is the best way to reduce this current for a 4-20mA output?
Thanks
Cheers
Dirk
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High Voltage Ground Fault Detection circuit
We are developing a product with a 380Vdc high resistance mid-point ground power distribution system. I need a cheap and simple ground fault detection circuit and attached below is what I have come up with so far. I need to isolate the high voltage DC from the control circuitry. A micro-controller will monitor the output of the ADS1013 ADC to detect a ground fault. If there are no shorts from the +/-190Vdc rails to chassis gnd, the output of the OPA244 will be 0V and the differential output of the AMC1200 will be 0V. If the -190V rail shorts to chassis gnd, the OPA244 will go to ~0.25V and the diff output will go to ~2V.
This doesn't have to be ultra precision, I just need a way to detect if one of the high voltage rails have shorted to chassis. I want the digital output so that I can set the "trip" point in software depending on how sensitive we need the detection to be. So the question is: are there better parts that I could use to accomplish this function?
Thanks
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LM331 scaling for under 100Hz operation
Hello -
I am trying to scale the LM331 to work with 0 - 50Hz and produce 0-9V output signal. This signal is then scaled with a voltage divider 0-3V for DSP.
I worked on the equations outlined in the datasheet, and seem to be not working. Is there a worksheet for this part that I can use to scale this part?
Also, how much the %ON time of the input frequency affect the output voltage and performance of this part?
Please let me know.
Best regards.
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TLV2402QDGK Quiescent Current
Hi,
I have tested the TLV2402QDGK (laser print TI19 QWX) and my measurments for the per channel Iq is around 10/11 uA. In the datasheet it says that it should be at 1uA. I measured this by just providing a 3.3V power supply to VCC and connected the GND pin to ground. Rest of the pins were left open.
Is there a mistake in my measurement set up, or why is my Iq higher than the specific value in the datasheet? I have tested this with several devices / channels.
Best regards,
Chris
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LMC6482
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XTR110 - Output Load Resistance
Hello everyone!
I want to buy this device XTR110 to build a Voltage to Current Converter.
I already have the Voltage range from 0V to 5V that will be used as Input. (in fact, I tried to convert this voltage in current by using a simple BJT NPN Transistor as a current source controlled by voltage, but it didn't work as expected).
In the Output, I'm using a PLC to receive and read the 4-20mA signal, but the idea of my project is use other receivers with Resistance from 100 until 500 Ohms, and the current should be stable.
The datasheet of XTR110 specifies a typical RL of 250 Ohms in output (Figure 1). My question is: if use a power supply about 20V and use a device in the output with load resistance until 500 Ohms, the output current will be the same?
Thank's!
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I have a doubt of a charge amplifier with a piezoelectric sensor
Hello all,
I have a question about the charge amplifier with a piezoelectric sensor as shown above.
The first image shows a piezoelectric sensor and its equivalent circuit and the second one shows the charge amplifier with the sensor.
Since piezoelectric sensors have a very high impedance, Rp, the amplifier should have a very high input impedance in a voltage mode. Otherwise, the amplifier should have a very low input impedance in a charge mode to feed all the charge from the sensor to the feedback capacitor.
However, if I put a resistor, Ri, as shown above, is it fine?
I think the input signal to the amplifier will be dropped due to the Ri, but a TI application note (SLOA033A) shows the circuit.
I wonder how the circuit works with a piezoelectric sensor having very high impedance.
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Load cell problem
Im using a LM 324 quad op amp to design an instrumentational amp. I would like a gain of 1000. For the Rgain value i am using 2000 ohm resistor and for the R value i am using 1M ohm resistor. When i connect the 5V power supply and the laod sensors i get an output of 2.6V constant, regardless of whether ipush down on the load cells or not.. I am wondering what I am doing wrong. The voltage output should change in correspondence with pushing down on the load cell?
I am using a SEN-10245 load cell.
The equation i am using for the gain is Av = (1 +2R/Rgain)
I am trying to build a digital scale.
I loaded the circuit diagrams i am following
Any help on the subject is appriciated.
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LMP2011/TL061 input-referred current noise
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Iset unit of LM4250
Dear Technical Support Team,
I have a question about LM4250.
Page 3 of this datasheet describes that Iset for absolute max is 150nA, but other pages such as Page 4 describe it's unit is μA.
Is it correct unit for absolute max of Iset?
Best Regards,
y.i
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INA125P PDIP package and INA125UA SOIC Package
We have tested the given circuit using INA125P DIP package. At the 16th pin , we got 10V with respect to ground , to power up the load cell. Also we have given the output of the loadcell to pins 6 and 7 of INA125P with a gain resistor of 220ohms and we received the output (at pin 10 ) correctly. But now we are using INA125UA SOIC package instead of the INA125P .With same circuit given below, INA125UA is giving only 0.22V at 16th pin instead of 10V. So we are not being able to power up the loadcell using INA125UA. Why we are not being able to get 10v at 16th pin of INA125UA using the same circuit. Kindly help us as soon as possible.
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LMP91000 COSH sensor (H2S + CO)
Can you confirm that a pair of LMP91000's can be used with a COSH sensor (H2S + CO)? I would assume that I can connect counter, reference, and one of the two workers of the COSH sensor to one LMP91000, then connect the 2nd worker to 2nd LMP91000 utilizing only the TIF section. I noticed that the TIF section can be used in support of a galvanic 2-terminal sensor, ignoring the A1 circuit, so I assume that I can take this approach in support of the COSH sensor. Please confirm.
Thanks,
Dave
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Connect Multiple XTR117 Devices
Hi Collin,
I would like to know if is possible to connect more than one XTR117 to build a multiple output device.
Thanks
Daniel
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