I'm using a apd5100 pressure sensor to monitor arterial line blood pressure. Since its an integrated sensor, i figured i could directly connect it to a 16 bit ADC.However I ain't sure of the choice of ADC for this application...as 1. the sampling rate 2. architecture-SAR/delta sigma 3. Input configuration range
Kindly help me out.
Unfortunately, we do not have details on this device. Do you have the datasheet, company/product page link, or any other details on this sensor? If so, then we will gladly look into some suggestions for an ADC.
i apologise for the error...its an ADP5100 pressure sensor from panasonic...i decided to go for this one coz I couldnt fing any analog/digital output pressure sensors with a range of -700 to +700mmHg....if you have other suggestions, pls let know....Also, kindly answer my query with regards to the ADC.
Looks like the ADP5x00 will get you +/-100kPA. That should give you about .45 to 4.5V output. Depending on your sample rate and resolution requirements, there are plenty of data converters from Texas Instruments to choose from.
A one channel low power option might be to take the OPA365 configured as a simple voltage follower between the sensor and an ADS8326. The output of the amp goes to the (+) ADC input, the (-) adc input goes to ground and you have a simple low power single supply option with 16-bits of resolution. There are other options in the ADS8326 family that might be more appropriate based on what your end goals are - the ADS8326 datasheet lists six or seven ADC options on the first page if memory serves me.
Let us know how you make out, this sounds like a fun project!
Thanks a tonne :)
the datasheet of the ADS8326 states that Fclock=24*Fsample...why so? isnt clock frequency=no. of bits*sampling freq ? How many equivalent DCLOCKS would that be considering my Fsample=250kHz
ultimately my ADC output should go to a Spartan 3AN FPGA...
The maximum SCLK speed the ADS8326 device can tolerate is 6MHz. For 250KSPS, you would normally have the /CS tied low for 22 DCLKs to transfer data and high for two additional DCLK cycles between conversions - see the top of page 8 for details.
any way i can obtain the spice model of those ICs..
The product folder for OPA365 contains the SPICE model for it, which you can find via the following link:
As for the ADS8326, there are no available SPICE models for it. However, there are 2 EVMs available, if you'd like to use those with your pressure sensor. For the EVM alone, that you could wire into your FPGA, we have the ADS8326EVM. If you would like a "ready to go" setup, that includes a controller and software, we have the ADS8326EVM-PDK.
Before trying this circuit with the sensor, i want to build the circuit by simulating the output signal characteristics of ADP5100 sensor...how do i do so and give it to OPA365?
You may try simulating the input using TINA-TI.
any specific reason as to why u suggested this ADC? and is a voltage follower circuit necessary?
Also, if I'm simulating the output signal of the sensor, can I do so by connecting a 5k pot across 5V and gnd and give its output directly to any ADC which then communicates with an MSP430.
No specific reason for the ADS8326 other than its 'ease of use'. Typically a SAR adc wants to see a low impedance input. You may be able to get decent results with the 5K pot depending on your sample rate. In another post to this forum, you are looking for an 8-bit device in a DIP package. Here are a few:
thanks :) do i need to give an anti aliasing filter?
You always need some kind of band-limiting filter before a data converter. Sampling a signal always results in some kind of aliasing, you just need to be sure to keep the aliased signals below the noise floor of the converter. Besides, it's good practice to only use the bandwidth you really need to keep noise low, so limiting the bandwidth of the input signal is the right thing to do.
If you're sampling at 250kSPS, and your pressure signal is a fairly low frequency, then a simple RC filter may be all you need, or you can use FilterPro to design a second-order active filter at whatever your maximum signal frequency might be (100Hz, 500Hz?).
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.