XTR117: Pressure Sensor 4-20mA transmitter and amplifier circuit for Space Applications

Ammar Shkoukani said:

operating temperature range of -65C to 140F

correction

*operating temperature range of -65C to 140C

 Hi Ammar,

Ammar Shkoukani said:

for this two-wire 4-20mA transmitter with robustness for Space Applications 

Do these parts and application have radiation harden requirements? Or the application is for avionics electronics. Please clarify. 

Best,

Raymond 

Hi Raymond,

Ideally, the components would be radiation hardened. We are targeting a number of applications of which some do have radiation hardening requirements.

Prefer to use a general design across these applications though, but two separate designs is also a possibility(One with radiation hardening requirements, one without)

Thanks,

Ammar  

Hi Ammar,

Since the operating temperature range of -65C to 140C very wide, it is difficult to select a part with radiation harden + high operating range in combined specification. 

I think that you may have to go with discrete design approach for the 4-20mA current loop transmitter application. For instance, OPA2333-HT is one of HT part, but it only certified to -55C. My guess is that the OPA2333-HT may be able to handle -65C, but the performance may have to be verified.  Several other -HT op amps are OPA211-HT, OPA2211-HT, but the selection is limited. 

BTW -65C operating temperature may be met readily, but -65C soaking temperature and is able to power up after soaking at -65C is the question. Since -65C operating temperature is not specified generally, you have to perform the soaking tests on your own. -55C is typically military and space low end operating temperature ratings. 

Below is our military and space grade op amp selection.  

https://www.ti.com/amplifier-circuit/op-amps/precision/products.html#1498=HiRel%20Enhanced%20Product%3BHigh%20Temp&

We do not have the integrated solution in the current loop transmitter. You have to design the application with discrete solution. 

Please let me know how we are able to assist you. I may be able to send you a simulation once you are able to select an op amp for the application. 

Best,

Raymond 

Hi Raymond, 

For now lets assume the absolute minimum is -55C. 

Here are some high level design specs and requirements to consider, although nothing at the moment has been finalized

• 9-36V loop supply voltage
• 5-20mV/V output signal from sensor
• 4-20mA output signal
• Operating temperature range -55C to +125C
• Radiation hardening

I came across this TI document which seems relevant for the transmitter portion of the design. 

/cfs-file/__key/communityserver-discussions-components-files/14/snoaa73.pdf

Additionally, found another document that is relevant to the instrumentational amplifier portion of the design.

/cfs-file/__key/communityserver-discussions-components-files/14/snoaa71.pdf

Are there any application notes or components that you are aware of that would serve a similar function to the PGA309 for signal conditioning?

Hi Ammar,

This is tough one. Many of our product specified operating temperature between -55C to +125, but the guaranteed performance specification is typically between -40C to +125C. PGA309 is one of the example. Outside of the temperature performance specification will not be guaranteed by TI.  

If the specification also includes radiation hardened requirements, the selection will be decreased significantly (if any). In our AFE product lines, we have some HART communication protocol, but it is still limited by the temperature operating range.  

https://www.ti.com/lit/ds/symlink/afe88101.pdf?ts=1718228185792&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FAFE88101%253Futm_source%253Dgoogle%2526utm_medium%253Dcpc%2526utm_campaign%253Dasc-dc-null-44700045496400844_prodfolderdynamic-cpc-pf-google-wwe_int%2526utm_content%253Dprodfolddynamic%2526ds_k%253DDYNAMIC+SEARCH+ADS%2526DCM%253Dyes%2526gad_source%253D1%2526gclid%253DCjwKCAjwjqWzBhAqEiwAQmtgT8Tss6Qieka8esuhIOZBe1Tiig2FfHoDBzpSI1idskU31nZhHRDRWhoCMP0QAvD_BwE%2526gclsrc%253Daw.ds

https://www.ti.com/lit/ab/slaae91/slaae91.pdf?ts=1718228381043&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FAFE88101%253Futm_source%253Dgoogle%2526utm_medium%253Dcpc%2526utm_campaign%253Dasc-dc-null-44700045496400844_prodfolderdynamic-cpc-pf-google-wwe_int%2526utm_content%253Dprodfolddynamic%2526ds_k%253DDYNAMIC+SEARCH+ADS%2526DCM%253Dyes%2526gad_source%253D1%2526gclid%253DCjwKCAjwjqWzBhAqEiwAQmtgT8Tss6Qieka8esuhIOZBe1Tiig2FfHoDBzpSI1idskU31nZhHRDRWhoCMP0QAvD_BwE%2526gclsrc%253Daw.ds

https://www.ti.com/lit/an/slaaeh0/slaaeh0.pdf?ts=1718164428911

https://www.tij.co.jp/lit/ug/tidueg0/tidueg0.pdf?ts=1718229002742&ref_url=https%253A%252F%252Fwww.google.com%252F

If your company is able to integrate PGA309 or similar current loop transmitter in a special space approved package, then this may be better design approach to take. The discrete current loop solution will work, but they will be expensive vs. the integrated solution. 

If you have other questions, please let us know. 

Best,

Raymond