Analog.com Analog Dialogue Wiki English 简体中文 日本語
EngineerZone
EngineerZone
  • Log In
  • Site
  • Search
  • User
  • Forums

    Popular Forums

    • RF and Microwave
    • Power Management
    • Video
    • FPGA Reference Designs
    • Precision ADCs
    • Linux Software Drivers
    • SigmaDSP Processors & SigmaStudio Dev. Tool

    Product Forums

    • A2B
    • Amplifiers
    • Analog Microcontrollers
    • Clock and Timing
    • Data Converters
    • Direct Digital Synthesis (DDS)
    • Energy Monitoring and Metering
    • Interface and Isolation
    • MEMS Inertial Sensors
    • Processors and DSP
    • Switches/Multiplexers
    • Temperature Sensors
    • Voltage References
    View All

    Application Forums

    • Audio
    • Automated Test Equipment (ATE)
    • Condition-Based Monitoring
    • Depth, Perception & Ranging Technologies
    • Embedded Vision Sensing Library
    • Motor Control Hardware Platforms
    • Optical Sensing
    • Precision Technology Signal Chains Library
    • Video
    • Wireless Sensor Networks Reference Library

    Design Center Forums

    • ACE Evaluation Software
    • ADEF System Platforms
    • Design Tools and Calculators
    • FPGA Reference Designs
    • Linux Software Drivers
    • Microcontroller no-OS Drivers
    • Reference Designs
    • Signal Chain Power (SCP)
    • Software Interface Tools
    • System Demonstration Platform (SDP) Support
  • Learn

    Highlighted Webinar

    Maximize the Benefits of High Bandwidth Current Sense Amplifiers for Space Constrained Applications

    Recent Discussions

    • Pluto is not receiving data
    • ADALM-pluto sampling frequency
    • ADALM PLUTO SDR
    • Bad FIT image format and MSD mounting errors in firmware built for Sidekiq Z2
    • set the sample rate to 30MHz or the maximum that usb2.0 allows

    Places

    • ADI Education Home
    • ADI Webinars
    • StudentZone (Analog Dialogue)
    • Video Annex
    • Virtual Classroom

    Latest Webinars

    • Maximize the Benefits of High Bandwidth Current Sense Amplifiers for Space Constrained Applications
    • Design Efficient Power Solutions for Battery-powered Applications
    • Shunt-based Energy Metering in High-Power Applications
    • Isolating GigaSpeed: Unlocking Data Integrity for USB and HDMI Communication
    • Extend Battery Life and Maximize Performance - Let Supervisors Do The Work
    View All Webinars
  • Community Hub

    Challenge Yourself!

      KCC's Quizzes AQQ244 about Wafer Processing Yield puzzle
    View All

    Places

    • Community Help
    • Logic Lounge
    • The Weekly Brew

    Resources

    • EZ Code of Conduct
    • Getting Started Guide
    • ADI: Words Matter
    • Community Help Videos
    View All
  • Blogs

    Highlighted Blogs

    Join the Analog Devices IEEE Radar Challenge

     

    Seeing is Believing but Smart Surveillance Cameras Let You Speak and Listen Too!

    Latest Blogs

    • We are Celebrating a Milestone on EngineerZone: Meet Our 100K Member!
    • How to Raise the Resolution of an Optical Motor Encoder without Changing the Disk
    • The Changing Nature of Logistics and Retail Automation
    • Variable Speed Drive 101
    • How to Optimize Voltage Regulators for Powering an Audio Amplifier
    Read All Blogs

    ADI Blogs

    • EZ Spotlight
    • The Engineering Mind
  • Partners

    Electronic Design Services - PartnerZone

    • Boston Engineering
    • Calian, Advanced Technologies
    • Colorado Engineering Inc. (DBA CAES AT&E)
    • Clockworks Signal Processing
    • Epiq Solutions
    • Fidus
    • PalmSens
    • Richardson RFPD
    • Tri-Star Design, Inc.
    • VadaTech
    • Vanteon
    • X-Microwave
    View All
Amplifiers
Amplifiers
Documents Current sense to digital output
  • Forums
  • Video/Images
  • Members
  • Tags
  • More
  • Cancel
  • +Documents
  • Tags List Amplifiers
  • +General Information: FAQ
  • +AD59: FAQ
  • +AD202: FAQ
  • +AD203: FAQ
  • +AD210: FAQ
  • +AD215:FAQ
  • +AD22100: FAQ
  • +AD22151: FAQ
  • +AD22151G: FAQ
  • +AD594: FAQ
  • +AD600: FAQ
  • +AD603: FAQ
  • +AD604: FAQ
  • +AD605: FAQ
  • +AD608: FAQ
  • +AD620: FAQ
  • +AD621: FAQ
  • +AD623: FAQ
  • +AD623BRZ: FAQ
  • +AD626: FAQ
  • +AD628: FAQ
  • +AD629: FAQ
  • +AD630: FAQ
  • +AD632: FAQ
  • +AD633: FAQ
  • +AD636: FAQ
  • +AD637: FAQ
  • +AD664: FAQ
  • +AD734: FAQ
  • +AD7357BCPZ: FAQ
  • +AD736: FAQ
  • +AD811: FAQ
  • +AD817: FAQ
  • +AD822: FAQ
  • +AD823: FAQ
  • +AD825: FAQ
  • +AD829: FAQ
  • +AD846: FAQ
  • +AD855: FAQ
  • +AD8002: FAQ
  • +AD8005: FAQ
  • +AD80066: FAQ
  • +AD8009: FAQ
  • +AD8012: FAQ
  • +AD8015: FAQ
  • +AD8016: FAQ
  • +AD8019: FAQ
  • +AD8033: FAQ
  • +AD8036: FAQ
  • +AD8039: FAQ
  • +AD8041: FAQ
  • +AD8041S: FAQ
  • +AD8042: FAQ
  • +AD8045: FAQ
  • +AD8061: FAQ
  • +AD8066: FAQ
  • +AD8074: FAQ
  • +AD8075: FAQ
  • +AD8079: FAQ
  • +AD8105: FAQ
  • +AD8108: FAQ
  • +AD8111: FAQ
  • +AD8112: FAQ
  • +AD8113: FAQ
  • +AD8114: FAQ
  • +AD8128: FAQ
  • +AD8129: FAQ
  • +AD8130: FAQ
  • +AD8131: FAQ
  • +AD8132: FAQ
  • +AD8134: FAQ
  • +AD8137: FAQ
  • +AD8138: FAQ
  • +AD8138S: FAQ
  • +AD8139: FAQ
  • +AD8145: FAQ
  • +AD8174: FAQ
  • +AD8185: FAQ
  • +AD8191: FAQ
  • +AD8195: FAQ
  • +AD8207: FAQ
  • +AD8208: FAQ
  • +AD8210: FAQ
  • +AD8211: FAQ
  • +AD8214: FAQ
  • +AD8217: FAQ
  • +AD8218: FAQ
  • +AD8220: FAQ
  • +AD8221: FAQ
  • +AD8225: FAQ
  • +AD8227: FAQ
  • +AD8230: FAQ
  • +AD8231: FAQ
  • +AD8232: FAQ
  • -AD8237: FAQ
    • AD8237 - Pitfalls to avoid
    • AD8237 - Recommendation for driving an ADC
    • AD8237 - How do I take full advantage of AD8237 performance?
    • AD8237 - Disadvantages of indirect current feedback
    • AD8237 - Application example
    • AD8237 - Difference from other ADI instrumentation amplifier
    • AD8237 - Advantages of indirect current feedback
    • controlling the BW pin on the AD8237
    • Current sense to digital output
  • +AD8253: FAQ
  • +AD8265: FAQ
  • +AD8283: FAQ
  • +AD8295: FAQ
  • +AD8302: FAQ
  • +AD8304: FAQ
  • +AD8305: FAQ
  • +AD8306: FAQ
  • +AD8307: FAQ
  • +AD8309: FAQ
  • +AD8310: FAQ
  • +AD8314: FAQ
  • +AD8318: FAQ
  • +AD8319: FAQ
  • +AD8321: FAQ
  • +AD8324: FAQ
  • +AD8328: FAQ
  • +AD8330: FAQ
  • +AD8331: FAQ
  • +AD8332: FAQ
  • +AD8333: FAQ
  • +AD8334: FAQ
  • +AD8336: FAQ
  • +AD8337: FAQ
  • +AD8338: FAQ
  • +AD8339: FAQ
  • +AD8397: FAQ
  • +AD8421: FAQ
  • +AD8422: FAQ
  • +AD8428: FAQ
  • +AD8476: FAQ
  • +AD8495: FAQ
  • +AD8500: FAQ
  • +AD8515: FAQ
  • +AD8519: FAQ
  • +AD8532: FAQ
  • +AD8538: FAQ
  • +AD8541: FAQ
  • +AD8551: FAQ
  • +AD8552: FAQ
  • +AD8555: FAQ
  • +AD8556: FAQ
  • +AD8557: FAQ
  • +AD8561: FAQ
  • +AD8564: FAQ
  • +AD8567: FAQ
  • +AD8592: FAQ
  • +AD8597: FAQ
  • +AD8602: FAQ
  • +AD8605: FAQ
  • +AD8606: FAQ
  • +AD8608: FAQ
  • +AD8610: FAQ
  • +AD8611: FAQ
  • +AD8622: FAQ
  • +AD8624ARUZ: FAQ
  • +AD8628: FAQ
  • +AD8629: FAQ
  • +AD8638: FAQ
  • +AD8643ACPZ: FAQ
  • +AD8646: FAQ
  • +AD8648: FAQ
  • +AD8655: FAQ
  • +AD8661: FAQ
  • +AD8662: FAQ
  • +AD8666: FAQ
  • +AD8674: FAQ
  • +AD8675: FAQ
  • +AD8677: FAQ
  • +AD8682: FAQ
  • +AD9101: FAQ
  • +AD9257: FAQ
  • +ADA4000-2: FAQ
  • +ADA4004: FAQ
  • +ADA4077-2: FAQ
  • +ADA4096: FAQ
  • +ADA4096-2: FAQ
  • +ADA4302-4: FAQ
  • +ADA4350: FAQ
  • +ADA4411: FAQ
  • +ADA4500-2: FAQ
  • +ADA4528: FAQ
  • +ADA4528-X: FAQ
  • +ADA4637-1: FAQ
  • +ADA4661-2: FAQ
  • +ADA4666-2: FAQ
  • +ADA4807: FAQ
  • +ADA4807-2: FAQ
  • +ADA4817: FAQ
  • +ADA4895: FAQ
  • +ADA4897: FAQ
  • +ADA4897-1: FAQ
  • +ADA4898-2: FAQ
  • +ADA4899-1: FAQ
  • +ADA4922-1: FAQ
  • +ADA4927: FAQ
  • +ADA4930: FAQ
  • +ADA4938-1: FAQ
  • +ADA4940-1:FAQ
  • +ADA4941-1: FAQ
  • +ADA4950-1: FAQ
  • +ADA4960-1: FAQ
  • +ADCMP341: FAQ
  • +ADCMP343: FAQ
  • +ADCMP552: FAQ
  • +ADCMP553BRM: FAQ
  • +ADCMP566: FAQ
  • +ADCMP572: FAQ
  • +ADCMP573: FAQ
  • +ADCMP580: FAQ
  • +ADCMP600: FAQ
  • +ADCMP602: FAQ
  • +ADCMP609: FAQ
  • +EVAL-FW-BPDF1: FAQ
  • +EVAL-PRAOPAMP: FAQ
  • +MAT01: FAQ
  • +MAT02: FAQ
  • +Mat12: FAQ
  • +MAT14: FAQ
  • +OP07: FAQ
  • +OP1177: FAQ
  • +OP16: FAQ
  • +OP184: FAQ
  • +OP2177: FAQ
  • +OP279: FAQ
  • +OP27AZ: FAQ
  • +OP281: FAQ
  • +OP284: FAQ
  • +OP285: FAQ
  • +OP290: FAQ
  • +OP293: FAQ
  • +OP295GS: FAQ
  • +OP297GSZ: FAQ
  • +OP37: FAQ
  • +OP400S: FAQ
  • +OP4177: FAQ
  • +OP484AM: FAQ
  • +OP484S: FAQ
  • +OP497: FAQ
  • +OP90: FAQ
  • +OP97: FAQ
  • +Opamps: FAQ
  • +OPx177: FAQ
  • +REF01: FAQ
  • +REF02: FAQ
  • +REF02A: FAQ
  • +REF193: FAQ
  • +REF195: FAQ
  • +REF198: FAQ
  • +REF43NBC: FAQ
  • +Right Leg Drive (RLD): FAQ
  • +SFP-RDK: FAQ
  • +SPICE: FAQ
  • +UG-084: FAQ
  • +VGAs: FAQ
  • +Precision Technology Learning Modules

Current sense to digital output

Q 

I have a high side current sense resistor of 2.5 milliohm, with 0..15A current.
I want to set up a system that will light an LED when the current is above
approx 200mA. I was thinking of using the AD8237 and the ADCMP341. My thinking
is the voltage at 200mA and above across the sense resistor will be 500uV and
greater. So the output from the AD8237 ( at G=1000) can be 0.5V which will
output a high on the ADCMP341 (as it is above the 400mV internal reference).
Below 200mA will result in a low condition. The LED current need only be a few
mA so the 5mA output current of the ADCMP341 should be enough. I have attached
a block schematic. The entire system needs only to work at approximately 10Hz.
The LED is a charging status indicator. The design is cost sensitive and there
is ample PCB area available. It is an all analogue system. There is no
microprocessor in the design. I would like an accuracy of 10% (+/-20mA). The
system power available is +5V and ground only. I will not be able to perform
any calibration of the system at the production stage to compensate for an
offset. If I am not on the correct path, can you suggest an alternative design
for
inside the green box as in the attached pdf?

 

A 

AD8237 is a good choice. You can take G=1000, set it to high bandwidth mode and
still get 1kHz bandwidth, which will help to settle quickly. Or I guess G=800
just to match the 400mV threshold as close as possible. 1% resistors would be
fine, the error budget will be dominated by the offset anyway. The ±75µV offset
voltage of the AD8237 translates to a ±15% error at 200mA. Increasing the sense
resistor would improve this, so there is an inherent accuracy vs power
tradeoff. I would also look at AD8293G160. It is used in many systems like this
and it has lower offset (50uV), but it has a fixed gain of 160, which is only
80mV at 200mA in. But if the shunt resistance is increased, maybe it is worth a
look.

Either way, I would come up with a circuit to clamp the output below 5V. For
AD8237, this could be as simple as 1 or 2 low-leakage diodes between OUT and FB
to bypass the gain resistor at high Vout. With the AD8237 in a gain of 800 and
15A in, the output will want to go to 30V. At 500% overdrive with a micropower
CMOS amplifier, it might take seconds to recover unless you prevent the
saturation in the first place. One more thing, you may want some input
protection resistors for the AD8237 because load or even trace inductance can
cause voltage spikes for any rapid change in current. The AD8237 has a very
high ESD rating (8kV HBM with no external components), but no long term
integrated overvoltage protection.

Also, maybe it’s just not shown in the diagram, but I would consider setting
some slight hysteresis for the comparator.

Attachments:
Diagram4ADI.pdf
  • ad8237
  • Share
  • History
  • More
  • Cancel
Related
Recommended
Social
Quick Links
  • About ADI
  • ADI Signals+
  • Analog Dialogue
  • Careers
  • Contact us
  • Investor Relations
  • News Room
  • Quality & Reliability
  • Sales & Distribution
  • Incubators
Languages
  • English
  • 简体中文
  • 日本語
myAnalog

Interested in the latest news and articles about ADI products, design tools, training and events?

Go to myAnalog
Analog Logo
©1995 - 2023 Analog Devices, Inc. All Rights Reserved
沪ICP备09046653号-1
  • Sitemap
  • Legal
  • Privacy & Security
  • Privacy Settings
  • Cookie Settings