Dear sir or madam
We are using the LM2901AV and the datasheets requires that the Common-mode input-voltage range stays below Vcc-2V.
My questions is: How do I calculate the Common-mode voltage?:
1. Ucm = (Uplus + Uminus) / 2; E.g. Ucm=(2V+5V)/2=3.5V
2. Or is it the lower voltage of the maximal voltages on one of the two inputs. E.g. Uplus.max=2V; Uminus.max=5V; Ucm=2V
If the device is suppiled with 5V, case 1 would violate the VICR stated in the datasheet, where case 2 would be fine.
Thanks for your answer
Regards Lars Hummel
Each input is considered separately. To be truly in the common mode range, both inputs must be less than VCC-2V.However, most comparators (including LM2901) only require that one input remains in common mode range for proper output. The LM2901 also allows for input voltage greater than VCC, if the other input is in the common mode range.
Therefore only one input needs to be in the common mode range at a time. Effectively case 2.
Regards,Ronald MichallickLinear Applications
TI assumes no liability for applications assistance or customer product design. Customer is fully responsible for all design decisions and engineering with regard to its products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning Customer's design. If Customer desires engineering services, the Customer should rely on its retained employees and consultants and/or procure engineering services from a licensed professional engineer (LPE).
Does the "most comparators (including LM2901) only require that one input remains in common mode range for proper output" comment apply to the TLV3011?
The TLV3011 is a rail to rail input comparator. The data sheet allows the inputs to be up to 200mV beyond the supply rails.There are diodes from the inputs to both supply rails so the inputs should not exceed the rails by 200mV at any time.
I guess I did not ask the right question. If one of the TLV3011 inputs (the inverting for example) is driven to a voltage high or low enough such that the diode to the associated supply rail conducts, will the output still be as expected? Or can the output phase reverse? Let's say there is a 10kOhm resistor to limit the current.
Start a new thread with TLV3011 in the subject. I do not have this information, but some else will.
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.