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LM311: New quad comparator device suggestion

Part Number: LM311


I will like to suggest a new quad comparator device (sorry if this isn’t the right place for this).

The LM311 comparator has been around for many years, but still seems very popular because of some unique features, like ±15V supplies allowing for high bipolar voltages to be compared on the input pins. This is very useful in all types of audio circuits, such as amplifiers and synthesizers using ±12V supplies, and in motor control circuits.
Also it is fast, and unlike other comparators has an isolated emitter brought out on pin 1. This will often be connected to ground allowing the open-collector output to be interfaced to a microcontroller interrupt input, for example using 0V/3.3V logic levels (while at the same time the comparator is supplied from much higher bipolar levels, like ±12V).

Many designs often need several comparators (e.g. a 16-voice synthesizer needs 16 comparators), but as the LM311 only comes in single packages cost and board space is increased.
I think it would be great to have a quad version in a 16-pin TSSOP package.

It would be fine for the four ‘isolated emitters’ to be joined and brought out to only one pin (as this will usually be connected to ground). And I don’t remember having encountered a design using the Balance/Strobe pins, so these could be omitted allowing for a quad comparator to fit in a 16-pin package.

  • Hi Peter,

    Thanks for reaching out and I appreciate your suggestion. We are actually developing an upgraded and dual channel version of this device which is expected to release sometime early next year. Would you be able to implement 2 dual devices in replacement of the quad for your design? We do not currently have quad channel options, but your feedback and suggestions do provide us some valuable insight. Thanks again for your use of the forum. 

  • Hi Chi,

    Thanks for helping. This new dual version sounds great. I will look out for it’s release next year.

    I guess there will also be a market for a quad version, since most applications either use only one comparator or several (4, 8, 16).
    Using a 16-pin package would allow for both an open-drain and push-pull output version (saving the need for the four pull-up resistors). The push-pull version would then have four supply pins, e.g. +12V and -12V bipolar supplies, and the logic-level supplies (e.g. 3.3V and ground).
    Or even better, if technically possible, a device that can either be configured as push-pull or open-drain (determined by if the positive logic-supply pin is connected to a voltage or not).

    Best regards,

  • Hi Peter,

    Thanks again for your insight.  I cannot say too much as it is a public forum, but I think this dual variant may be what you are looking for in terms of what you just mentioned Slight smile