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LMV7235: High-speed low-noise PWM comparator circuit

Tak
Intellectual 480 points
Part Number: LMV7235
Other Parts Discussed in Thread: TLV3201, TLV3501, LMV7239

I am trying to develop a class D amplifier.
At this time, the LM319 was to be used for the PWM generator. Because of its high reputation for high speed and low noise.

However, I would like to use a slightly smaller comparator if possible. However, since the specifications indicating the audio performance of the comparator are not specified, it is not known whether a low noise circuit can be used.
I want to know if there is no problem using the LMV7235 for the PWM circuit for audio. Also, if there is a high-speed and low-noise comparator with another part number, please introduce it.

  • 0
    TI__Expert 4555 points

    Do you know the supply voltage that you plan on supplying your comparator with? By low noise are you referring to jitter specs or offset voltage?

    LM319 and LMV7235 are both open drain parts. You could use a faster push pull device such as the TLV3201 or TLV3501 - however the supply range on these devices are more limited. Because they are push pull, it will reduce the size of the solution since a pullup resistor is not needed.

    Regards,

    Jonny

  • 0 in reply to Jonathan Nguyen
    Intellectual 480 points

    Thank you for your reply.
    The power supply voltage can be determined flexibly, but we are considering whether to use + 5V.
    The noises I mean are offset, jitter and flicker(1/f) noise.

    I think that the transistor type is more advantageous than the CMOS type.  What do you think?
    From such a viewpoint, I think that the LM319 has been adopted in many sites.
    However, if possible, I would like to use a small comparator this time.
    Devices are always up to date.

    B.R. Tak

  • 0 in reply to Tak
    TI__Expert 4555 points

    I can't say I am as experienced as you with Class D amplifiers, but I think that a push pull comparator as your pwm should be ok. With an open drain/collector part like the LM319, much of the speed will be dominated by the RC constant from your pullup resistor.

    Can you share the input voltage range of your audio signal?

    Jonny

  • 0 in reply to Jonathan Nguyen
    Intellectual 480 points

    The voltage is OK at 5V.
    Because the circuit can be changed flexibly.
    I was just worried because the LM319 is often used for low noise PWM generation circuits.
    I was bothered by the fact that comparators aren't very specific about noise like operational amplifiers. (1 / f, jitter, offset, EIN etc)
    Perhaps there is no problem I care about.
    I implement LMV7239 and proceed with development.