MSP430 with 3 comparators

Haiqi Bian

Other Parts Discussed in Thread: MSP430F67791, LMV393

I want to find the MSP430-16 bits Ultra-low-power MCU with 3 comparators. I found out that MSP430F67791 have 3 comparators in the product list, but I can't find in its datasheet/ user's guide. Could you help me to verify if MSP430F67791 has 3 on-chip comparators? If not, could you give me the solution to find out MSP430 with 3 on-chip comparators. Thank you!

over 12 years ago

0 Jens-Michael Gross over 12 years ago

Guru 227245 points

This MSP doesn't have any comparators. It has multiple SD converters and an ADC10 (which can act as a comparator by its window detection mode)
It has four timers with up to three capture/compare units, but that's a completely different thing.

0 Haiqi Bian over 12 years ago in reply to Jens-Michael Gross

Prodigy 220 points

But here, what does "Comparators 3" mean?

0 Ilmars over 12 years ago

Guru 46710 points

Haiqi Bian said:
If not, could you give me the solution to find out MSP430 with 3 on-chip comparators.

Here will be solution:

http://www.ti.com/lsds/ti/microcontroller/16-bit_msp430/products.page#p1817=3;8

Honestly I am afraid that there's no such msp430 you are looking for. Those numbers are just comparator inputs specified. I would choose msp430 having DAC and use external comparator IC:

http://www.ti.com/lsds/ti/amplifiers-linear/comparator-products.page

0 Jens-Michael Gross over 12 years ago in reply to Haiqi Bian

Guru 227245 points

Well, that's a bit strange.

Checking the pin table of this MSP, I find CB0 to CB3 inputs and one CBOUT. So it has one comparator with four selectable inputs, even though not mentioned in the features list at the beginning of the datasheet.

So the table you took the picture from is apparently not correct.

0 Haiqi Bian over 12 years ago in reply to Jens-Michael Gross

Prodigy 220 points

I get this picture from here:

http://www.ti.com/product/msp430f67791

That's why I don't understand.

0 Haiqi Bian over 12 years ago in reply to Ilmars

Prodigy 220 points

The problem is I can't find out 3 or more comparators in the datasheet/user guide. Thank you~

0 Jens-Michael Gross over 12 years ago in reply to Haiqi Bian

Guru 227245 points

Haiqi Bian said:
The problem is I can't find out 3 or more comparators in the datasheet/user guide.

As far as I can tell, no MSP has more than one comparator module, even though there are MSPs with up to 8 input channels. Yet only one comparison can be done at a time. If you need more, you need to switch the channels by software.
It works if you need the comparator for monitoring one line, and form time to time you need it for comparing something else, before switching back to the monitoring mode. But you cannot use it for monitoring more than one signal simultaneously, to get an interrupt when one of them fails.

The 67xx can be used for two simultaneous monitoring actions, using the comparator for one and the ADC10_A for the other in window comparator mode. That's it.

0 Leo Bosch over 12 years ago in reply to Jens-Michael Gross

Guru 23000 points

Devices with 3x Op-Amp (also Comparator): MSP430FG43x & MSP430FG461x.

0 Haiqi Bian over 12 years ago in reply to Jens-Michael Gross

Prodigy 220 points

Sorry, I'm bit confused by the simultaneous monitoring action. What I'm going to do is to deal with one signal of voltage with some pulses (partial discharge) and set two references of voltage to count the positive pulse and negative pulse. Is this the simultaneous monitoring action?

0 Ilmars over 12 years ago in reply to Haiqi Bian

Guru 46710 points

Haiqi Bian said:
Is this the simultaneous monitoring action?

If pulse timing and/or polarity is unpredictable - then yes. I will be repeating here - you can use external comparators together with pin IRQ function. Such way you don't need complex msp430 having lot of unneeded pins and memory just to have built-in (comparator) function you are looking for. Pick LMV393 for example.

0 Haiqi Bian over 12 years ago in reply to Ilmars

Prodigy 220 points

Thank you so much!

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MSP430 with 3 comparators