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Small and cheap MCU with DAC
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Wimberleytech:

--- Quote from: nick_d on December 22, 2018, 12:26:04 am ---So Daddy :)

Is it true that the cheaper family members omit the DAC, this seems to be so based on the different posts here but I did not do a thorough survey.

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At the time, it was all about die size...getting the cost down.  Same with the ADC.  Had to go with an 8-bit to save area.

--- Quote ---Also, why choose 8051, the memory model seems a bit unfriendly to my modern C-oriented eye but perhaps there are good reasons for this? Or is it due to commercial reasons such as compatibility, licensing, availability of an in-house 1T 8051 core?

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Good question.  You may not like the answer.  We knew of a good core at a good price so we bought it and ultimately bought the group that made the core.  Simple as that.


--- Quote ---Do you design the core or is it more of a matter of integrating IP blocks via a standard bus structure?

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Totally custom from the bottom up.

--- Quote ---Do you use a HDL, such as Verilog or VHDL? What about simulation, are gate level and transistor level sims done before masks are ordered? Do you use expensive proprietary layout and routing tools?

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Verilog.  Syopsys and Cadence tools.  A very refined methodology to ensure accuracy.  In the later days, we did top-level simulations only to ensure blocks were connected properly (pch bias current to nch mirror...stuff like that)

We were taping out a new core every four months with heavy reuse.  Virtually all of the products are still selling...18 years later.
Unixon:
BTW, why so many microcontrollers that have a built-in ADC consisting of a DAC and a comparator circuit don't offer a buffered output from this internal DAC?
Wimberleytech:

--- Quote from: Unixon on December 22, 2018, 02:31:20 pm ---BTW, why so many microcontrollers that have a built-in ADC consisting of a DAC and a comparator circuit don't offer a buffered output from this internal DAC?

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I would say that most DACs used in SAR ADCs are charge-scaling.  These do not work as static DACs.

The 12-bit ADC on the early Silabs MCUs is a combination voltage-scaling/charge-scaling DAC.  The voltage-scaling portion could be used as a stand-alone DAC.  The Silabs 8-bit DAC is totally charge-scaling (for all the early ones).
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