Recommendations for commonly chosen ICs

[jbb]

Hi all

I'm finally getting a design underway and have selected some of the major components.  However, there are a few peripheral parts which I need to select. Can anyone suggest common / jellybean choices for the following:

• An I2C port expander.  I expect to have 2 of them on the same bus, so I'd like one with address select pin(s)
• A Digital to Analog Converter for DC level setting.  I need something like 4 channels @ 12 bits, and all the options on DigiKey seem to be really expensive at the moment. I2C preferred, SPI would be OK.
• A clock multiplier to get from a crystal (say 10 MHz) to 180 MHz.  I'm thinking the Si5351A...

Background: I want to build an Impedance Analyser to operate from 50 Hz to 10 MHz (and maybe above 10MHz in the future).

Current plan is to build an auto-balancing RF bridge.  Drive voltage (Force +) and balance current (Force -) sine waves will be generated by two channels of an AD9106 quad Direct Digital Synthesis (DDS) chip and appropriate analog circuitry.

The remaining two channels of the AD9106 generate a quadrature LO which is then used to demodulate the measurement signals back down to I and Q signals with a Tayloe mixer (aka a Zero IF approach).

Unfortunately, the AD9106 uses a common DDS frequency for all four channels.  The standard functionality lets you vary the phase shift and/or amplitude of each channel, but not generate a second frequency. Hence the initial plan above.  (I am toying with a notion that it might be possible to manipulate the AD9106 into generating an output which is offset from the main frequency, but I'm not super confident it's possible.)

I admired the Teensy-LCR by WeTec, which tops out around 90 kHz.  Moving up to 10 MHz should give me some visibility into the self resonant frequencies of home made transformers etc.

[Smokey]

careful out there!
https://www.eevblog.com/forum/dodgy-technology/mcp23017-same-part-number-two-fewer-inputs/

[PCB.Wiz]

An I2C port expander.  I expect to have 2 of them on the same bus, so I'd like one with address select pin(s)

The xx8574 is old but widely popular. Check if it is 'good enough'


A Digital to Analog Converter for DC level setting.  I need something like 4 channels @ 12 bits, and all the options on DigiKey seem to be really expensive at the moment. I2C preferred, SPI would be OK.

MCU's like EFM8BB3 / EFM8LB1 have 4 x 12b DACs and can be cheaper than DACs alone. How fast to they need to be ?


A clock multiplier to get from a crystal (say 10 MHz) to 180 MHz.  I'm thinking the Si5351A...
That was briefly hard to get, but seems better now.
There is also a clone MS5351M available on lcsc, which also keeps the Si5351A price honest.

[jbb]

DACs are basically DC, used for level setting. Even a 1 kSample/second update rate is likely sufficient