I was searching for an integrated low-current, high-voltage analog MUX, and I came across the MP4832A. My understanding is that this IC is serially-programmable, daisy-chainable with other MP4832A devices, and contains 32 SPST switching channels with bleed/pull-down resistors at their outputs. I was hoping to short all 32 outputs together in order to mimic a 32:1 MUX, but the resulting load of 32 bleed resistors in parallel would excessively load my signals. I was wondering if MPS had any alternative integrated solutions that I could use as a 32:1 analog MUX with minimal/no output loading.
Some bigger notable differences between the 32A and the 33A would be the smaller package size (7mm x 7mm BGA) and the difference in the voltage supplies required for operation (10V for the 33A as opposed to 12V for the 32A, 3.3V is still needed for both).
In the 32:1 analog MUX configuration, what would be the required load according to your application?
We would be using the MP4832A/MP4833A (or whatever more suitable IC there may be) for automated test equipment. Namely, we were hoping to automate the routing of various signals to an oscilloscope port (8 MΩ input impedance). The IC would ideally be a passthrough from the signal source to the oscilloscope, but if we had to tolerate additional loading (say from bleed resistors in parallel with the oscilloscope input impedance), it would have to be above ~1.2MΩ in order to keep the total impedance above 1MΩ.
I found a similar part (MP4816–not the MP4816A) that does not have any bleed resistors (or at least not any that are mentioned in the datasheet). Do you know if this could be used instead?
If the problem is the bleed resistors being in parallel when you combine all the outputs, what about flipping the MP4832A around the other way? The bleed resistors are only on the output pins, so if you combine all the input pins instead, and use the output pins as the 32 separate channels, you’ll have the 32:1 mux that you’re looking for. I’ve used similar parts in exactly this configuration for years successfully. Maybe you’ve considered this configuration already and dismissed it as non-viable for your use-case, but it seems to me like it could be a simple solution!
If you’re still looking for alternatives without the bleed resistors, and you’re OK with supporting only an industrial temperature range 0 to 70 degrees C), consider the Microchip HVxxxx series.