What is the maximum DC supply voltage rating of this solenoid driver board?
The product description shows it’s for 12V DC input, but I did not find any details on the safe Min Max range. How high and low can the input voltage be? Also how much noise or voltage spikes can it tolerate on its input?
A Tantalum capacitor exploded earlier then week on one of our many MCP23017 boards. The capacitor appears to be for the board’s input power regulator. It is located on the front left of the board.
We are using many of these boards with a Solar Panel Charged LI-Ion battery system. There can be a wide range of power voltages as the battery cycles on its charge - discharge cycles from 16V up to 20V.
We recommend 9-15VDC as the voltage range for these controllers, higher voltages and spikes can cause cap combustion. Please let us know if you have more questions.
Thank you Ryan1 for your prompt reply.
More analysis of the capacitor that exploded on one of our MCP23017s shows it was the 47uF 25V rated tantalum capacitor associated with the 5V step-down converter on the front left of the board. This board did not have any other I2C loads connected to its output I2C connector. There were no solenoids connected to any of the channels. This was just a lab test to test the timing of the controls to each channel. All channels operated normally until the failure of the cap,
At the time of the failure the board was in operation for many days with input voltage from a Li-ion battery that cycled from about 16V to a maximum of about 18 volts at the time of failure.
We need a solution now to operate our many MCP23017s reliably. Do we really need to limit the input voltage to 15V ? This was not clear when we first purchased these boards. What if we limit the board’s input to 16V using a well controlled and filtered regulator? Would there be any advantage to adding loads to the output I2C 5V line. Other boards that have many NCD I2C sensors attached have not failed in the last 2 years.
Considering a custom design - Ideally, we would like to have this board in a version that can work with a Li-ion battery that cycles from 17.5V to 21V Max.
It would be nice if we could get
- an input voltage up to 24V using a similar buck converter to that shown on TI’s LM2675 data sheet with fixed resistor feedback (page 19)? Or
- a version of this board without its limited 5V regulator or if we could bypass it completely? If so we would use a separate 5V buck regulator from 3rd party.
This device was designed to operate at 12VDC, all components are tuned for this on the controller (with a Max voltage of 15VDC (the wiring diagram typically shows the input voltage range).
Raising the voltage is possible, but we will need to examine each component in the design for this (including the caps). I cannot speculate on what caused the capacitor to fail, but I would be happy to examine the board. I really think we can increase the voltage range of the on-board capacitors to reach your target voltage, however, we make many MCP23017 boards, so I am not exactly sure which board you are referring to (see if you can get me a part number and I will dig a little further into this for you).
The board with the cap that exploded was one of our many “MCP23017 16-Channel 8W 12V FET Solenoid Driver Valve Controller with I2C Interface”.
It has standard connections and lists for $174.95 ea.
Other markings: I2CDVR8W16. SKU: PR20-4. UPC: 689860065086.
Question 1): What is the best way to send this bad board back to you?
We love these boards and NCD’s Quality, but we have an application where we need higher voltage input (input can range 16V to 24V). We’d like to keep the same standard I2C and power input connections. We would like to see this 24V version in your catalog also so more people can buy it for use in 24V industrial systems as well as for Solar powered Li-ion systems popular in RVs and remote applications.
Question 2): For our new higher voltage projects, what are the next steps for you to make a 24V board based on your existing 12V design that has proven successful in our existing field installations ?