DC DC Converter

Hi,
I made a small device to be fitted in vehicles. Some vehicles are with 12 V supply while others with 24V. So I plan to use a DC-DC converter like the one
https://www.sunrom.com/p/high-voltage-input-dc-dc-step-down-switching-regulator-based-on-lm2576hv
It is working well when tested at office. My doubts are

1. Will the high spike voltages in vehicles will cause failure of these type of supplies.
2. Are they less reliable than series regulator power supplies?

That module seems to be an effective solution, what equipment are you running from the 12v supply?

To improve imunity to spikes, I would add a small inductor to the 24v input line, the inductor in conjunction with the capacitors on the input circuit of the module will go a long way to damping any spikes.
You could also add a 30 or 35v zener diode to clip the spikes.

Less reliable than a series regulator?
From a purely statistical point of view, it is more complex and so it will be more prone to failure.
From a practical point of view you would probably never notice the difference unless you built a lot of each type and used them in the vehicles to test them.

JimB

1. Yes. Add transient suppressor diodes (Tranzorbs) to the input, and a power diode from the output to the input (anode to the input).

2. What you have *is* a series regulator. If you meant more reliable than a linear regulator, then I don't think the switcher design is inherently less reliable. Switching regulator circuits have more parts and more solder connections,. but generate less heat. It is not a simple or easy comparison to make, and depends on the specific design and manufacturing details of both approaches.

ak

Remember that a vehicle power has noise on both ground and positive.. The only way to have less noise on the ground ( vehicle chassis ) is to keep the negative wire as short as possible and to the nearest earthing point..

Behind the dash is the noisiest place ( electrically ) than anywhere.....

Thank you all for the replies

JimB said:

what equipment are you running from the 12v supply?

Click to expand...

A microcontroller based Alcohol Sensor

I'd like to see that pls!

The lm2000 series are fairly robust, there doesnt look to be any protection or filtering on that board so a tranzorb or mov would be a good addition.
I put together a circuit that did this, but it was much more rough and ready, I wanted to run a 28v 250w spotlight off 12v, the circuit worked however the bulb ran directly off high frequency ac from the o/p of the transformer.

P.S. I assume the sensor runs at a lower voltage than 12v, if so why step up to 24 then back down again, how about making a power supply regulator than can operate from 12v up to 24v.

I would assume the power required by this device is relatively small so why not just use a 12V low-dropout linear regulator that works from a 24V to 12V input?

crutschow said:

I would assume the power required by this device is relatively small so why not just use a 12V low-dropout linear regulator that works from a 24V to 12V input?

Click to expand...

Take some 400mA current as there are 2 small fans and a heater.