Detect triggered polyswitch/resettable fuse

rs2845

Senior Member
Hi,

I have been designing and prototyping a more reliable power supply for a project and have added in fuses to try isolate key areas to minimise the risk of overcurrent from any of the sub-circuits burning the entire thing out. I hope so anyway.

Is there any way I can use a Picaxe pin to determine whether one of my fuses have tripped? The fuses are rated to trip at 5A. I've seen some basic examples online and they have worked, but I am reluctant to connect to any sensitive IC's until I know they're safe.

Here's one example that i've got breadboarded (circuit 1):
https://dmohankumar.wordpress.com/2015/10/21/blown-fuse-indicators-simple-design-10/

Some of the supplies are going to draw between 3-4 amps at any time, so this is where I worry about just adding in a current limiting resistor and connecting to a Picaxe pin.

Here's a couple of screenshots of my early crude design (ignore the PIC32, using a Picaxe 28X2 to speed up development). Working on a design with an MCP23017 as I've run out of IO pins in this design.


2B-overview.png
2B-rev3.png
 

grim_reaper

Senior Member
For simple fuse monitoring I would just take a feed off your supply circuit immediately after the fuse to a resistor and an opto-isolator.
I use opto-isolators because it creates a neat segregation between 12V/24V and the PICAXE 5V circuit.
 

techElder

Well-known member
How about just using an LED that doesn't light up when the fuse is blown?

I have / had circuits of 1000's of amps and also some of milliamps and never "blew a fuse". Blowing a fuse is a sign of poor circuit design or abuse. Neither one can be solved by monitoring with a PICAXE.

PS. Yes, I already know I'm going to hurt someone's "feelings"; probably tmfkam.
 

tmfkam

Senior Member
I think current limiting is a vital part of any design. That could be traditional fuses, polyswitch fuses or simple low value resistors between devices and interconnected modules. I also strongly believe in indicating devices to show that certain parts of a design are/are not working. That could be a humble LED or a small flag raised on an LCD display.

Every day I am called upon to repair items of equipment where for the want of a resistor, fuse, thermal cutout or two, the devastation caused by misuse that would have taken minutes to repair has instead taken hours.

Today I have to replace a 144 pin SMD processor as the manufacturer decided to directly connect an SPI data bus directly from the processor pins to a remote display 3m away. This wire runs alongside some 48V PWM motor wiring, 48V PWM inductor wiring, out to a display mounted directly to a perspex panel that is polished when cleaned. At some point enough induced energy, whether static or cross coupled, is put into the wiring to fry the SPI ports on the processor. This design was in production for a number of years, yet the manufacturer never thought that including a few resistors and protection diodes would limit the damage to the SPI port. Madness.
 

premelec

Senior Member
i think Tex is leading some sort of charmed life... I've seen melted wiring harnesses, exploded capacitors, shorted power transistors etc... some from bad design some from wear and tear [automotive], some from apparent end of life from enough on/off cycles. Hooray for current limiting - beats overt fires... ;-0
 

rs2845

Senior Member
Thanks for the replies so far


How about just using an LED that doesn't light up when the fuse is blown?
As mentioned - I am.

I have / had circuits of 1000's of amps and also some of milliamps and never "blew a fuse". Blowing a fuse is a sign of poor circuit design or abuse. Neither one can be solved by monitoring with a PICAXE.
Perhaps this may be your experience. I can't imagine that practically every single electronics manufacturer has "poor circuit design". I'd rather protect the investment i've made in my hardware thanks.




Anyway..

I'm currently breadboarding circuit 1 from the link in my initial post, but I guess my question is.. How can I safely replace the blown fuse LED for a picaxe pin when the supply could be 5A (or I guess more if the supply fails somehow)? I'm guessing a 330R resistor on the picaxe pin (analogue or digital here?) would be insufficient.

I'll look into optoisolators but I am already over my budget and don't really want to be buying much more if I can avoid it.

The power supply I am developing is one small part of a larger control panel, where it'll return all the voltage readings, transistor states and fuse statuses to the main controller when interrogated. Faults will then be indicated on the HMI board also in development.
 

fernando_g

Senior Member
A third vote for an optoisolator. Swap the external LED with the optocoupler's internal LED.

Tmfkam: you are not alone. I've seen many cases like this.

In 1980 I was asked to fix a top-of-the-line Nakamichi Cassette tape recorder.
If you are as old as I am, you may remember that Nakamichi was the Ferrari of the Cassette recorders: very high performance, sleek design, and very, very expensive.
This particular unit was over US$1000 in 1980s dollars. One of the first ones to utilize a microcontroller for full tape transport operation.

Long story short: The Nakamichi engineers had decided, for reasons known only to them, to use the "PLAY" button's backlight bulb as a pullup for a particular I/O pin.
It never occurred to them that, being an incandescent lamp, it could burn out....and when it did, the lack of pullup resistor prevented the unit from doing anything, including ejecting the Cassete tape.
 

StefanST

New Member
Here's a couple of screenshots of my early crude design ...
View attachment 21404
View attachment 21403
Your circuit design is quite unusual:
(1) Capacitors are in series with fuses at the inputs of the regulator modules. I did not understand how the current flows.

(2) Transistors as a low-side switch will not work properly in the designed circuit!

(2a) I suppose, the Panel-module have common ground, i.e. all three "Supply 0V" (3.3V / 5V / 12V) are connected. So, all three transistors are connected in parallel. The same is valid for the HMI-Panel.
(2b) The voltage drop on the transistor ZTX851 NPN is Vcesat = 100mV at current 2A (or 200mV at 4A). It is too much.

(3) Resistors 1k+1k in the "Voltage dividier 40V=>24V" will not work. Why is the "3.3V PSU Supply" not connected to the 24V regulator?

(4) I don't know, why you should measure the voltage of all regulators. I think sufficient information is whether the voltage is within tolerance or not. There are "Supply Voltage Supervisor" IC's for that purpose. Then the simple combinational logic circuit with some flip-flops can controll individual regulators with it's Enable input pin. Independend power supply can supply this circuit with Leds indicating a malfunction. Well, yet another LEDs for simple fuse monitoring (on PCB next to fuses).

You are certainly good programmer, so you should look for somebody good in electronics to help you design the circuit correctly.
 
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tmfkam

Senior Member
Tmfkam: you are not alone. I've seen many cases like this.

If you are as old as I am, you may remember that Nakamichi was the Ferrari of the Cassette recorders: very high performance, sleek design, and very, very expensive.
This particular unit was over US$1000 in 1980s dollars. One of the first ones to utilize a microcontroller for full tape transport operation.
Would that be the "Dragon"? I remember them all too well! I never saw one, let alone owned one, but boy, did I want one!
 

rs2845

Senior Member
Your circuit design is quite unusual:
(1) Capacitors are in series with fuses at the inputs of the regulator modules. I did not understand how the current flows.
Yes I realised the mistake I made with the capacitors in this schematic. Corrected already, daft error.

(2) Transistors as a low-side switch will not work properly in the designed circuit!
How come? I followed this https://learn.sparkfun.com/tutorials/transistors/applications-i-switches which shows NPN transistors as a low side switch. The negative of the load feeds into the transistor?

(2a) I suppose, the Panel-module have common ground, i.e. all three "Supply 0V" (3.3V / 5V / 12V) are connected. So, all three transistors are connected in parallel. The same is valid for the HMI-Panel.
(2b) The voltage drop on the transistor ZTX851 NPN is Vcesat = 100mV at current 2A (or 200mV at 4A). It is too much.
2a. Not quite sure whether you’re proposing a change…
2b. Too much? Would you suggest an alternative transistor?

(3) Resistors 1k+1k in the "Voltage dividier 40V=>24V" will not work. Why is the "3.3V PSU Supply" not connected to the 24V regulator?
I made a mistake there with the resistor markings (copy-paste error) which I’ve rectified in a newer schematic. This 3V3 supply is solely for the power supply Picaxe. It needs to be operative even if the 24v supply goes down.

(4) I don't know, why you should measure the voltage of all regulators. I think sufficient information is whether the voltage is within tolerance or not. There are "Supply Voltage Supervisor" IC's for that purpose. Then the simple combinational logic circuit with some flip-flops can controll individual regulators with it's Enable input pin. Independend power supply can supply this circuit with Leds indicating a malfunction. Well, yet another LEDs for simple fuse monitoring (on PCB next to fuses).
I know those IC’s exist but they would take up quite a bit more space on my board, plus I don’t think I found any DIP package variants which I need for these early prototypes as I am a long way off getting proper PCB’s made. I’ll explore once again.

I’d rather not have to pull out a multimeter to check voltages to diagnose issues, I want my system to transmit a fault. I have to use an ADC chip to measure some voltages anyway, so may as well do them all.

You are certainly good programmer, so you should look for somebody good in electronics to help you design the circuit correctly.
This is my first real electronic project so it’s a huge learning curve, this is a Picaxe forum so didn’t think it was appropriate. I welcome any and all critique though so I can improve the design.
 

AllyCat

Senior Member
Hi,

How come? I followed this https://learn.sparkfun.com/tutorials/transistors/applications-i-switches which shows NPN transistors as a low side switch. The negative of the load feeds into the transistor?
I have to agree that the circuit design looks very "strange".

It would be very unusual to use a "low side switch" to (control) a regulator, because normally a regulator needs a "perfect" earth. If the reference/earth is "poor" then so will be the quality of its output. Also. you show separate input and output "negatives" (earths), but the chip appears to have only one, and how/where are its peripheral components connected? If the "In-" and Out-" are actually connected together, then that should be shown in the diagram.

The NPN transistors on the right-hand side can only act as low-side switches if all the "Supply 0" (normally considered to be "Earths") are independently isolated and "floating", which at the very least could be "confusing". The MP1584 appears to have an "Enable" input, can't you use that?

Cheers, Alan.
 

Reloadron

Senior Member
For simple fuse monitoring I would just take a feed off your supply circuit immediately after the fuse to a resistor and an opto-isolator.
I use opto-isolators because it creates a neat segregation between 12V/24V and the PICAXE 5V circuit.
I would also work around the same, a circuit using an opto-isolator. Similar to your links but replacing the LED with an opto-coupler or isolator. This affords isolation between your data for fuse failure and the actual monitored circuit.

Ron
 

StefanST

New Member
in Post #12 (rs2845 01-08-2017, 19:06 )
StefanST: (2) Transistors as a low-side switch will not work properly in the designed circuit! ...
rs2845: I followed this (URL link) which shows NPN transistors as a low side switch. The negative of the load feeds into the transistor?
Well, NPN transistor is good for isolated load as a LED, light bulb, relay, or DC motor.

Usually, input and output signals in logical circuits are mostly defined as a voltage with respect to ground level.
Conclusion: The ground is only one, and common.
Note: There are exceptions. You can distinguish more grounds, for example signal ground and power ground. They are on the same potential and differ only in the reduction of the ground noise and disturbances in sensitive devices. More - see Wikipedia about Ground(electricity) in the section Electronics.

StefanST: (2b) The voltage drop on the transistor ZTX851 NPN is Vcesat = 100mV at current 2A (or 200mV at 4A). It is too much.
rs2845: 2a. Not quite sure whether you’re proposing a change…
2b. Too much? Would you suggest an alternative transistor?
Yes. Too much. Even 100mV in 3.3V logics cause worsening noise immunity.

An alternative to the low-side switch is the high-side switch. There are high-side switch ICs. You can see MIC2544 or MIC2545 datasheets for example. Another alternative is the enable pin in case of the power supply. Your MP1584EN has the enable pin to switch on/off the power supply.

StefanST: (4) ... There are "Supply Voltage Supervisor" IC's for that purpose. ...
rs2845: I know those IC’s exist but they would take up quite a bit more space on my board, plus I don’t think I found any DIP package variants ...
You can use tiny PCB reduction of the SOP device to DIP pins.

rs2845: I’d rather not have to pull out a multimeter to check voltages to diagnose issues, I want my system to transmit a fault. I have to use an ADC chip to measure some voltages anyway, so may as well do them all.
To create a reliable system, as you said, it is better to prevent predictable malfunctions and prevent HW damage due to any errors. You can create a supervisor and diagnostic module (and its software). Its main roles are:

(a) Avoid damage or malfunction of the system: Safely controlled shutdown of the entire system.

(b) Avoid damage or breakdown of the controller (HW) for most possible malfunctions.

(c) On the first level, the system only displays basic information about errors to the end users. End users are permitted to replace the mains fuse only. If the system does not work, the entire system (HW / SW) should diagnose and repair service personnel. They have necessary diagnostic tools. Or replace the suspicious modules as they do with computers.

(d) On the next level, module displays detailed system status information . This helps diagnose the problem or detect a bad module or component. Module can diagnose a limited set of predictable problems. Built-in diagnostics can help, but it is difficult and expensive to build such a system.
 
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StefanST

New Member
in Post #1
I have been designing and prototyping a more reliable power supply for a project ... ... to minimise the risk of overcurrent from any of the sub-circuits ...
This post is a continuation of # 10 ( StefanST 29-07-2017, 01:36)

Specification
The written specification, all the requirements of the entire project will help you in designing. This will also help in this forum - in finding answers to some specific problems in the context of the project.


The overall picture of the project
(Helps to understand the role and requirements for modules)

(5) Can you publish the entire schema or modular scheme of the projected device? Its functionality, the project aims, etc. (There are different requirements for a space probe project than automation of a Christmas tree.) How limited is the budget?

(6) What should be the whole system strategy for any failure? Are there any predictable errors that require specific system behavior?

(7) Are there critical modules, components, power components or external components that could cause unacceptable problems or failures?


The reliable power supply
(this one is in the focus of your thread)

(8) Specify in detail all the required parameters and behavior of the power supply in the context of the entire application.

(9) Specify the behavior of the power supply for various application faults and anomalies.

rs2845: Some of the supplies are going to draw between 3-4 amps at any time ...
(10a) You can at least complete a scheme with the values of max.currents consumed by the individual modules, i.e. HMI @ 5V, 3.3V, Panel @ 12V, 5V, 3.3V, and Loop Device @ 40V. Not exact values, just give 100mA/200mA/500mA/1A/2A/5A/or more.

(10b) What tolerances and ripple of output voltages are required?

(10c) Is it required overload protection? How quickly it should react? Is it necessary to limit the current or completely disconnect all outputs?

(10d) Will the individual outputs be connected individually or all at the same time when the power supply is switched on? (If individual, why?)

(10e) Other requirements (indication that all outputs are OK, individual outputs are OK, ...)

rs2845:... The fuses are rated to trip at 5A. ...
(10f) All fuses are the same 5A? The schema does not contain this information.

(11) Is the design of the system compact or are there distances between modules greater than 30 cm? (Question about ground conductors)
 
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Dave Spider

New Member
Hello StefanST,
I am with all the old timers that saw the Nakamichi money makers. I have seen tons of circuits to "Protect the power supplies in Consumer and Professional equipment over the many years. Some work to a point and some do nothing. The best ones are Opto-isolators that not only protect the power supply, associated circuits and the processor. I have never seen a Yamaha unit to smoke as most equipment made today do. Opto's can use a common point ground to prevent many problems unlike other methods of common (not common ) grounds spread through the unit.

Stefan, there is one rule you must consider, The fuse blows AFTER the components it is there to protect. If you look at the specification for a normal fuse it takes a very long time to blow at it's rating and much more current than you wanted to travel down the PCB traces. Inrush current is something to consider when sizing fuses. I do know that the question you asked is not an easy one to answer, there are so many factors to consider, Price, board space and programming time to debug is only scratching the surface of the answer. The lowest cost method I have seen that does do the job well is a low ohm resistor (flame proof) that will open quickly without further damage to the
supply electronics. Oh yes, do not mount these resistors tight to the PCB. Stand them off double the dia of the resistor.
 

Dave Spider

New Member
RS, switching the low side is a really bad move. The load circuits will find a path to ground someway and create a mess of a problem. The ZTX transistors switching the secondary power is not good also. Too much voltage drop at higher currents. Use a regulator IC that has a On/off pin.
 

StefanST

New Member
Hello Dave,
I agree with you.

As RS said "This is my first real electronic project so it’s a huge learning curve,...", so we should be patient. That is why I tried to highlight the wrong steps and suggest a way to make a better design and thus the possibility to involve forum members in this help.
 

hippy

Technical Support
Staff member
Stefan, there is one rule you must consider, The fuse blows AFTER the components it is there to protect.
My understanding is that fuses are there to protect the supply, not the components or circuit with the fault condition - though I think you were, other than in this sentence, saying that.

Thus a fault in a home electrical appliance blows the fuse in the plug, protects the ring main from over-current, heating and fire. The fuse at the meter stops a household fault affecting the street feed, the local substation etc.
 

rs2845

Senior Member
Hello all,

Thank you for the responses, haven’t forgotten about this thread, just haven’t had enough time recently. I am going through all replies slowly to ensure I don’t miss anything.

Clarification: I am familiar with electronics, but literally just for working with micro controllers and circuits =<12v. This is the first project that I have had to work with higher currents and voltages so I welcome any and all input. Last thing I want to do is have it catch fire!

Quick updates:

  • Scrapped the diagrams/design attached to my original post as there were some flaws with the supplies.
  • Will use optoisolators, makes sense now I know what they are.
  • Using transistors as low side switch abandoned. I understand why now.
  • Will be using the Chip Enable line on my MP1584EN and LM2596HV modules. Not pretty, but for a concept prototype it will do.
  • Fuses are now 2.5A but will fire at 5A.
  • Will use MCP23017 to control each Chip Enable line allowing better control over each voltage output.



Project Information:
Below is a diagram of the control panel as a whole (note: this thread relates only to the Power Supply Management Module). On August 30th I will have sufficient time to complete a new schematic, incorporating the above, which I will post here then - would appreciate any input when I do!
DIAGR-001-INT-001.png
 

StefanST

New Member
... haven&#8217;t forgotten about this thread, just haven&#8217;t had enough time recently. ...
Thank you for your response.

For the subsequent consideration, I am still awaiting the answer to question #16(10a) about needed currents.
Still just an estimate. It may be in the resolution 1-5-10, i.e. <100mA, <500mA, <1A, or more than 1A. For each module and voltage.
 

rq3

Senior Member
My understanding is that fuses are there to protect the supply, not the components or circuit with the fault condition - though I think you were, other than in this sentence, saying that.

Thus a fault in a home electrical appliance blows the fuse in the plug, protects the ring main from over-current, heating and fire. The fuse at the meter stops a household fault affecting the street feed, the local substation etc.
As a general rule, the rating of a fuse or circuit breaker is to keep the wires or circuit board traces feeding it from starting a fire. This is GENERALLY true whether the wires are in a house, an automobile, or an airplane.

Protecting the supply is usually not economically possible, nor should it be, unless the supply is very, very expensive and local. In the case of a house, the supply is the generator somewhere very far down stream. In the case of an automobile or airplane, the supply is a lead-acid battery capable of many hundreds of amperes of short circuit current.

In both cases, the fuse or circuit breaker is there to keep the wires or circuit board traces from getting hot enough to cause catastrophic damage to their surroundings (like starting a fire).

Having said that, it IS possible to design overload detection circuits that trigger within picoseconds, or at least a few nanoseconds. Usually, the cost of these designs far exceeds the value of the devices they are intended to protect, and if they work, can you be sure they worked well enough to trust what remains after the event?

Usually, blowing a fuse, triggering a circuit breaker, or forcing that condition with a triggered over-current detector means that something went catastrophically wrong. The fuse is meant not ONLY as a protection device, but a signal that something needs to be fixed BEFORE the fuse is replaced.

In aviation, if a fuse blows or a circuit breaker pops, the general rule is that you are allowed one attempt to fix the issue (one fuse replacement, one circuit breaker re-set). Fuses and circuit breaker do, themselves, randomly fail. If the fix fails, back-up systems or methods come in to effect.
 

rs2845

Senior Member
Firstly, apologies for the delay. Been very busy with other commitments and university starting again.

Still working on this power supply design, thanks for the continued feedback.

Here is a newer revision (apologies, it looks very "busy", but the colours help me understand it). It hopefully answers @stefanST's question about the current consumption for each module. Hoping I haven't made any dumb errors, but it's likely.

Can anyone find any flaws in this version that could bring the house down? Quite literally.


(download the image here if you want)
DIAGR-002-INT-001.jpg
 
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StefanST

New Member
Hi Rav,

Your proposed version in #24 don't contain errors, that were in the previous one. But it seems still too complicated.

In the following, I am introducing a simplification of the Power supply module. Three different levels.
It's just my insight - it may not be the only one nor the best. You can adopt those parts you consider usefull.


Power supply
The main function of the power supply is to provide the required voltage at the currents from zero to specified maximum. Overloading or shorting limits the current (and voltage) and reports power failure. It also informs about voltage drops. No further functionality is necessary.


Simplification phase 1:
-------------------------
(A) The polyswitch fuse connected to the 5V / 3.3V outputs of the regulator is not good solution. See the datasheet. How much is the voltage drop on the fuse?

(B) Polyswitch and classical fuse are too slow to protect the electronics. They can protect (as additional protection) the power source and the next connected regulator over long overload.

(C) I do not think polyswitch fuse monitoring is needed. If you measure the voltage before and after the regulator, then you know whether the regulator is ok or not.

(D) I think standard fuse is a better solution. If the circuit fails, the fuse is interrupted. Required switching regulators should be resistant to overload and short circuit. The fuse will only respond if the switching regulator is damaged. An LED may be added to the blown fuse indication.

(E) This power supply module is a bit overcrowded with switching regulators. I think only three regulators 12V, 5V and 3.3V are enough in this module.
- The 12V sounder circuit should be used instead of the 24V. Is it possible?
- The relay can be powered together with the LEDs.
- MCUs and other devices can be powered by one common 3.3V power supply.
? Are there any relevant reasons why to feed each module with a separate source?
=> I propose to merge two 5V power supplies into one common one. And 3.3V power supply also.

(F) I do not see the reason, why to do a three-step conversion:
230V AC -> 48V DC -> 24V -> 12V / 5V / 3.3V
=> I suggest a simple configuration with three switching voltage regulators (instead of 10):
230V AC -> 12V -> 5V / 3.3V

(G) I added a Hi-side switch to the 12V supply. The switch also turns off when the current is exceeded. (But for the connected printer, only a fuse is enough.)

(H) All three switching regulators have added overvoltage and undervoltage monitoring. The MAXIM ICL7665 Supervisor IC can do it. (Or with two comparators.) Why? We do not need to know the exact regulator's voltage - just know if it is within the required range.

(I) For this type of application it is best to turn off all power sources. To be fast, we assume a "Control Logic" based on logical elements (flip-flop, NAND, NOR gates). This "Control Logic" controls ChipEnable of the MP1584 and Hi-side swith 12V.
Picaxe monitors the state of the voltages and the power-fail signals. Then controls LEDs, sound signals (piezo) and disconnects the power cable with a relay. Or can reset the system if there is only a short drop in the supply voltage.

(J) Picaxe, control logic and relay are powered by an independent power supply with a short-circuit-proof transformer (approx. 2W) and a LF33 IC voltage regulator.

The block diagram of the Power supply module is in figure 1, an example of "Control Logic" is shown in figure 2.
ST_Power Supply Module Ver.1 2017.10.10.jpg
PICAAXEFORUM - (1- ZDROJ ) - CONTROL LOGIC.png
StefanST
 
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StefanST

New Member
Simplification phase 2:
-------------------------
(A) We can use a switching power supply with 3 outputs: 3.3V / 5V / 12V instead of power supply 230V AC / 12V DC and two DC/DC converters.

(B) The second change is to replace the fuses with the MIC2544/48 (Hi-side switches with current limiter and adjustable current-limit up to 1.5A). We have to find an IC with a 4-5A limit, or use more such ICs.

(C) It is necessary to decide if the 5V source needs a Hi-side switch or just a fuse.

(D) Supply voltage monitor ICs, the Control logic module and Picaxe are the same as in previous version.

The block diagram of the Power supply module is in figure 3.
ST_Power Supply Module Ver.2 2017.10.10.jpg
 

StefanST

New Member
Simplification phase 3:
-------------------------
(A) Since we have the switching power supply with 3 outputs: 3.3V / 5V / 12V, we have to find such power supply module that contains other required properties and behavior:

The module diagram is in figure 4.
ST_Power Supply Module Ver.3a 2017.10.10.jpg

Switching Power Supply Requirements:
.....................................
Input: 230V AC (100-260)
Output Channel 1: 3.3 VDC >= 4A
Output Channel 2: 5 VDC >= 5A
Output Channel 2: 5 VDC >= 2A

* Adjustable main output:
* Overvoltage protection:
* Overload protection on all outputs:
* Short circuit protection on all outputs:
* Thermal overload protection
* No minimum load required
* Undervoltage indication (in power-fail?):
* Power fail indication

As a first iteration we can see LPT101-M Datasheet:
http://www.mouser.com/ds/2/633/lpt100-m_ds_05-04-2014_e2ffa03c50-595376.pdf
or
http://www.mouser.sk/ProductDetail/Artesyn-Embedded-Technologies/LPT101-M/?qs=sGAEpiMZZMsPs3th5F8koKzyWognMsNU%252bcntsLg9EUw%3d

_LPT101-M Artesyn Embedded Technologies _ Mouser .png


The offer is wide, just look up the proper model.


The "Power Fail Indicator" is powered with 12V/5V/3.3V if the Power Supply has any voltage.
If no one has any voltage, the indicator is not active.

StefanST
 
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