Voltage regulator getting hot

[CAI_Support]

We just got another replay from Microchip that the chip can operate in 55C environment without losing its reliability.
We need to dig more about it and let our users know.

 

[CAI_Support]

Microchip provided its chip testing result table.
Derated temperature is 55C without active cooling. Temperature is ambient in degree C.
 

 

[NeverDie]

FWIW, the linear regulators on arduino boards can get hot too.  However, it's easy to bypass them and avoid their heat entirely by providing your own regulated power to the board (either through USB or via the board pins set aside for that purpose) from somewhere else.  Anyhow, just passing through, but thought I'd mention that, as maybe there's a similar easy workaround of the same kind for this board too.
 
What voltage is the voltage regulator outputing anyway?  If it's something standard, like  5 volts, there's a plethora of external regulated power supplies to choose from, and you may already even have some lying around that you could use.  It's pretty simple.  Other than voltage and current requirements and possible voltage ripple, there's not much else you'll likely need to consider (except maybe power factor (?), if a motor is being controlled).  I'm just trying to say that if the heat is causing you to fret, just remove it from the equation and move on.  You'll sleep better at night.  Whether you actually need to remove it or not, well that's a different question entirely, although I guess it's the one you all are presently most focused on.
 
Sorry in advance if I completely missed the point.

 

[CAI_Support]

The voltage regulators are 5V and 3,3V. The one can get hot is 5V. If you have reliable 5V power, it can be directly connected to the humidify sensor or temp sensor terminal, which is 5V.  The input voltage through power terminal has protection for reverse power connection.  however, directly feed 5V to the board will not have that protection.  If wiring wrong on that will result immediate damage to the board.  We will not warranty on reverse voltage damaged board.
 
The discussion here is the CPU temperature on board also.  From latest information we obtained from Microchip, CPU in vertical installation with free air flow can stand up to 55C with everything operational. Once ambient temperature reached 55C, it either needs to reduce frequency, shutdown part of the function in CPU, or add additional cooling to cool off the CPU.  Microchip published testing data includes stress testing up to 150C and bake test to 175C.  Microchip insists on that  their chip will not be damaged operating in ambient temperature up to 85C.
 
Microchip did not provide us the max junction temperature.  We are working with them to obtain that, so that we can provide what kind of cooling is required to work in the full -40C to +85C temp range.  Since they provided us 55C as derated temperature, we would recommend customers with ambient temperature beyond 50C to add active cooling turning on at 50C, for example, a little fan to blow to the top the board, or replace the heatsink with a larger one.

 

[CAI_Support]

nitin100,
 
We are still working with Microchip to get answer to your problem. While we are waiting, we can offer you to rework your board to fit on a 3.0V regulator to replace the 3.3V onboard, in that way, the MC will be a lot cooler, and it will be able to operate in the temperature range you desired.  WC8's MC can work from 2V to 3.6V, with lower the voltage the less the heat.
 
This particular MC has both CPU core and PHY inside.  The CPU core part draws only 30mA, but the PHY part draws 170mA.  By reducing the voltage 10%, the heat generated will be probably 20% less.  We tested board working fine with 3V power to the MC.  In the future, we may also introduce feature to shut off Ethernet with certain external pin, in that way, it will be able to operate in full 85C range.
 
WC32 MC has its PHY in a separated chip, that MC spec is from -40 to +105C, so that WC32 can work in full 85C range without problem.  By default, we do not add heatsink to WC32 MC.  For people really need to work up to 85C temperature range, we would recommend to install a heatsink on both MC and PHY chip anyway to enlonger its life.

 

[CAI_Support]

Microchip answered saying +55C derated was when chip continuing working 250 years lifespan. At +150C, it has life span 6.8 years.  They insisted on that this MC will work at +85C with all subsystem on.   They said if this particular board did not work at 85C, they want to examine it.
 
Nitin100, if you could please send that board back to us, we will send you a replacement board, then we can forward that board to Microchip for them to examine the problem.  Thanks.

 

[pittom]

In the summer 2 of my boards run at +53C and never had a problem, could just be he is one of the lucky ones that got a bed chip