How to Easily Solve the DC/DC Power Module Common Failures? That is a problem for most of the engineers, today we are going to make some analyse.
# 1 The output voltage is too low
Circuit input voltage is too low, will make the circuit is unnormal, for example in the the microcontroller system, if the load suddenly increases, which will pull down the microcontroller supply voltage, resulting in reset. DC/DC Power module in the case of low input voltage for long time working, would have bad influence on the circuits life.Then, what’s the reason causing the output voltage too low ?
1) low input voltage or insufficient power;
2) output line is too long or too narrow, causing excessive line loss;
3) the anti-reverse diode voltage drop at the input is too large;Input filter inductance is too large
Solution
1) to increase the voltage or switch to a higher power input power supply;
2) adjust the wiring, increase the cross sectional area or shorten the wire lead length, reduce the internal resistance;
3) for the use of conduction voltage drop of small diodes;
4) reduce the filter inductance or reduce the inductance of the internal resistance
# 2. The input voltage is rather too high
If the input voltage is too high, easy to burn the whole circuit, causing greater harm, which normal reasons easily lead to such high voltage?
1) the output port is floating or no load;
2) output load is too light, lighter than 10% of the rated load;
3) Input voltage is high or has interference voltage.
Solution
1) to ensure that the output has not less than 10% of the rated load, if the actual circuit work has non-load , plus a fake load in parallel a rated power of 10% of the dummy load;
2) replace a reasonable range of input voltage, if exist interference voltage should be plus TVS tube or regulator tube in parallel at input.
# 3 The module serious in hot
Power converter in the voltage conversion process has energy loss, producing heat causing module become hot, reduce the power conversion efficiency, affecting the normal operation of the power module, but what condition will cause the power module heat more serious?
1) using a linear power supply module;
2) load over current
3) load is too small: the load power is less than 10% of the module power output power, will likely causing power module heat (efficiency is too low);
4) Ambient temperature is too high or poor heat dissipation.
Solution:
1) use a linear power supply to add heat sink;
2) increase the load of the power module to ensure that the rated load is not less than 10%
3) reduce the ambient temperature, keep heat well.
# 4 The output noise is large
Noise is a measure of the merits of the power module a key factor, in the circuits application, DC/DC power module design layout will also affect the output noise, what factors have a greater impact on the output noise?
1) DC/DC power module is too close to the mainly circuit noise sensitive components;
2) the main circuit noise sensitive components of the power input terminal is not connected decoupling capacitors;Differential frequency
3) interference occurs between the power supply modules of the single output in the multi-channel system.
4) Ground handling is unreasonable.
Solution:
1) isolate the DC DC power supply module from the main circuit noise sensitive element or module as far as possible with the main circuit noise sensitive components;
2) The main circuit noise sensitive components (such as: A / D, D / A or MCU, etc.) power input connect the 0.1μF decoupling capacitors;
3) use a multi-output power supply module instead of multiple single output module to eliminate differential frequency interference;
4) using a little remote grounding, reducing the ground loop area.