Can a 12V 20A SMPS be used interchangeably with a 24V 5A SMPS if the total wattage is the same?
                     Can a 12V 20A SMPS be used interchangeably with 
a 24V 5A SMPS if the total wattage is the same?
When working with electronic devices and power supplies, one of the fundamental considerations is ensuring 
that the power supply matches the requirements of the device. Switching Mode Power Supplies (SMPS) are 
widely used in various applications due to their efficiency and compact design. A common question that arises is 
whether a 12v 20 amp SMPS can be used interchangeably with a 24V 5A SMPS if the total wattage output is the 
same. To answer this question, we need to delve into the principles of power, voltage, and current, and 
understand the specific requirements of the devices being powered.
Understanding Power, Voltage, and Current
Power (Wattage) is the rate at which energy is consumed or produced. It is calculated as the product of voltage 
(V) and current (A). For an SMPS, the formula is:
\ [P = V \times I \]
Where:
- \ (I \) is the current in amperes (A).
For the two SMPS units in question:
- A 12V 20A SMPS has a power output of 240W (12V * 20A).
- A 24V 5A SMPS also has a power output of 120W (24V * 5A).
At first glance, it may seem logical that if the wattage is the same, the power supplies could be used 
interchangeably. However, several critical factors must be considered before making such a substitution.
Voltage Compatibility
The primary concern when considering whether one SMPS can replace another is voltage compatibility. Using a 
power supply with a voltage that is too high can damage the device, while using one with too low a voltage can 
cause it to malfunction or not work at all.
For instance, if a device is designed to operate at 12V and you use a 24V power supply, you risk causing 
significant damage to the internal components. This is because the higher voltage can lead to excessive current 
flow through the device's circuits, potentially overheating and damaging sensitive components.
Conversely, if a device requires 24V and is supplied with only 12V, it may not receive enough power to operate 
correctly. Some devices have a certain tolerance for voltage variations, but exceeding these limits can result in 
operational failures or underperformance.
Current Requirements
The current rating of an SMPS indicates the maximum current it can supply without overheating or becoming 
damaged. While the wattage output of both the 12V 20A SMPS and the 24V 5A SMPS is the same, the current 
they supply at their respective voltages differs significantly. 
A device requiring a 12V input might need up to 20A to function correctly if its total power requirement is 240W. 
If you substitute this with a 24V 5A SMPS, the device will only receive a maximum of 5A, which, due to the 
different voltage, may not meet the device’s needs even if the total power is sufficient.
Power Distribution and Efficiency
Different devices have different power distribution and efficiency requirements. SMPS units are designed with 
specific internal components and circuitry optimized for their output voltage and current. Even if two SMPS units 
have the same wattage rating, the internal design differences can affect how efficiently they deliver power to 
connected devices.
Using an SMPS with a different voltage rating than required can lead to inefficient power distribution, potentially 
causing overheating or reducing the lifespan of both the power supply and the connected device. Additionally, 
the efficiency of an SMPS can vary depending on the load and the input voltage. This variation can impact the 
overall energy consumption and heat generation.
Safety Considerations
SMPS units come with built-in protections like over-voltage, over-current, and short-circuit protection. However, 
these protections are designed within the context of the SMPS's rated voltage and current. Using an SMPS 
outside of its intended specifications can negate these protections and create safety hazards, such as electrical 
fires or equipment damage.
Conclusion
In summary, while a 24v 5 amp SMPS may have the same total wattage output, they are not interchangeable if 
the voltage requirements of the device are not the same. The voltage difference alone can result in device 
damage or malfunction. Furthermore, the current supply capability, power distribution, efficiency, and safety 
features are all factors that prevent these SMPS units from being used interchangeably.
When selecting an SMPS for a particular device, it is crucial to match both the voltage and current requirements 
of the device. Always refer to the device's specifications and consult with the manufacturer or a qualified 
electrician if you are unsure about the compatibility of a power supply.
Ultimately, using the correct SMPS ensures that your devices operate safely and efficiently, protecting both your 
equipment and your investment. Therefore, it is not advisable to substitute a 12V 20A SMPS with a 24V 5A 
SMPS, or vice versa, even if the total wattage is the same.
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