A power supply IC is an integrated circuit (IC) that contains one or more linear regulators and DC-DC converters. The IC also contains protection and control functions for the power supply .
There are many different types of power supply ICs , from simple ones equipped with just a few power supplies to complex ones equipped with 10 or more power supplies and control functions. Therefore, when using one, it is necessary to select the power supply IC that is best suited to the system you want to use .
Figure 1 Example of a power supply IC (NXP PF9453)
If you can successfully select the optimal power supply IC, it will lead to easier power supply design and a reduction in the mounting area, but if you cannot, it may be necessary to add extra external circuits or control across multiple ICs, making the design more difficult.
When selecting the optimal power supply IC, the best procedure for narrowing down the list of candidate power supply ICs can be summarized in the following three steps.
・Step 1 - Selecting candidate power supply ICs
・Step 2 - Check the mounting area
・Step 3 - Check the thermal design
These steps involve actually creating a tentative design for the power supply circuit.
So, let's take a look at Step 1 in this first installment.
Step 1 - Selecting candidate power supply ICs
Step 1-1: Check the voltage and current values input to the target system
- For automobiles, there are 12V ( passenger cars ) , 24V ( commercial vehicles ) , and 48V ( for high-power units ) .
- For industrial machinery, 24V , 12V , 5V , etc.
- For consumer use, there is the USB PD standard.
- Pay attention to the minimum input voltage (voltage fluctuation test conditions, etc., which vary depending on the application).
Step 1-2: Determine the components to supply power
- Determine the devices and quantities of components (microcontrollers/processors, communication transceivers, sensors, etc.) that make up the target system.
- The order in which the power is turned on and off is specified by the component.
Step 1-3: Classify the voltage system (current system) required for the target system
- Voltage systems are classified into 5V , 3.3V , 2.5V , 1.8V , 1.25V , etc.
- It is also necessary to classify devices into those that supply power constantly and those that supply power only under certain conditions.
- Also pay attention to the power-on/shutdown sequence.
- Don't confuse steady-state current (DC ) with peak current (AC).
Step 1-4: Search for a power supply IC
- Search online or through our in-house parts list.
- Pay attention to the shape of the package.
NXP's " PMIC & SBCs " page allows you to search for devices using the product selector , or to search for power supply ICs suitable for various microcontrollers /processors . You can also search by other companies' part numbers using cross-reference .
Step 1-5: Select a candidate power supply IC
- A few types remain as candidates.
- We are also considering cases where multiple power supply ICs are used.
Step 1-6: Check the peripheral components required for the candidate power supply IC
- From the recommended components, select FETs (field effect transistors, switches), coils, capacitors, etc. Be especially careful with FETs and coils, as they are large components.
- If there is a range of parameters for available parts, select the optimum one using a Bode diagram or similar.
Step 1-7: Create a BOM (Bill of Materials) and calculate part costs
- Calculate part costs from the BOM (bill of materials).
At this point, the total component cost, including the power supply IC and peripheral components, is determined, making it possible for the first time to make cost comparisons on a BOM basis.
In Part 2, we will explain " Step 2 - Checking the mounting area ," and in Part 3, we will explain " Step 3 - Checking the thermal design, " so be sure to check them out.
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When selecting the optimal power supply IC, the best procedure for narrowing down the list of candidate power supply ICs can be summarized in the following three steps.
・Step 1 - Selecting candidate power supply ICs
・Step 2 - Check the mounting area
・Step 3 - Check the thermal design
*In this first session, we will explain Step 1.
(Reading time: 5 minutes)