Types of switching power supplies
Constant voltage power supply and constant current power supply
There are many types of switching power supplies. First, it is divided into a “constant voltage power supply” that keeps the output voltage constant and a “constant current power supply” that keeps the output current constant. Just because it is a switching power supply does not mean that it is a constant voltage power supply.
LEDs and batteries are required to have a constant current, and the demand for them is increasing more and more these days. However, the manufacturers of constant-current power supplies are limited, and there are few types of constant-current power supplies, so there are many cases where you have to use a custom power supply.
Therefore, it may be used as a constant current power supply “simplely” by using the overcurrent protection function of the constant voltage power supply. With overcurrent protection, if more current flows than the rated current, the current value remains the same and only the voltage drops. When the current value drops and the overcurrent state disappears, the voltage value automatically returns to the rated voltage.
It can be used as a constant current power supply by changing the operating point of this overcurrent protection with a volume or the like. However, the operation of overcurrent protection is limited to the ” drooping characteristic” power supply, and it cannot be used as a constant current power supply in the “foldback current limiting characteristic” or “H-shaped method”. Only when the accuracy of the current value is rough and constant current control is sufficient.
Standard power supply and custom power supply
Switching power supplies include “standard power supply”, “catalog power supply”, “semi-standard power supply”, “custom power supply”, and “special order power supply”.
The standard power supply and the catalog power supply have the same meaning, and the power supply manufacturer sells the product specifications, dimensions, and data on the catalog and Homepage to an unspecified number of users.
To make it easy for many users to use, makers have obtained safety standards with average electrical specifications, and the shape and mounting are the standard size in the industry. Users can order from one unit, and can buy from the primary distributor, secondary dealer, local trading company, and online dealer of the power supply manufacturer.
The semi-standard power supply is a model with options added to the standard power supply. There are several options for each model. For example, options such as “ON/OFF control“, “variable output voltage volume”, and “vertical terminal block” are identified by adding alphanumeric characters such as R, V, and T at the end of the model name. As for the price, options are added, and the delivery time is about 1 to 2 months. It is wise to think of it as a made-to-order product.
Custom power supply and special order power supply have the same meaning. A power supply designed and manufactured for a specific user according to the specifications of the final product. Therefore, the electrical specifications and shape are special specifications that standard power supplies do not have. To put it the other way around, there was no suitable power supply for the standard power supply, so it can be said that it was unavoidably customized.
Custom power supplies have a variety of uses, but are mainly used in consumer equipment. Power supplies used in consumer equipment must be designed specifically for them due to strict restrictions on function, shape, size, and cost.
Test data and safety standards are costly, so users only get what they need. Custom power supplies should not be custom-made unless the number of units can be expected, as all design and development costs and standard acquisition costs will be borne by the user.
Generally, it is said that the minimum custom line is 500 or more units a month and 50 million yen a year. Custom power supplies often have trouble with the time of termination and the number of lots ordered, so it is necessary to state them firmly in the contract first.
Normally, “standard product = mass production = cheap” and “custom product = small quantity high variety = expensive”, but in the switching power supply industry, the opposite is true “standard product = small quantity high variety = expensive” “custom product = mass production = low price” It is said to be. It is true from the perspective of one user, but standard products are produced collectively by the power supply manufacturer by collecting orders from a large number of users all over Japan.