Five design skills of LED driver power supply
Abstract：At present, the use of LED constant current drive power and LED constant voltage drive power to more and more places, the market also contains huge potential for development, then in the design of LED drive power when what is clever? Optical password for everyone unified to do the answer.
At present, the use of LED constant current drive power and LED constant voltage drive power to more and more places, the market also contains huge potential for development, then in the design of LED drive power when what is clever? Optical password for everyone unified to do the answer.
First, do not use bipolar power devices
Bipolar power devices are cheaper than mosFET, generally about 2 cents, so some designers use bipolar power devices in order to reduce the cost of led driver power, which will seriously affect the reliability of the circuit, because with the increase in the temperature of the LED driver circuit board, the effective working range of bipolar devices will rapidly shrink. This will lead to the failure of the device when the temperature rises, thus affecting the reliability of LED lamps, the correct way is to choose MOSFET devices, MOSFET devices have a service life much longer than bipolar devices.
Second, the voltage of MOSFET should not be lower than 700V
Voltage 600V MOSFET is cheaper, many think that the input voltage of LED lamps is generally 220V, so the voltage 600V is enough, but many times the circuit voltage will be 340V, when there is a surge, 600V MOSFET is easy to be broken down, thus affecting the life of LED lamps. In fact, the selection of 600VMOSFET May save some costs but pay the price of the entire circuit board, so try not to choose 600V voltage MOSFET, better choose a voltage of more than 700V MOSFET."
Third, try not to use electrolytic capacitors
Do you want to use electrolytic capacitors in the LED driver circuit? Today, there is no consensus. Some people think that the input part of the LED drive circuit can be considered without electrolytic capacitors. In fact, the linkSwite-PH of PI can save the mind to remove electrolytic capacitors. The single-stage PFC/ constant current design of PI allows designers to eliminate large-capacity capacitors. In the output circuit, high-voltage ceramic capacitors can be used to replace electrolytic capacitors to improve reliability. Some people in the design of a two-stage circuit, in the output of a 400V electrolytic capacitor, which will seriously affect the reliability of the circuit, it is recommended to use a single-stage circuit with ceramic capacitors. Electrolytic capacitors are not recommended for industrial applications that are less concerned with dimming, high temperature environments, and require high reliability.
4. Try to use MOSFET devices
If the LED driver power supply is not very high for the designed LED lamp power, it is recommended to use an integrated MOSFET LED driver product, because the advantage of doing so is that the on-resistance of the integrated MOSFET is less, and the heat generated is less than the direct, in addition, the integrated MOSFET is the controller and the FET together. Generally have the overheating off function, MOSFET overheating will automatically turn off the circuit to protect the purpose of LED lamps, which is very important for LED lamps, because LED lamps are generally very small and difficult to carry out air heat dissipation.
Fifth, try to use single-stage architecture circuit
Some LED circuits use a two-stage architecture, that is, "PFC(power factor correction)+ isolated DC/DC converter "architecture, such a design will reduce the efficiency of the circuit. For example, if the efficiency of the PFC is 95% and the efficiency of the DC/DC part is 88%, the efficiency of the entire circuit is reduced to 83.6%!" PI's LinkSwitch-PH device simultaneously integrates the PFC/CC controller, a 725VMOSFET and MOSFET driver into a single package, increasing the efficiency of the drive circuit to 87%! Such devices can greatly simplify the layout of the board design, more than 25 components used in traditional isolated flyback design! The components omitted include high-voltage large-capacity electrolytic capacitors and optocouplings. The LED two-stage architecture is suitable for older drivers where a second constant current driver circuit must be used to enable the PFC to drive the LED constant current. These designs are obsolete and no longer cost-effective, so single-stage designs are preferable in most cases.
Through the above understanding, when designing the LED driver power supply, it is strictly guarded, and the products produced are durable and good quality.
First, do not use bipolar power devices
Bipolar power devices are cheaper than mosFET, generally about 2 cents, so some designers use bipolar power devices in order to reduce the cost of led driver power, which will seriously affect the reliability of the circuit, because with the increase in the temperature of the LED driver circuit board, the effective working range of bipolar devices will rapidly shrink. This will lead to the failure of the device when the temperature rises, thus affecting the reliability of LED lamps, the correct way is to choose MOSFET devices, MOSFET devices have a service life much longer than bipolar devices.
Second, the voltage of MOSFET should not be lower than 700V
Voltage 600V MOSFET is cheaper, many think that the input voltage of LED lamps is generally 220V, so the voltage 600V is enough, but many times the circuit voltage will be 340V, when there is a surge, 600V MOSFET is easy to be broken down, thus affecting the life of LED lamps. In fact, the selection of 600VMOSFET May save some costs but pay the price of the entire circuit board, so try not to choose 600V voltage MOSFET, better choose a voltage of more than 700V MOSFET."
Third, try not to use electrolytic capacitors
Do you want to use electrolytic capacitors in the LED driver circuit? Today, there is no consensus. Some people think that the input part of the LED drive circuit can be considered without electrolytic capacitors. In fact, the linkSwite-PH of PI can save the mind to remove electrolytic capacitors. The single-stage PFC/ constant current design of PI allows designers to eliminate large-capacity capacitors. In the output circuit, high-voltage ceramic capacitors can be used to replace electrolytic capacitors to improve reliability. Some people in the design of a two-stage circuit, in the output of a 400V electrolytic capacitor, which will seriously affect the reliability of the circuit, it is recommended to use a single-stage circuit with ceramic capacitors. Electrolytic capacitors are not recommended for industrial applications that are less concerned with dimming, high temperature environments, and require high reliability.
4. Try to use MOSFET devices
If the LED driver power supply is not very high for the designed LED lamp power, it is recommended to use an integrated MOSFET LED driver product, because the advantage of doing so is that the on-resistance of the integrated MOSFET is less, and the heat generated is less than the direct, in addition, the integrated MOSFET is the controller and the FET together. Generally have the overheating off function, MOSFET overheating will automatically turn off the circuit to protect the purpose of LED lamps, which is very important for LED lamps, because LED lamps are generally very small and difficult to carry out air heat dissipation.
Fifth, try to use single-stage architecture circuit
Some LED circuits use a two-stage architecture, that is, "PFC(power factor correction)+ isolated DC/DC converter "architecture, such a design will reduce the efficiency of the circuit. For example, if the efficiency of the PFC is 95% and the efficiency of the DC/DC part is 88%, the efficiency of the entire circuit is reduced to 83.6%!" PI's LinkSwitch-PH device simultaneously integrates the PFC/CC controller, a 725VMOSFET and MOSFET driver into a single package, increasing the efficiency of the drive circuit to 87%! Such devices can greatly simplify the layout of the board design, more than 25 components used in traditional isolated flyback design! The components omitted include high-voltage large-capacity electrolytic capacitors and optocouplings. The LED two-stage architecture is suitable for older drivers where a second constant current driver circuit must be used to enable the PFC to drive the LED constant current. These designs are obsolete and no longer cost-effective, so single-stage designs are preferable in most cases.
Through the above understanding, when designing the LED driver power supply, it is strictly guarded, and the products produced are durable and good quality.
