Conversion from an intermediate rail voltage, such as 48 V, to lower voltages like 12 V or 5 V is less efficient when using a conventional buck converter. A more effective solution is a hybrid converter, which uses an innovative power-conversion topology that combines a charge pump with a buck regulator.
This converter uses a total of four switches that are used to halve a supply voltage with charge pump action. In addition, the lower two switches are used together with an inductor to convert the halved supply voltage to the desired output voltage. Figure 2 shows the circuit concept of a hybrid voltage converter. A hybrid converter is therefore the fusion of a charge pump with a downward-converting buck regulator.
The circuit from Figure 2 can be built with a hybrid controller IC, such as the LTC7821
The charge pump first reduces the input voltage, such as 48 V, by approximately half. The buck stage then converts this reduced voltage to the required output voltage.
By reducing the voltage that the buck stage has to handle, the topology can achieve higher efficiency than a conventional buck regulator, particularly when converting a relatively high intermediate voltage to a much lower output voltage.
Related Article:
- Why is converting 48 V to a low output voltage is challenging for a conventional buck regulator?
- What Are the Benefits of Using Hybrid Converters in Modern Power Systems?
- How Does the LTM4654 Achieve High-Efficiency 48 V to Low-Voltage Power Conversion?
Applicable Part Numbers
| DigiKey Part Number | Manufacturer Part Number |
|---|---|
| 505-LTC7821EUH#PBF-ND | LTC7821EUH#PBF |
| 505-LTC7821EUH#TRPBFTR-ND,505-LTC7821EUH#TRPBFCT-ND,505-LTC7821EUH#TRPBFDKR-ND | LTC7821EUH#TRPBF |
| 505-LTC7821IUH#PBF-ND | LTC7821IUH#PBF |
| LTC7821IUH#TRPBF-ND | LTC7821IUH#TRPBF |
| 505-LTM4654IY#PBF-ND | LTM4654IY#PBF |
| 505-LTM4654EY#PBF-ND | LTM4654EY#PBF |