6 Caveats and Recommendations

Design Procedure

To design a dual-phase current shared solution, use the following steps:

1. Decide on the appropriate type of current sensing for the application
2. Calculate the component values to set a balanced current sharing op-amp circuit
3. Configure the circuits inputs following Figure 4-2
4. Follow layout guidelines as described in the Proper Symmetric PCB Layout

Proper Symmetric PCB Layout

When designing the LM62460 device it is recommended to follow layout guidelines outlined in Section 11.1 of the data sheet. Additionally the two LM62460 devices should be positioned such that the input and output PCB trace of each phase should be as symmetrical as possible. This is to achieve a proper impedance matching between the outputs of each circuit to the point of load.

Phase Shifting Circuit for Two Phase Interleaving

Without an external phase shift circuit, the main board and secondary board will still share current, but the phase of the switching between the two will not be 180 ̊ out of phase. To provide a low noise system an external phase shift circuit is advised. This can be implemented by providing an external synchronizing clock signal connected to the SYNC input main regulator. This external clock signal then needs to be phase shifted 180 ̊ through an inverter (HC04D) and connected to the SYNC input of the secondary regulator.