MAX26239/MAX26240

4.5V to 36V, 6A Buck-Boost Converters

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Analog Devices | 17

PCB Layout Guidelines

Careful PCB layout is critical to achieve low switching losses and clean, stable operation. Use a multilayer board whenever

possible for better noise immunity and power dissipation. Follow these guidelines for good PCB layout:

1. Place ceramic bypass capacitors close to the input and output pins to minimize high-frequency current loops. This

improves efficiency and helps minimize radiated emissions.

2. Place VCC bypass capacitors close to the IC between the VCC and AGND pins.

3. Orient the input and output capacitors to minimize the distance between their ground connections.

4. Isolate the power ground from the analog ground whenever possible. Connect the power ground to the analog ground

with a star-ground connection at the AGND pin. This keeps the ground-current loops to a minimum. In cases where

only one ground is used, adequate isolation between the analog return signals and high-power signals must be

maintained.

5. Minimize trace inductance between the LX pins and BST capacitors, placing ceramic bootstrap capacitors as close as

possible to the BST1 and BST2 pins.

6. Isolate the power components and high-current path from the sensitive analog circuitry in the compensation and

feedback loops. This is essential to prevent noise coupling into the analog signals.

7. Keep the high-current paths short, especially at the ground terminals. This practice is essential for stable, jitter-free

operation. The high-current path (composed of an input capacitor, high-side FET, inductor, and output capacitor)

should be as short as possible.

8. Keep the power traces and load connections short and wide. This practice is essential for high efficiency. Use thick

copper PCBs (2oz vs. 1oz) to enhance full-load efficiency and thermal dissipation.

9. The analog signal lines should be routed away from the high-frequency planes. This ensures the integrity of sensitive

signals feeding back into the device.

10. Place compensation components as close to the COMP pin as possible.