LM2830, LM2830-Q1

SNVS454E – AUGUST 2006 – REVISED DECEMBER 2014

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9 Power Supply Recommendations

The LM2830 is designed to operate from an input voltage supply range between 3.0 V and 5.5 V. This input

supply should be able to withstand the maximum input current and maintain a voltage above 3.0 V. If the input

supply is located farther away (more than a few inches) from the LM2830, additional bulk capacitance may be

required in addition to the ceramic bypass capacitors.

10 Layout

10.1 Layout Guidelines

When planning layout there are a few things to consider when trying to achieve a clean, regulated output. The

most important consideration is the close coupling of the GND connections of the input capacitor and the catch

diode D1. These ground ends should be close to one another and be connected to the GND plane with at least

two through-holes. Place these components as close to the IC as possible. Next in importance is the location of

the GND connection of the output capacitor, which should be near the GND connections of CIN and D1.

There should be a continuous ground plane on the bottom layer of a two-layer board except under the switching

node island.

The FB pin is a high-impedance node and care should be taken to make the FB trace short to avoid noise pickup

and inaccurate regulation. The feedback resistors should be placed as close as possible to the IC, with the GND

of R1 placed as close as possible to the GND of the IC. The VOUT trace to R2 should be routed away from the

inductor and any other traces that are switching.

High AC currents flow through the VIN, SW and VOUT traces, so they should be as short and wide as possible.

However, making the traces wide increases radiated noise, so the designer must make this trade-off. Radiated

noise can be decreased by choosing a shielded inductor.

The remaining components should also be placed as close as possible to the IC. See Application Note AN-1229

SNVA054 for further considerations and the LM2830 demo board as an example of a four-layer layout.

10.2 Layout Example

Figure 29. Example Schematic

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