LM2733

SNVS209F – NOVEMBER 2002 – REVISED DECEMBER 2014

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9 Power Supply Recommendations

The device input voltage range is 2.7 V to 14 V.

The voltage on the shutdown pin should not exceed the voltage on the VIN pin. For applications that do not

require a shutdown function the shutdown pin may be connected to the VIN pin. In this case a 47-K

Ω resistor is

recommended to be connected between these pins.

10 Layout

10.1 Layout Guidelines

High frequency switching regulators require very careful layout of components in order to get stable operation

and low noise. All components must be as close as possible to the LM2733 device. It is recommended that a 4-

layer PCB be used so that internal ground planes are available.

Some additional guidelines to be observed:

1. Keep the path between L1, D1, and C2 extremely short. Parasitic trace inductance in series with D1 and C2

will increase noise and ringing.

2. The feedback components R1, R2 and CF must be kept close to the FB pin of U1 to prevent noise injection

on the FB pin trace.

3. If internal ground planes are available (recommended) use vias to connect directly to ground at pin 2 of U1,

as well as the negative sides of capacitors C1 and C2.

10.2 Layout Example

Figure 34. Recommended PCB Component Layout

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