LTC3880 datasheet(42/50 Pages) LINER

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LTC3839

3839fa

The capacitor placed across the current sensing pins needs

to be placed immediately adjacent to the pins of the IC.

This capacitor helps to minimize the effects of differential

noise injection due to high frequency capacitive coupling.

If problems are encountered with high current output

loading at lower input voltages, look for inductive coupling

between CIN, top and bottom MOSFET components to the

sensitive current and voltage sensing traces.

In addition, investigate common ground path voltage pickup

between these components and the SGND pin of the IC.

High Switching Frequency Operation

At high switching frequencies there may be an increased

sensitivity to noise. Special care may need to be taken to

prevent cycle-by-cycle instability and/or phase-lock jitter.

First, carefully follow the recommended layout techniques

to reduce coupling from the high switching voltage/current

traces. Additionally, use low ESR and low impedance X5R

or X7R ceramic input capacitors: up to 5μF per Ampere of

load current may be needed. If necessary, increase ripple

sense voltage by increasing sense resistance value and

VRNG setting, to improve noise immunity.

APPLICATIONS INFORMATION

LTC3880 Datasheet(PDF) 42 Page - Linear Technology