LTC3839 Datasheet, PDF (42/50 Pages) Linear Technology – Fast, Accurate, 2-Phase, Single-Output Step-Down DC/DC Controller

LTC3839
APPLICATIONS INFORMATION
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 C_IN, 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
V_RNG setting, to improve noise immunity.
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