Rainbow Electronics MAX8982X - Manual (Page 71)

Power-Management ICs for
ICERA E400/E450 Platform
MAX8982A/MAX8982X
71
Output Capacitor Selection
The output capacitor, C OUT , is required to keep the
output voltage ripple small and to ensure regulation loop
stability. C
OUT must have low impedance at the switch-
ing frequency. Ceramic capacitors with X5R or X7R tem-
perature characteristics are highly recommended due to
their small size, low ESR, and small temperature coef-
ficients. Due to the unique feedback network, the output
capacitance can be very low. Recommended capacitor
values are shown in Figures 1 and 2.
Input Capacitor Selection
The input capacitor, C IN1_ or C IN_ , reduces the current
peaks drawn from the input power source and reduces
switching noise in the IC. The impedance of C
IN2 at the
switching frequency should be kept very low. Ceramic
capacitors with X5R or X7R temperature characteristics
are highly recommended due to their small size, low
ESR, and small temperature coefficients. Recommended
capacitor values are shown in Figures 1 and 2.
PCB Layout Guidelines
Due to fast switching waveforms and high current paths,
careful PCB layout is required to achieve optimal perfor-
mance. Minimize trace lengths between the IC and the
inductor, the input capacitor, and the output capacitor
for each step-down converter. Keep these traces short,
direct, and wide. Route noise sensitive traces away from
the switching nodes (LX_).
Refer to the MAX8982A/MAX8982X EV Kit for a PCB
layout example.
Chip Information
PROCESS: BiCMOS