MAX8597/MAX8598/MAX8599
Applications Information
PC Board Layout Guide
Careful PC board layout is critical to achieve low
switching losses and clean, stable operation. The
switching power stage requires particular attention.
Follow these guidelines for good PC board layout:
1) Place the high-side MOSFET close to the low-side
MOSFET and arrange them in such a way that the
drain of the high-side MOSFET and the source of
the low-side MOSFET can be tightly decoupled with
a 10µF or larger ceramic capacitor. The MOSFETs
should also be placed close to the controller IC,
preferably not more than 1.5in away from the IC.
2) Place the IC’s pin decoupling capacitors as close to
pins as possible.
3) A current-limit setting resistor must be connected from
ILIM directly to the drain of the high-side MOSFET.
4) Try to keep the LX node connection to the IC pin
separate from the connection to the flying boost
capacitor.
5) Keep the power ground plane (connected to the
source of the low-side MOSFET, PGND pin, input
and output capacitors’ ground, VL decoupling
ground) and the signal ground plane (connected to
GND pin and the rest of the circuit ground returns)
separate. Connect the two ground planes together
at the ground of the output capacitor(s).
6) Place the RC snubber circuit as close to the low-
side MOSFET as possible.
7) Keep the high-current paths as short as possible.
8) Connect the drains of the MOSFETs to a large cop-
per area to help cool the devices and further
improve efficiency and long-term reliability.
9) Ensure the feedback connection is short and direct.
Place the feedback resistors as close to the IC as
possible.
10) Route high-speed switching nodes, such as LX,
DH, and DL away from sensitive analog areas (FB,
COMP, ILIM, AIN+, AIN-).
Refer to the MAX8597/MAX8598/MAX8599 evalua-
tion kit for a sample board layout.
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
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Chip Information
TRANSISTOR COUNT: 4493
PROCESS: BiCMOS
