Rainbow Electronics MAX15046B - Manual (Page 20)

40V, High-Performance, Synchronous
Buck Controller
MAX15046
20 _____________________________________________________________________________________
PCB Layout Guidelines
Careful PCB layout is critical to achieve clean and stable
operation. The switching power stage requires particular
attention. Follow these guidelines for good PCB layout:
1) Place decoupling capacitors as close as possible to
the IC. Connect the power ground plane (connected
to PGND) and signal ground plane (connected to
GND) at one point near the device.
2) Connect input and output capacitors to the power
ground plane; connect all other capacitors to the sig-
nal ground plane.
3) Keep the high-current paths as short and wide as
possible. Keep the path of switching current (C2 to
IN and C2 to PGND) short. Avoid vias in the switching
paths.
4) Connect CSP to the drain of the low-side FET using a
Kelvin connection for accurate current-limit sensing.
5) Ensure all feedback connections are short and direct.
Place the feedback resistors as close as possible to the
IC.
6) Route high-speed switching nodes (BST, LX, DH, and
DL) away from sensitive analog areas (RT, FB, COMP,
and LIM).
24V Supply, 3.3V Output Operation
Typical Application Circuit 1 in the Typical Application
Circuits section shows an application circuit that oper-
ates out of 24V and outputs up to 10A at 3.3V. R5 sets
the switching frequency to 350kHz.
Single 4.5V to 5.5V Supply Operation
Typical Application Circuit 2 in the Typical Application
Circuits section shows an application circuit for a single
+4.5V to +5.5V power-supply operation.
Auxiliary 5V Supply Operation
Typical Application Circuit 3 in the Typical Application
Circuits section shows an application circuit for a +24V
supply to drive the external MOSFETs and an auxiliary
+5V supply to power the device