MAX1540A Datasheet, PDF (44/49 Pages) Maxim Integrated Products – Dual Step-Down Controllers with Saturation Protection, Dynamic Output, and Linear Regulator

Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
VIA TO POWER
GROUND
CONNECT THE
EXPOSED PAD TO
ANALOG GROUND
VIA TO V_CC
BYPASS CAPACITOR
MAX1540A
TOP LAYER
CONNECT GND
AND PGND TO THE
CONTROLLER AT
ONE POINT ONLY
AS SHOWN
VIA TO REF
BYPASS CAPACITOR
VIA TO V_CC PIN
MAX1540A
BOTTOM LAYER
VIA TO REF PIN
SINGLE
N-CHANNEL
MOSFETS
INDUCTOR
KELVIN-SENSE VIAS
UNDER THE SENSE RESISTOR
(REFER TO EVALUATION KIT)
INDUCTOR
C_IN
INPUT
C_OUT
C_OUT
OUTPUT
GROUND
INPUT
C_IN
C_OUT
OUTPUT
GROUND
DUAL
N-CHANNEL
MOSFET
DH
LX
DL
HIGH-POWER LAYOUT
LOW-POWER LAYOUT
Figure 19. PC Board Layout
3) Group the gate-drive components (BST_ diode and
capacitor, V_DD bypass capacitor) together near the
controller IC.
4) Make the DC-DC controller ground connections as
shown in Figures 1 and 12. This diagram can be
viewed as having two separate ground planes:
power ground, where all the high-power compo-
nents go, and an analog ground plane for sensitive
analog components. The analog ground plane and
power ground plane must meet only at a single
point directly at the IC.
5) Connect the output power planes directly to the out-
put filter capacitor positive and negative terminals
with multiple vias. Place the entire DC-DC converter
circuit as close to the load as is practical.
Chip Information
TRANSISTOR COUNT: 8612
PROCESS: BiCMOS
44 ______________________________________________________________________________________