MAX1981A Maxim Integrated Products, MAX1981A Datasheet - Page 39

• Manufacturer Part Number: MAX1981A
• Description: (MAX1907A / MAX1981A) Quick-PWM Master Controllers
• Manufacturer: Maxim Integrated Products

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Careful PC board layout is critical to achieve low
switching losses and clean, stable operation. The
switching power stage requires particular attention
(Figure 11). If possible, mount all of the power compo-
nents on the top side of the board with their ground ter-
minals flush against one another. Follow these
guidelines for good PC board layout:
1) Keep the high-current paths short, especially at the
Figure 11. PC Board Layout Example
Positioned CPU Core Power Supplies (IMVP-IV)
ground terminals. This is essential for stable, jitter-
free operation.
THROUGH TO ANALOG
INPUT
Quick-PWM Master Controllers for Voltage-
EXPOSED PAD TO
CONNECT THE
GROUND
ANALOG GND
MASTER CONTROLLER
______________________________________________________________________________________
PC Board Layout Guidelines
INDUCTOR
C
C
C
IN
IN
IN
MAX1907A/MAX1981A
(MASTER)
POWER GROUND
(2nd LAYER)
C
C
C
C
OUT
OUT
OUT
OUT
THROUGH TO POWER
(2nd LAYER)
GROUND
GROUND
POWER
UNDER-THE-SENSE RESISTOR
(REFER TO EVALUATION KIT)
KELVIN SENSE THROUGH
POWER GROUND
OUTPUT
CPU
ONE POINT ONLY
CONTROLLER AT
< 10Ω
AND PGND THE
CONNECT GND
2) Connect all analog grounds to a separate solid cop-
3) The master controller should also have a separate
AS SHOWN
per plane, which connects to the GND pin of the
MAX1907A/MAX1981A. This includes the V
bypass capacitor, REF bypass capacitor, compen-
sation (CC) capacitor, and the resistive-dividers
connected to ILIM and POS/NEG.
analog ground. Return the appropriate noise sensi-
tive components to this plane. Since the reference
in the master is sometimes connected to the slave,
it may be necessary to couple the analog ground in
MAX1980
(SLAVE)
C
C
C
C
OUT
OUT
OUT
OUT
THROUGH TO POWER
SLAVE CONTROLLER
GROUND
CONNECT THE
EXPOSED PAD TO
ANALOG GND
INDUCTOR
C
C
C
IN
IN
IN
INPUT
CC
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