MAX15005 Maxim Integrated Products, MAX15005 Datasheet - Page 23

• Manufacturer Part Number: MAX15005
• Description: (MAX15004 / MAX15005) 4.5V to 40V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
• Manufacturer: Maxim Integrated Products

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Typically, there are two sources of noise emission in a
switching power supply: high di/dt loops and high dv/dt
surfaces. For example, traces that carry the drain cur-
rent often form high di/dt loops. Similarly, the heatsink
of the MOSFET connected to the device drain presents
a dv/dt source; therefore, minimize the surface area of
the heatsink as much as possible. Keep all PCB traces
carrying switching currents as short as possible to mini-
mize current loops. Use a ground plane for best results.
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. Refer to the
MAX15005 EV kit data sheet for a specific layout exam-
ple. Use a multilayer board whenever possible for bet-
ter noise immunity. Follow these guidelines for good
PCB layout:
1) Use a large copper plane under the package and
2) Do not connect the connection from SGND (pin 7)
Flyback/Boost/SEPIC Power-Supply Controllers
solder it to the exposed pad. To effectively use this
copper area as a heat exchanger between the PCB
and ambient, expose this copper area on the top
and bottom side of the PCB.
to the EP copper plane underneath the IC. Use mid-
layer-1 as an SGND plane when using a multilayer
board.
______________________________________________________________________________________
Layout Recommendations
4.5V to 40V Input Automotive
3) Isolate the power components and high-current
4) Keep the high-current paths short, especially at the
5) Connect SGND and PGND together close to the
6) Keep the power traces and load connections short.
7) Ensure that the feedback connection to FB is short
8) Route high-speed switching nodes away from the
9) Connect SYNC pin to SGND when not used.
path from the sensitive analog circuitry.
ground terminals. This practice is essential for sta-
ble, jitter-free operation.
device at the return terminal of V
tor. Do not connect them together anywhere else.
This practice is essential for high efficiency. Use
thick copper PCBs (2oz vs. 1oz) to enhance full-
load efficiency.
and direct.
sensitive analog areas. Use an internal PCB layer
for SGND as an EMI shield to keep radiated noise
away from the device, feedback dividers, and ana-
log bypass capacitors.
CC
bypass capaci-
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