MAX1535 Maxim Integrated Products, MAX1535 Datasheet - Page 37

• Manufacturer Part Number: MAX1535
• Description: Highly Integrated Level 2 Smbus Battery Charger
• Manufacturer: Maxim Integrated Products

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Use the following step-by-step guide:
1) Place the high-power connections first, with their
• Minimize the current-sense resistor trace lengths,
• Minimize ground trace lengths in the high-current
• Minimize other trace lengths in the high-current
• Use >5mm wide traces in the high-current paths.
• Connect C1 and C2 to the high-side MOSFET
• Minimize the LX node (MOSFETs, rectifier cathode,
grounds adjacent:
and ensure accurate current sensing with Kelvin
connections.
paths.
paths.
(10mm, max length).
inductor (15mm, max length)).
Ideally, surface-mount power components are flush
against each other with their ground terminals
almost touching. These high-current grounds are
then connected to each other with a wide, filled
zone of top-layer copper, so they do not go through
vias. The resulting top-layer subground plane is con-
nected to the normal inner-layer ground plane at the
output ground terminals, which ensures that the IC’s
analog ground is sensing at the supply’s output ter-
minals without interference from IR drops and
ground noise. Other high-current paths should also
be minimized, but focusing primarily on short
ground and current-sense connections eliminates
about 90% of all PC board layout problems.
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Highly Integrated Level 2 SMBus
2) Place the IC and signal components. Keep the main
3) Keep the gate drive traces (DHI and DLO) as short
4) Place ceramic bypass capacitors close to the IC.
5) Use a single-point star ground placed directly below
TRANSISTOR COUNT: 11,900
PROCESS: BiCMOS
switching node (LX node) away from sensitive analog
components (current-sense traces and the REF
capacitor). Important: The IC must be no further than
10mm from the current-sense resistors. Quiet con-
nections to REF, VMAX, IMAX, CCV, CCI, CCS, ACIN,
and DCIN should be returned to a separate ground
(GND) island. The appropriate traces are marked on
the schematic with the ground symbol
very little current flowing in these traces, so the
ground island need not be very large. When placed
on an inner layer, a sizable ground island can help
simplify the layout because the low-current connec-
tions can be made through vias. The ground pad on
the backside of the package should also be con-
nected to this quiet ground island.
as possible (L < 20mm), and route them away from
the current-sense lines and REF. These traces
should also be relatively wide (W > 1.25mm).
The bulk capacitors can be placed further away.
Place the current-sense input filter capacitors under
the part, connected directly to the GND pin.
the part at the PGND pin. Connect the power ground
(ground plane) and the quiet ground island at this
location. See Figure 18 for a layout example.
Battery Charger
Chip Information
( )
. There is
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