MAX1909ETI Maxim Integrated Products, MAX1909ETI Datasheet - Page 29

• Manufacturer Part Number: MAX1909ETI
• Description: Battery Management
• Manufacturer: Maxim Integrated Products

Specifications of MAX1909ETI

• Product: Charge Management
• Battery Type: Li-Ion, Li-Polymer, NiCd, NiMH, Lead Acid, Universal
• Operating Supply Voltage: 8 V to 28 V
• Supply Current: 2.7 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Package / Case: TQFN-28
• Charge Safety Timers: No
• Mounting Style: SMD/SMT
• Temperature Monitoring: No
• Uvlo Start Threshold: 9.18 V
• Uvlo Stop Threshold: 9.42 V
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

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
Multichemistry Battery Chargers with Automatic
e) Connect C1 and C2 to the high-side MOSFET
f)
switching node (LX node) away from sensitive ana-
log components (current-sense traces and REF
capacitor). Important: the IC should be less than
10mm from the current-sense resistors.
Quiet connections to REF, VCTL, ICTL, CCV, CCI,
CCS, IINP, ACIN, and DCIN should be returned to a
separate ground (GND) island. The appropriate
traces are marked on the schematic with the
ground symbol (
ing in these traces, so the ground island need not
be very large. When placed on an inner layer, a siz-
able ground island can help simplify the layout
because the low-current connections can be made
through vias. The ground pad on the backside of
the package should also be connected 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.
below the part at the PGND pin. Connect the power
ground (ground plane) and the quiet ground island
at this location. See Figure 12.
(10mm max length). Return these capacitors to
the power ground plane.
Minimize the LX node (MOSFETs, rectifier cath-
ode, inductor (15mm max length)).
Ideally, surface-mount power components are
flush against one another 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 ground plane is connected
to the normal inner-layer ground plane at the out-
put ground terminals, which ensures that the IC’s
analog ground is sensing at the supply’s output
terminals 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.
______________________________________________________________________________________
). There is very little current flow-
System Power Selector
TRANSISTOR COUNT: 2720
PROCESS: BiCMOS
Figure 12. PC Board Layout Examples
INPUT
INDUCTOR
QUIET GROUND
C
IN
ISLAND
Chip Information
POWER PATH
C
C
PGND
OUT
OUT
GND
OUTPUT
(REFER TO EVALUATION KIT)
KELVIN-SENSE VIAS
UNDER THE SENSE
RESISTOR
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