CDH2D09 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
MFG CO.
'CDH2D09' PDF : 44 Pages View PDF
PMIC with Integrated Charger and
Smart Power Selector for Handheld Devices
THM threshold adjustment can be accommodated by
changing RTB, connecting a resistor in series and/or in
parallel with the thermistor, or using a thermistor with dif-
ferent material constant (β). For example, a +45°C hot
threshold and 0°C cold threshold can be realized by
using a 10kΩ thermistor with a β of 4250K and connect-
ing 120kΩ in parallel. Since the thermistor resistance
near 0°C is much higher than it is near +50°C, a large
parallel resistance lowers the cold threshold, while only
slightly lowering the hot threshold. Conversely, a small
series resistance raises the cold threshold, while only
slightly raising the hot threshold. Raising RTB lowers
both the hot and cold thresholds, while lowering RTB
raises both thresholds.
PCB Layout and Routing
Good printed circuit board (PCB) layout is necessary to
achieve optimal performance. Refer to the MAX8671
evaluation kit for Maxim’s recommended layout.
Use the following guidelines for the best results:
• Use short and wide traces for high-current and dis-
continuous current paths.
• The step-down regulator power inputs are critical
discontinuous current paths that require careful
bypassing. Place the step-down regulator input
bypass capacitors as close as possible to each
switching regulator power input pair (PV_ to PG_).
• Minimize the area of the loops formed by the step-
down converters’ dynamic switching currents.
• The exposed paddle (EP) is the main path for heat
to exit the IC. Connect EP to the ground plane with
thermal vias to allow heat to dissipate from the
device.
• The MAX8671X regulator feedback nodes are sensi-
tive high-impedance nodes. Keep these nodes as
short as possible and away from the inductors.
• The thermistor node is high impedance and should
be routed with care.
• Make power ground connections to a power ground
plane. Make analog ground connections to an ana-
log ground plane. Connect the ground planes at a
single point.
TOP VIEW
8671XE
TLyww
+ aaaa
THIN QFN
5mm x 5mm x 0.8mm
Figure 15. Package Marking Example
• The REG4 LDO is a high-performance LDO with
high PSRR and low noise and care should be used
in the layout to obtain the high performance.
Generally, the REG4 LDO is powered from a step-
down regulator output, and therefore, its input
capacitor should be bypassed to the power ground
plane. However, its output capacitor should be
bypassed to the analog ground plane.
• BP is a high impedance node and leakage current
into or out of BP can affect the LDO output accuracy.
Package Marking
The top of the MAX8671X package is laser etched as
shown in Figure 15:
• “8671XETL” is the product identification code. The
full part number is MAX8671XETL; however, in this
case, the “MAX” prefix is omitted due to space
limitations.
• “yww” is a date code. “y” is the last number in the
Gregorian calendar year. “ww” is the week number
in the Gregorian calendar. For example:
“801” is the first week of 2008; the week of
January 1st, 2008
“052” is the fifty-second week of 2010; the
week of December 27th, 2010.
“aaaa” is an assembly code and lot code.
“+” denotes lead-free packaging and marks
the pin 1 location.
PROCESS: BiCMOS
Chip Information
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