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
DC
VDCL
4.0V RISING (TYP)
500mV HYST
VDCH
6.9V RISING (TYP)
400mV HYST
MAX8671X
USB
UNDERVOLTAGE
DOK
USB
OVERVOLTAGE
AGND
Figure 5. DC Power-OK Logic
Battery Charger
Figure 6 shows the typical Li+/Li-Poly charge profile for
the MAX8671X, and Figure 7 shows the battery charger
state diagram.
With a valid DC and/or USB input, the battery charger
initiates a charge cycle when the charger is enabled. It
first detects the battery voltage. If the battery voltage is
less than the prequalification threshold (3.0V), the
charger enters prequalification mode in which the bat-
tery charges at 10% of the maximum fast-charge cur-
rent while deeply discharged. Once the battery voltage
rises to 3.0V, the charger transitions to fast-charge
mode and applies the maximum charge current. As
charging continues, the battery voltage rises until it
approaches the battery regulation voltage (selected
with BVSET) where charge current starts tapering
down. When charge current decreases to 4% of the
maximum fast-charge current, the charger enters a
brief 15s top-off state and then charging stops. If the
battery voltage subsequently drops below the battery
regulation voltage by VBATRCHG, charging restarts and
the timers reset.
The battery charge rate is set by several factors:
• Battery voltage
• USB/DC input current limit
• Charge setting resistor, RCISET
• System load (ISYS)
• Die temperature
The MAX8671X automatically reduces charge current
to prevent input overload. MAX8671X also reduces
charge current when in thermal regulation (see the
Thermal Limiting and Overload Protection section for
more information).
Battery Regulation Voltage (BVSET)
BVSET allows the maximum battery charge voltage to
be set to 4.1V, 4.2V, or 4.350V. Drive BVSET low to set
the regulation voltage to 4.1V. Connect BVSET to VL or
leave unconnected to set the regulation voltage to 4.2V.
Connect BVSET to AGND through a 45kΩ to 55kΩ
resistor (RBVSET) to set the regulation voltage to
4.350V. RBVSET accuracy is not critical. A 51kΩ ±5%
resistor is acceptable.
Charge Enable Input (CEN)
CEN is a digital input. Driving CEN high disables the
battery charger. CEN does not affect the USB or DC
current limit. Driving USUS high also disables the bat-
tery charger when charging from a USB source (PEN1
= low).
In many systems, there is no need for the system
controller (typically a microprocessor (µP)) to disable
the charger because the MAX8671X independently
manages the charger power path. In these situations,
CEN can be connected to ground. Do not leave
CEN unconnected.
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