MAX1501 Maxim Integrated Products, MAX1501 Datasheet - Page 10

• Manufacturer Part Number: MAX1501
• Description: Highly Integrated Linear Battery Charger with Thermal Regulation for Portable Applications
• Manufacturer: Maxim Integrated Products

Connect CHGEN and MODE to GND to place the
MAX1501 in Li+ charging mode. The Li+ charger con-
sists of a voltage-control loop, a current-control loop,
and a thermal-control loop. Connect SELV to GND to
set the Li+ battery voltage to 4.1V. Connect SELV to VL
to set the Li+ battery voltage to 4.2V (Table 2).
The MAX1501 precharges the Li+ battery with 10% of
the user-programmed fast-charge current at the start of
a charge cycle. A soft-start algorithm ramps up the
charging current (10% steps with 20ms duration per
step) to the fast-charge current when the battery volt-
age reaches 2.8V. The MAX1501 enters constant-volt-
age mode and decreases the charge current when the
BATT voltage reaches the selected regulation voltage
(4.1V or 4.2V). Set the fast-charge current with a resis-
tor between SETI and GND (see the Charge-Current
Selection section).
Highly Integrated, Linear Battery Charger with
Thermal Regulation for Portable Applications
Table 2. Battery Regulation Voltage
Figure 3. Li+ Charge Sequence
10
Li+
NiMH/NiCd
10% OF FAST-CHARGE CURRENT
______________________________________________________________________________________
CHARGING MODE
MINIMUM CHARGE VOLTAGE
FAST-CHARGE CURRENT
REGULATION VOLTAGE
(2.8V)
PREQUALIFICATION
t
PREQUAL
GND
4.1V
4.5V
Li+ Charge Mode
SELV
4.95V
4.2V
VL
FAST CHARGING
t
MAX
BATTERY
VOLTAGE
The thermal-regulation loop limits the MAX1501 die
temperature to the value selected by the TEMP input by
reducing the charge current as necessary (see the
Thermal-Regulation Selection section). This feature not
only protects the MAX1501 from overheating, but also
allows the charge current to be set higher without
risking damage to the system.
Set the top-off-current threshold with the three-state
FULLI input (see the Top-Off-Current Selection section).
RLED goes high impedance and GLED asserts low when
the top-off-current threshold is reached. The MAX1501
automatically initiates recharging when the battery volt-
age drops below 95% of the voltage set by SELV.
Connect CHGEN to GND and MODE to VL to place the
MAX1501 in NiMH/NiCd charging mode. The
NiMH/NiCd battery charger consists of a current-con-
trol loop, a voltage-control loop, and a thermal-control
loop. Connect SELV to GND to set the regulation volt-
age to 4.5V. Connect SELV to VL to set the regulation
voltage to 4.95V (Table 2). When charging three
NiMH/NiCd cells to 4.95V, V
and a µP must be used to terminate the charge
sequence.
CURRENT
BATTERY
RLED TURNS OFF AND GLED
TURNS ON WHEN CHARGE CURRENT
DROPS TO VALUE SET BY FULLI
(10%, 20%, OR 30% OF FAST-
CHARGE CURRENT).
NiMH/NiCd Charge Mode
TOP-OFF
IN
must be at least 5.25V
TERMINATED
CHARGE
DONE