Evaluates: MAX1737
MAX1737 Evaluation Kit
2 _______________________________________________________________________________________
Quick Start
The MAX1737 EV kit is a fully assembled and tested
surface-mount board. Follow the steps below to verify
board operation. Do not turn on the power supply
until all connections are completed. Observe all pre-
cautions on the battery manufacturer’s data sheet.
Use only lithium-ion cells with this charger:
1) Set jumper JU6 to indicate the number of cells in
the battery pack (Table 1).
2) Place a shunt on jumper JU1 to disable the temper-
ature monitoring function.
3) Place a shunt across pins 1-2 on JU2 to enable the
MAX1737.
4) Place a shunt across JU3 to enable 2A charging
current limit.
5) Place a shunt across JU4 to enable 2A input current
limit.
6) Remove any shunt from JU5 to set the cell voltage
to 4.2V. If a different battery regulation voltage is
required, refer to the MAX1737 data sheet.
7) Connect a +7VDC to +28VDC power supply with
sufficient power rating across the VIN and GND
pads.
8) Connect a lithium-ion battery pack between the
BATT+ and BATT- pads.
9) Turn on the power supply.
10) Measure the battery voltage and verify that the
LEDs indicate the correct state.
Detailed Description
When battery charging is initiated, the charger enters
the prequalification state. In this state, the batteries are
charged at 1/20 of the programmed current limit while
the charger measures the battery to determine if it can
be charged. If the battery voltage is above 2.5V per
cell, charging begins. At this time, the batteries are
charged at a constant current (Fast Charge state) and
a constant voltage (Full Charge state). The charger
exits the Full Charge state and enters the Top Off state
once the battery current drops to 10% of the Fast
Charge current, or the Fast Charge timer expires. The
charger remains in the Top Off state for 45 minutes, at
which time charging is terminated.
Once charging is terminated, if the battery voltage
drops 5% from the fully charged voltage, charging
automatically restarts.
If, at any time during charging, the thermistor input sens-
es a temperature below 0°C or above +50°C, charging
suspends until the temperature returns to a safe level. If
the charger is unable to enter the Fast Charge or Full
Charge state, charging is terminated and the Fault LED
(red) lights indicate a faulty battery. This kit is shipped
with a 10kΩ resistor to disable the temperature monitor-
ing function. If temperature monitoring is required, con-
nect the appropriate thermistor (see Jumper Selection
section).
For more information on the operation of the MAX1737,
refer to the Detailed Description section of the
MAX1737 data sheet.
Charging Status
The three LEDs on the EV kit indicate the charging status:
• LED1 (FULLCHG) indicates that the battery pack is
being charged with a constant voltage.
• LED2 (FASTCHG) indicates that the battery pack is
being charged with a constant current.
• LED3 (FAULT) indicates that charging terminated
abnormally.
Jumper Selection
Jumper JU1 connects the MAX1737 thermistor input
(THERM) to GND through a 10kΩ resistor, disabling
temperature qualification. To enable temperature quali-
fication (charging between 0°C and 50°C), remove the
shunt from JU1, and connect a thermistor (BC Compo-
nents part number 2322-640-63103 or equivalent) to
the THERM and GND pads. For more information, refer
to the MAX1737 data sheet.
The MAX1737 can be placed in shutdown mode using
jumper JU2. See Table 1 for jumper settings.
Jumper JU3 sets the charging current limit (current to
the battery). A shunt across this jumper limits the output
current to 2A. With the shunt removed, a resistor-divider
formed by R5 and R6 sets the current. The EV kit
comes with the resistors selected for a 1A current limit.
A different current can be selected by changing the
resistors (refer to the MAX1737 data sheet).
Jumper JU4 sets the input current limit (current from the
power supply). A shunt across this jumper limits the
input current to 2A. With the shunt removed, a resistor-
divider formed by R7 and R8 sets the current. The EV
kit comes with the resistors selected for a 1A current
limit. A different current can be selected by changing
the resistors (refer to the MAX1737 data sheet).
Jumper JU5 sets the voltage per cell. Jumper JU6
selects the number of series cells to be charged. See
Table 1 for jumper settings.
