Linear Technology DC2133A Demo Manual page 2

DEMO MANUAL DC2133A
QUICK START PROCEDURE
Demonstration circuit 2133 is easy to set up to evaluate
the performance of LTC4079. Refer to Figure 2 for proper
measurement equipment setup and follow the procedure
below.
1. The jumpers are initially set as below for a typical 4.2V
charging application:
JP1 JP2
EN NTC
ON INT
2. With all power off, connect the input supply, battery,
and meters as shown in Figure 2.
Note: Depending on the input cable and power supply
impedance, hot plugging an input supply may cause
overvoltage transients that can damage the board. R1
and C1 form an input transient damping network that
mitigates this. See AN-88 for component selection.
3. Turn on the input power supply. Adjust the input voltage
and current limit to the desired value.
4. Monitor the PROG pin voltage for a scaled representa-
tion of the output current according to the relationship:
250 • V
PROG
I =
BAT
R
PROG
Note: Minimize capacitance on the PROG pin to prevent
charger instability.
2
JP3 JP4 JP5
TIMER VBAT LED
ON 4.2 ON
5. Allow the battery to charge for a complete cycle. CHRG
will disable the LED when the charge current has dropped
below 10mA, but the timer will continue to run and
charge current will flow until the timer period ends.
Optional
1. While powered off, change the setting of the EN jumper,
JP1, to REG to evaluate the enable input regulation
feature, or to OFF to disable charging.
2. Use an external thermistor connected to the NTC jumper,
JP2, set to EXT.
3. To terminate charge on current, disable the TIMER
input with JP3 set to OFF. LTC4079 will terminate on
C/10 only.
4. The CHRG LED can be disconnected to measure the
true quiescent current of the LTC4079 in shutdown or
for connection to external pull-up logic by setting the
LED jumper, JP5 to OFF.
5. To change the battery charging voltage, set the V
jumper, JP4. Alternatively, the feedback resistors may
be adjusted for custom values, according to the battery
voltage.
Note: DO NOT change the V
BAT
with V applied.
BAT IN
dc2133afa