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dc2133afa

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

JP3

JP4

JP5

EN

NTC

TIMER

VBAT

LED

ON

INT

ON

4.2

ON

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:

Note: Minimize capacitance on the PROG pin to prevent

charger instability.

5. Allow the battery to charge for a complete cycle. CHRG

willdisabletheLEDwhenthechargecurrenthasdropped

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. UseanexternalthermistorconnectedtotheNTCjumper,

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.

jumper, JP4. Alternatively, the feedback resistors may

be adjusted for custom values, according to the battery

voltage.