2

dc2118af

DEMO MANUAL DC2118A

QUICK START PROCEDURE

Demonstration circuit 2118A is easy to set up to evaluate

the performance of LTC4040. Refer to Figure 2 for proper

measurement equipment setup and follow the procedure

below.

1. The jumpers are set as below for a typical 4.1V charg-

ing application:

JP1

NTC

INT

JP2

ENCHG

ON

JP3

ENBST

ON

JP4

F1

1

JP5

F0

1

JP6

LEDS

ON

JP7

F2

1

2. With all power off, connect the input supply, system

load, and meters as shown in Figure 3.

Charge Mode

3. Connect the battery as shown in Figure 3 to charge at

4.1V, 2A. For alternate charge voltage settings, refer

to Table 1.

4. Turn on the input power supply to evaluate charge

mode. Adjust the input voltage and current limit to

the desired value.

NOTE: While DC2118A is robust to overvoltage condi-

tions up to 40V on DCIN, DO NOT exceed this limit or

damage may occur to MOSFET Q1 and IC U1.

5. Turn on and adjust the system load as necessary.

Charging current will be limited when input current

exceeds 2.5A.

6. The CHRG LED will toggle off when the charge current

has dropped below 250mA. The timer will continue to

run and charging will continue until the timer period

ends. Multiple timer periods may be necessary to fully

charge a large capacity battery, such as the one used

to obtain Figure 1.

7. If the battery voltage does not increase above the low

battery threshold during the precondition time or the

thermistor value exceeds the normal range, CHRG will

toggle off and FAULT will toggle on indicating a bad

battery.

Backup Mode

8. Turn off the input power supply to evaluate backup

mode.

9. The PFO LED will toggle on indicating input power

failure.

10. Adjust the system load as necessary.

Figure 1. Typical Battery Charge Cycle

Figure 2. Typical Battery Discharge Cycle

PERFORMANCE SUMMARY

TIME (Hrs)

0

2.25

2.00

1.50

1.00

0.50

1.75

1.25

0.75

0.25

0

4.2

4.0

3.6

3.2

2.8

3.8

3.4

3.0

2.6

2.4

5

9

3

7

dc2118 F01

10

4

8

2

6

1

9600mAh Li-Ion

RPROG = 1.00k

TIMER

RESTART

TIMER

START

CHRG

C/8

TERMINATION

TIME (Hrs)

0:00

5

4

2

3

1

0

5

4

2

3

1

0

1:30

dc2118a F02

2:30

2:00

1:00

0:30

9600mAh Li-Ion

POWER

FAIL

BACKUP

STARTED