2

dc1977afb

DEMO MANUAL

DC1977A-A/DC1977A-B

assemBly test proceDure

Refer to Figure 1 for the proper measurement equipment

setup and jumper settings and follow the procedure below.

1. Set JP1 (“MPPT”) to ‘ON’, set PS1 to 3.6V and turn

on.

2. Connect PS2 to point A, set to 15V and turn on.

3. Verify that VM1 indicates 3.3V to 3.9V, and then verify

that AM1 indicates 387mA to 417mA. Verify that VM2

shows 14.5V to 15.1V. There is only a series diode

purpose of this diode is prevent backfeeding a PV

activate the MPPT feature, and the LTC4121 delivers

full charge current to the battery.

4. Turn PS2 off, move connection to point B, and turn

PS2 on.

5. Verify that VM1 indicates 3.3V to 3.9V, and then verify

that AM1 indicates 387mA to 417mA. Verify that VM2

shows 12.6V to 13.2. The source impedance of the

power supply is now ≈ 16Ω. But this impedance still

allows delivering full charge current without engaging

the MPPT feature.

6. Turn PS2 off, move connection to Point C, and turn

PS2 on.

7. Verify that VM1 indicates 3.3V to 3.9V, and then Verify

that AM1 indicates 105mA to 115mA. Verify that VM2

shows 10.6V to 11.3V. The source impedance of the

power supply is now 98Ω. The MPPT feature has

engaged and the charge delivered to the battery has

MPPT point.

8. Set JP1 (“MPPT”) to ‘OFF’, test is finished.

+

–

+

–

B

C

PS2

15V POWER SUPPLY

0.25A

+

–

PS1

3.6V BIPOLAR SUPPLY

1A

+

–

–

+

–

AM1

3.6

VM1

VM2

15.8

2W

82.4

2W

AM2

A

DC1977a F03

Figure 1. DC1977A Equipment Setup

Note: All connections from equipment should be kelvin-connected directly to the board pins

which they are connected on this diagram. All input or output leads should be twisted pair.