DEMO MANUAL
DC2464A-A/DC2464A-B
LTC3351EUFF
Hot Swappable Supercapacitor Charger,
Backup Controller and System Monitor
DESCRIPTION
Demonstration circuit 2464A-A/2464A-B is a superca-
pacitor charger and backup controller with a hot swap-
pable front end plus supercapacitor health and system
monitoring; featuring the
LTC
®
3351.
The LTC3351
includes a buck supercapacitor charger and a backup
boost controller. It has dual input hot swap FETs to con-
trol the inrush current when connected and to discon-
nect the input supply when an over current fault or input
power loss occurs. An output ideal diode allows the
supercapacitors to supply the output when V
CAP
is above
the set backup voltage. As the capacitor stack voltage
drops down to the set output voltage, the LTC3351 will
operate as a boost regulator to supply the output until
the energy in the supercapacitors is depleted.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2464A-A/A-B
All registered trademarks and trademarks are the property of their respective owners.
TYPICAL APPLICATION
I
CHG
(STEP-DOWN)
V
IN
HS_GATE
UV
OV
OUTFET
TGATE
SW
LTC3351
BGATE
ICAP
VCAP
CAP4
CAP3
CAP2
CAP1
CAPRTN
CAPFB
V
CAP
< V
OUT
(STEP-UP)
ISNSP_HS/ ISNSM
ISNSP_CHG
OUTFB
V
CAP
> V
OUT
(DIRECT
CONNECT)
I
BACKUP
V
OUT
V
IN
2V/DIV
Example Hot Swap from 12V
V
OUT
2V/DIV
I
IN
0.2A/DIV
5ms/DIV
DC2464AAB TA01b
I
2
C
10F
10F
10F
10F
V
CAP
DC2464AAB TA01a
dc2464aabf
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DEMO MANUAL
DC2464A-A/DC2464A-B
QUICK START PROCEDURE
Obtain and connect a DC2026C board to the DC2464A
board. Use short twisted pair leads for the power connec-
tions and start with the LOAD and the power supply OFF
.
Refer to Figures 4 and 5 for the proper measurement and
equipment setup and follow the procedure below.
1. Refer to the DC2026C Quick Start Guide for
QuikEval™ setup and software installation details.
2. Make sure the USB cable is connected between the
computer and the DC2026C controller board.
3. Connect a 14-pin ribbon cable from the DC2026C
board to the DC2464A board.
4. Set jumper JP1 on the DC2464A board to the “INTV
CC
”
position.
5. Start the ADI QuikEval program. This program should
automatically detect the presence of the LTC3351
demo board (DC2464A) and activate the appropriate
GUI, as seen in Figure 9.
6. With power off, connect the appropriate supply, 0V to
20V (or 30V), 25W (or 36W) supply between the V
IN
and GND terminals for the DC2624A-A or DC2624A-B
as shown in Figure 4.
7. Turn on and set the V
IN
input power supply to 12V for
DC2624A-A or 24V for the DC2624A-B and observe the
V
IN
, V
OUT
and V
CAP
voltages and the input and charge
currents on the GUI.
NOTE. Make sure that the input voltage does not exceed
20V for the DC2624A-A or 33V for the DC2624A-B.
8. On the LTC3351 Control Window “Charger/Control”
tab, as shown in Figure 9, click on the CAP SCALE
button so it displays “SMALL”. This will provide bet-
ter time measurement resolution when measuring the
capacitance.
9. On the LTC3351 Control Window “Cap/ESR Details”
tab as shown in Figure 14, enter “2” seconds in the
“cap_i_on_settling” text box. This allows the capacitor
voltage time to reach the linear portion of the discharge
voltage slope.
10. On the LTC3351 Control Window “Cap/ESR Details”
tab as shown in Figure 14, enter “0.2” volts in the
“cap_delta_v_setting” text box and then click on the
Apply button on the bottom of the tab. This will pro-
vide a larger dV for more accuracy.
11. On the LTC3351 Control Window, click on the CAP
and ESR Measurement START button. An “In Pro-
cess” indicator displays while the measurement is
in process.
NOTE. Supercapacitors initially have large leakage
currents which causes the capacitance measure-
ment to be low. The capacitor measurements will
be more accurate after the 10F capacitors have been
continuously charged for more than 30 minutes.
12. Connect a constant power load box between V
OUT
and GND and set up to 25W for the DC2624A-A and
36W for the DC2624A-B.
13. Connect an oscilloscope probe to V
IN
, V
OUT
, V
CAP
and
PFO.
Set the oscilloscope to trigger on the fall-
ing edge of
PFO.
14. Remove the input power by unplugging the +V
IN
supply cable and observe how the output drops
to the regulation point and is maintained until the
energy in the supercapacitors is exhausted.
15. Turn the load off and set the oscilloscope to trigger
on the rising edge of V
IN
.
16. Plugin the +V
IN
supply cable and observe how V
OUT
ramps up after the debounce time, showing the
capacitors are charged up.
17. The LTC3351 has the ability to monitor and report on
the supercapacitor and system voltages, currents,
die temperature and capacitor health. See the soft-
ware section and data sheet for more information.
18. The DC2464A can be modified to operate at differ-
ent frequencies, operating voltages, input and boost
currents. The “Hardware Config” tab allows the user
to enter the appropriate changes so the GUI can
report the correct measurements. See the software
section for more details.
dc2464aabf
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Analog electronics
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