Typical Application; Quick Start Procedure - Linear Technology DC1937B Demo Manual

DEMO MANUAL DC1937B

TYPICAL APPLICATION

High Current Supercapacitor Charger and Backup Supply
I (STEP-DOWN)
CHG
V
IN
INFET VOUTSP VOUTSN
PFI
LTC3350
2
I C

QUICK START PROCEDURE

Obtain and connect a DC590B board to the DC1937B board.
Using short twisted pair leads for the power connections
and with the LOAD and the power supply OFF. Refer to
Figure 1 and Figure 2 for the proper measurement and
equipment setup. Follow the procedure below.
1. Refer to the DC590B Quick Start Guide for QuikEval™
setup and software installation details.
2. Make sure the USB cable is connected between the
computer and the DC590B controller board.
3. Connect a 14-pin ribbon cable from the DC590B board
to the DC1937B board.
4. Set the VCCIO jumper, JP6, on the DC590B board to
the 5V position.
5. Set the JP1 jumper on the DC1937B board to the
DC590 position.
6. Start the Linear Technology QuikEval program. This
program should automatically detect the presence of
the LTC3350 demo board (DC1937B) and activate the
appropriate GUI, as seen in Figure 5.
2
I
BACKUP
OUTFB
OUTFET
V < V
CAP OUT
(STEP-UP)
TGATE
SW
BGATE
ICAP
VCAP
CAP4
10F
CAP3
10F
CAP2
10F
CAP1
10F
CAPRTN
CAPFB
V
OUT
V > V
CAP OUT V
OUT
(DIRECT
2V/DIV
CONNECT)
V
CAP
2V/DIV
V
IN
2V/DIV
0V
V
CAP
BACK PAGE APPLICATION CIRCUIT
dc1937b TA01a
7. With power off, connect a 0V to 20V, 25W supply
between the VIN and GND terminals with a series
ammeter and a voltmeter as shown in Figure 1.
8. Turn on and set the VIN input power supply to 12V and
observe the CAP voltages, input and charge current
on the GUI.
NOTE. Make sure that the input voltage does not
exceed 20V.
NOTE. The LTC3350 is intended to operate with a low
impedance source. If operating near the PFI rising
threshold, make sure the input voltage does not drop
more than 30mV • (R5 + R6)/R6, 266mV, during a
charge event.
9. On the LTC3350 Control Window, click on the CAP
and ESR Measurement START button. An In Process
indicator displays while the measurement is in process.
NOTE. Supercapacitors initially have large leakage
currents which causes the capacitance measurement
to be low. The capacitor measurements will be more
accurate after the 10F capacitors have been continu-
ously charged for more than 30 minutes.
Backup Operation
P = 25W
BACKUP
V
OUT
V
CAP
V
IN
400ms/DIV
dc1937b TA01b
dc1937bf