Linear Technology 1376A-A, Быстрый старт, Страница: 2 / 7

LTC3555-1 AND LTC3555-3
2
Complete the Quick Start Procedure outlined in the
Quick Start Guide for Demo Circuit 590 available from
the Linear Technology Web Site, prior to proceeding.
Refer to Figure 2 for proper measurement equipment
setup and follow the procedure below:
NOTE. When measuring the input or output voltage ripple, care must be
taken to avoid a long ground lead on the oscilloscope probe. Measure the
input or output voltage ripple by touching the probe tip directly across the
VBUS or VOUT(x) and GND terminals. See
Figure 3 for proper scope probe
technique.
1. After following the software installation procedure
in the DC590 Quick Start Guide, connect the
DC1376A, the DC590 and the Host PC as shown in
Figure 2.
NOTE. If using the DC590B board, a specific DVCC voltage level may be
selected. This is done by setting the VCCIO jumper on the DC590
board to one of the following settings: 3.3V, 5V, removed for 2.7V or
set to external if an external supply is desired to be used.
2. Run the QuikEval.exe software. The QuikEval soft-
ware detects the DC1376A-A or the DC1376A-B
demo board and the LTC3555 Graphical User Inter-
face (GUI), shown in
Figure 1, will pop-up.
Figure 1. Graphical User Interface Demonstration Software for
DC1376A-A and DC1376A-B.
3. If using an external supply, connect a 0 to 6V, 1.5A
supply with voltage adjusted to 0V between the
VBUS and GND terminals. Connect a voltmeter
across the VBUS and GND terminals. If using the
USB input option, plug in the USB cable after all
loads and jumpers are set. Connect the positive ter-
minal of a voltmeter to CLPROG and the negative
terminal to GND to measure the average input cur-
rent. The voltage on CLPROG will reach 1.188V when
the average input current limit is reached.
Do not
use the USB input and an external supply at the
same time
.
4. Set JP1, (NTC) to “INT” to use the demo board re-
sistor network. To use an external NTC resistor, con-
nect the external NTC resistor between the J2-3 ter-
minal and the GND terminal. Then set the NTC
jumper to “EXT”.
5. Set JP2 and JP3 (ILIM0 and ILIM1 respectively) to
“LO”. At Power-up, the average input current setting
will be equal to the value set by the position of JP2
and JP3 until an I
2
C command is received and over-
writes that default value.
TABLE 1. Input Current Limit Settings
ILIM1 ILIM0 CURRENT LIMIT
0 0 100mA (1X)
0 1 1A (10X)
1 0 0.5mA (SUSP)
1 1 500mA (5X)
6. Connect a 0 to 25mA adjustable load in series with
an ammeter between the LDO3V3 and GND termi-
nals. Connect a voltmeter between the LDO3V3 and
GND terminals.
7. Connect a 0 to 2A adjustable load in series with an
ammeter between the VOUT terminal and the GND
terminal. Connect a voltmeter between the VOUT and
GND terminals.
8. Connect a 0 to 400mA adjustable load in series with
an ammeter between the VOUT1 and GND terminals.
Connect a voltmeter between the VOUT1 and GND
terminals.
9. Connect a 0 to 400mA adjustable load in series with
an ammeter between the VOUT2 and GND terminals.
Connect a voltmeter between the VOUT2 and GND
terminals.