3
dc2105af
DEMO MANUAL DC2105A
Quick start proceDure
Circuit Options
Detailed information is contained in the data sheet.
Optional Output Voltage:
Additional output voltages can
be programmed by selecting proper resistors for the R6
and R7 feedback network. C5 is a feed-forward capacitor
to optimize transient response and increase stability. JP1
and JP2 must be in the lower position if R6 and R7 are
used. The 10V rated output capacitors must be replaced
with suitable voltage ratings.
ISET Components:
C3, R3 and R4 are used to provide a
number of features and circuit enhancements such as,
output current limit, input current limit, optimizing out-
put ripple voltage reduction and efficiency improvement.
R4 sets maximum output current, see Figure 2 in the
LTC3630A/LTC3630 data sheet, leave open for maximum
load current. R3 and R4 can be used to set input current
limit. C3 is used to reduce output voltage ripple and op-
timize efficiency. See data sheet for details.
RUN Pin Components:
The converter is enabled when
the RUN pin voltage exceeds 1.21V and is disabled when
dropping below 0.7V. Moving JP3 to the ON position al-
lows an internal current to pull the RUN pin up to 5V. R1
and R2 are used to program input undervoltage lockout.
Select suitable resistors to divide the input voltage down
to the precision threshold voltage levels that enable and
disable the converter. Note that the maximum voltage on
the RUN pin is 6V, therefore a nominal 5V Zener diode
(D1) is required to limit the RUN pin voltage when high
input voltages are used.
20µs/DIV
0
V
IN
(V) 40
60
70
80
30
20
10
50
DC2105A F02
TWISTED WITH
10µF ALUMINUM
ELECTROLYTIC
TWISTED LEADS
V
IN
= 50V
NON-TWISTED LEADS
Figure 2. Hot Plugging Input Voltage Transient Using 12" Leads
Figure 3. Measuring Input or Output Voltage Ripple
LOAD CURRENT (A)
50
EFFICIENCY (%)
70
90
100
60
80
DC2105A F04a
1
0.001
0.0001
0.01
0.1
12V
IN
36V
IN
65V
IN
76V
IN
1.8V
OUT
LOAD CURRENT (A)
50
EFFICIENCY (%)
70
90
100
60
80
DC2105A F04b
1
0.001
0.0001
0.01
0.1
12V
IN
36V
IN
65V
IN
76V
IN
3.3V
OUT
LOAD CURRENT (A)
50
EFFICIENCY (%)
70
90
100
60
80
DC2105A F04c
1
0.001
0.0001
0.01
0.1
12V
IN
36V
IN
65V
IN
76V
IN
5V
OUT
Figure 4. Efficiency vs Load Current Curves
