DC2105A-A

1
dc2105af
DEMO MANUAL DC2105A
Description
LTC3630AEMSE/LTC3630EMSE
High Efficiency High Voltage 500mA
Synchronous Step-Down Converter
Demonstration circuit 2105A is a 500mA output DC/DC
power supply. There are two versions: DC2105A-A is a
board featuring LTC
®
3630A, with 4V to 76V input range;
DC2105A-B is a board featuring LTC3630, with 4V to 65V
input range. The LTC3630A/LTC3630 operates in a high
efficiency Burst Mode
®
operation and includes internal
high and low side switches. The board provides jumper
selected output voltages of 1.8V, 3.3V, 5V and an option
for additional voltages. LTC3630A/LTC3630 has internal
soft-start and a provision for increasing soft-start time.
Included on the board is an ON/OFF jumper that can also
be configured as a precision undervoltage lockout. Ad
-
ditional PC pads are included for programming current
limit
to optimize efficiency and for reducing output voltage
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
performance summary
ripple and reducing component size. A terminal (FBO)
is available to allow multiple boards to be paralleled for
increasing output current.
Output voltage between 800mV and V
IN
can be pro-
grammed using optional resistors, although higher voltage
output capacitors will be required.
The LTC3630A/LTC3630 data sheet gives a complete de-
scription of the operation and application information.
The data sheet must be read in conjunction with this
demo manual.
Design files for this circuit board are available at
http://www.
linear.com/demo/DC2105A
Specifications are at T
A
= 25°C
PARAMETER CONDITION VALUE
Input Voltage Range for DC2105A-A LTC3630A 4V to 76V
Input Voltage Range for DC2105A-B LTC3630 4V to 65V
1.8V Output V
IN
= 20V, V
OUT
Load = 100mA 1.8V ±2%
3.3V Output V
IN
= 20V, V
OUT
Load = 100mA 3.3 V ±2%
5V Output V
IN
= 20V, V
OUT
Load = 100mA 5V ±2%
Maximum Output Current V
IN
= 20V, V
OUT
= 5V 500mA
Typical Output Voltage Ripple V
IN
= 20V, V
OUT
= 5V 75mV
P-P
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dc2105af
DEMO MANUAL DC2105A
Quick start proceDure
This DC2105A can be evaluated using the setup shown
in Figure 1.
1. Connect the DVMs to the input and output. Select 5V
setting using jumper JP1 (lower position) and JP2
(upper position), select ON position for JP3.
2. With input power supply set for 0V, connect the sup
-
ply to V
IN
and GND terminals using short (less than
10 inches) leads, preferably twisted leads. Connect a
suitable load to V
OUT
and GND terminals.
3. Slowly increase the input power supply to 10V. Observe
output voltage and verify that it meets the specifications
in the Performance Summary. Measure output voltage
with and without the load.
4. Move jumpers JP1 and JP2 to the other two fixed volt
-
age settings and verify that each output voltage meets
the values as shown in the Performance Summary.
5. Once the proper output voltages are established, adjust
the load and input voltage within the operating range
and observe the output voltage regulation, ripple volt
-
age and other parameters.
NOTES:
1.
IMPORTANT: 60V or higher voltage can result in an
electric shock if care is not taken. Also, hot plugging
the circuit to a power supply that has more than 40V
present at its output
can produce a high voltage tran-
sient
exceeding
the absolute maximum input voltage
which can damage the LTC3630A/LTC3630.
2. 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 V
IN
or V
OUT
and GND terminals. See Figure 3 for proper
scope probe technique.
Figure 1. Proper Measurement Equipment Setup
NOTE: A 10µF, 100V electrolytic capacitor is necessary when evaluating circuit
with input voltages greater than 40V, using long input wires and hot plugging
circuit into a powered input supply. See Figure 2.
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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
10.0010.0001 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
10.0010.0001 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
10.0010.0001 0.01 0.1
12V
IN
36V
IN
65V
IN
76V
IN
5V
OUT
Figure 4. Efficiency vs Load Current Curves

DC2105A-A

Mfr. #:
Manufacturer:
Analog Devices Inc.
Description:
Power Management IC Development Tools LTC3630AEMSE/LTC3630EMSE Demo Board - Hi
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
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