1
dc1865af
DEMO MANUAL DC1865A
Description
LT3055
500mA, Linear Regulator with
Precision Current Limit and Diagnostics
Demonstration circuit 1865A is an adjustable 500mA linear
regulator featuring
LT
®
3055
. LT3055 is a micropower, low
noise and low dropout voltage linear regulator. The device
supplies 500mA of output current with a dropout voltage
of 350mV. A 10nF bypass capacitor reduces output noise
to 25µV
RMS
in a 10Hz to 100kHz bandwidth and soft-starts
the reference. The LT3055’s ±45V input voltage rating
combined with its precision current limit and diagnostic
functions make the IC an ideal choice for robust, high
reliability applications.
LT3055 current limit can be programmed by a single
resistor, accurate to ±10% over a wide input voltage
and temperature range. Another resistor programs the
LT3055’s minimum output current monitor, useful for
detecting open-circuit conditions. The internal current limit
should be considered when the input-to-output differential
is high. The current monitor function sources a current
equal to 1/500th of output current. See the Operation sec-
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
tion in the data sheet for a detailed calculation. Logic fault
pins assert low if the LT3055 is in current limit (
FAULT2
),
operating below its minimum output current (
FAULT1
)
or is in thermal limit (both
FAULT1
and
FAULT2
). The die
temperature is indicated by the TEMP pin.
LT3055 optimizes stability and transient response with a
low ESR ceramic capacitor, requiring a minimum of 3.3µF.
The LT3055 is available in the thermally-enhanced 16-lead
4mm × 3mm DFN and MSOP packages.
The LT3055 data sheet gives a complete description of
the device, operation and application information. The
data sheet must be read in conjunction with this quick
start guide for DC1865.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1865A
PARAMETER
CONDITIONS
VALUE
Minimum Input Voltage (Max)
V
OUT
= 5V, I
OUT
= 500mA
5.6V
Maximum Input Voltage
V
OUT
= 5V
45V
Output Voltage V
OUT
Header in JP1
Header in JP2
Header in JP3
Header in JP4
Header in JP5
Header in JP6
1.20V ±3%
1.50V ±3%
1.80V ±3%
2.50V ±3%
3.32V ±3%
4.99V ±3%
Maximum Output Current (Typ)
V
IN
= 12V, V
OUT
= 5V, R10 = 604Ω
500mA
Minimum Output Current (Typ)
V
IN
= 12V, V
OUT
= 5V, R9 = 121kΩ
10mA
I
MON
Voltage (to µP ADC) (Typ)
V
IN
= 12V, V
OUT
= 5V, R8 = 1k, I
OUT
= 500mA
1V
Temp voltage (Typ)
V
IN
= 12V, V
OUT
= 5V
0.25V
Specifications are at T
A
= 25°C
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