DEMO MANUAL DC2279A
LT3088EDD
800mA Single Resistor
Rugged Linear Regulator
DESCRIPTION
DC2279A is a linear regulator evaluation board featuring
LT
®
3088EDD,
which is a 36V
IN
, 800mA, rugged single
resistor programmable linear regulator.
The demo circuit operates over an input range of 1.6V to
36V. The LT3088 has a maximum output current of 800mA.
A key feature of the IC is the extended safe operation area
(SOA). The IC also features paralleled capability for higher
output current or heat spreading.
This device allows one single resistor to program output
voltage to any level between 0V and 34.5V if the load
current is larger than 2mA. Built-in protection includes
reverse battery protection, reverse current protection,
internal current limit and thermal limit.
DC2279A uses the LT3088EDD which is an 8-lead
(3mm × 3mm) plastic DFN package with an exposed pad on
the bottom-side of the IC for better thermal performance.
These features make DC2279A an ideal circuit for surface-
mount power supplies, rugged industrial power supplies,
low output voltage supplies, a post regulator for switching
supplies and intrinsic safety applications.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2279A
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.
BOARD PHOTO
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DEMO MANUAL DC2279A
PERFORMANCE SUMMARY
CONDITIONS
Shunt at 1.2V for JP1
Shunt at 1.5V for JP1
Shunt at 1.8V for JP1
Shunt at 2.5V for JP1
Shunt at 3.3V for JP1
Shunt at 5.0V for JP1
I
OUT
(mA)
100
800
100
800
100
800
100
800
100
800
100
800
Specifications are at T
A
= 25°C
V
IN
(V)
MIN
2.41
2.80
2.71
3.10
3.01
3.40
3.71
4.10
4.51
4.90
6.21
6.60
TYP
MAX*
36.0
5.6
36.0
6.0
36.0
6.3
36.0
7.0
36.0
7.8
36.0
9.5
MIN
1.17
1.17
1.46
1.46
1.75
1.75
2.43
2.43
3.20
3.20
4.85
4.85
V
OUT
(V)
TYP
1.20
1.20
1.50
1.50
1.80
1.80
2.50
2.50
3.30
3.30
5.00
5.00
MAX
1.25
1.25
1.56
1.56
1.88
1.88
2.60
2.60
3.44
3.44
5.20
5.20
*The maximum input voltage for 800mA load current is set by the 75°C temperature rise of LT3088 on the demo circuit. Higher input voltage can be
reached if larger copper area or force-air cooling is applied.
QUICK START PROCEDURE
DC2279A is easy to set up to evaluate the performance
of the LT3088. Refer to Figure 1 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 terminals
of the input or output capacitors. See Figure 2 for proper
scope probe technique.
1. Use JP1 to set the desired output voltage.
2. With power off, connect the input power supply to V
IN
and GND.
3. Turn on the power at the V
IN
.
NOTE:
Make sure that the V
IN
voltage does not ex-
ceed 36V.
4. Check for the proper output voltages.
NOTE:
If there is no output, temporarily disconnect the
load to make sure that the load is not set too high or
is shorted.
5. Once the proper output voltages are established, ad-
just the loads within the operating range and observe
the output voltage regulation, efficiency and other
parameters.
NOTE:
Make sure that the power dissipation is limited
below the thermal limit.
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dc2279af
DEMO MANUAL DC2279A
QUICK START PROCEDURE
Figure 1. Test Procedure Setup Drawing for DC2279A
+
V
OUT
C
OUT
GND
–
Figure 2. Measuring Input and Output Ripple
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DEMO MANUAL DC2279A
THERMAL IMAGE
An example thermal image shows the temperature distribu-
tion on the PC board. The test is done in still air at room
temperature with 2.5W power dissipation in the LT3088 IC.
This gives an IC case-to-ambient thermal resistance of
θ
CA
= 18°C/W on the demo circuit. The IC, at its highest
point reaches 66°C, at 4.4V
IN
, 1.2V
OUT
, 800mA load current.
Figure 3. Temperature Rise at 2.5W Dissipation (V
IN
= 4.4V, V
OUT
= 1.2V, I
OUT
= 800mA)
PARTS LIST
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
QTY
1
1
1
1
1
1
1
1
1
1
1
1
1
0
4
1
1
REFERENCE
C1
C2
C3
R1
R2
R3
R4
R5
R6
R7
R8
U1
C4
R9 (OPT)
E1, E2, E3, E4
JP1
XJP1
PART DESCRIPTION
CAP, X7R, 1μF, 50V, 10% 0805
CAP, X5R, 10μF, 50V, 10% 1206
CAP, C0G, 0.01μF, 50V, 5% 0603
RES., CHIP, 301k, 1/10W, 1% 0603
RES., CHIP, 560Ω, 1/4W, 5% 1206
RES., CHIP, 26.1k, 1/10W, 1% 0603
RES., CHIP, 33.2k, 1/10W, 1% 0603
RES., CHIP, 41.2k, 1/10W, 1% 0603
RES., CHIP, 60.4k, 1/10W, 1% 0603
RES., CHIP, 84.5k, 1/10W, 1% 0603
RES., CHIP, 150k, 1/10W, 1% 0603
IC., LT3088EDD DFN-8 (3 × 3)
CAP., ALUM, 10µF, 50V 5 × 5.4mm
RES., 0603
TESTPOINT, TURRET, 0.094" PBF
2 × 7, 0.079" DOUBLE ROW HEADER
SHUNT, 0.079" CENTER
MILL-MAX, 2501-2-00-80-00-00-07-0
SULLINS, NRPN072PAEN-R
SAMTEC, 2SN-BK-G
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MANUFACTURER/PART NUMBER
MURATA, GRM21BR71H105KA12L
MURATA, GRM31CR61H106KA12L
MURATA, GRM1885C1H103JA01J
VISHAY, CRCW0603301KFKEA
VISHAY, CRCW1206560RJNEA
VISHAY, CRCW060326K1FKEA
VISHAY, CRCW060333K2FKEA
VISHAY, CRCW060341K2FKEA
VISHAY, CRCW060360K4FKEA
VISHAY, CRCW060384K5FKEA
VISHAY, CRCW0603150KFKEA
LINEAR TECH., LT3088EDD#PBF
SUN SELECT., 50CE10BSS
Required Circuit Components
Additional Demo Board Circuit Components
Hardware: For Demo Board Only
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DEMO MANUAL DC2279A
SCHEMATIC DIAGRAM
dc2279af
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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Analogue and Mixed Signal
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