DEMO MANUAL DC1687A
LTC3115EDHD-1
40V, 2A Synchronous
Buck-Boost DC/DC Converter
Description
Demonstration circuit 1687A features the LTC
®
3115-1, a
high voltage monolithic synchronous buck-boost converter.
The DC1687A demo board has two user selectable operat-
ing modes: Burst Mode
®
operation and forced continuous
operation (fixed frequency PWM) (JP1). There is also an
accurate programmable RUN pin which is used to enable
the converter (JP2).
The DC1687A operates with a 2.7V to 40V input volt-
age range. The demo board has been designed with the
output voltage set to 5.0V. The LTC3115-1 incorporates a
proprietary low noise switching algorithm which optimizes
efficiency with input voltages above, below or equal to the
output voltage and ensures seamless transitions between
operating modes.
The demo board has been programmed to operate at 1MHz
in PWM mode to optimize small size with high efficiency
operation.
The demo board also has optional provisions to back
feed V
CC
in order to increase efficiency in some 5V out-
put applications. There is also a provision for an optional
Schottky diode from SW2 to V
OUT
for applications where
V
OUT
is greater than 20V and short circuit protection is
desired. Consult the data sheet for more information on
these options.
Figures 1 and 2 show typical demo board efficiency.
The LTC3115-1 data sheet has detailed information about
the operation, specifications, and applications of the part.
The data sheet should be read in conjunction with this
quick start guide.
Design files for this circuit board are available at
http://www.linear.com/demo
L,
LT, LTC, LTM, µModule, Burst Mode, 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
PARAMETER
Input Voltage Range
V
OUT
I
OUT
(See Note 1)
Efficiency
VALUE
2.7V to 40V
5.0V
1A For V
IN
≥ 3.6V,
2A For V
IN
> 6V
See Figures 1 and 2
Note 1: The Demo Board output current is a function of V
IN
. Please refer to the data sheet for more information
dc1687af
1
DEMO MANUAL DC1687A
Quick start proceDure
Using short twisted pair leads for any power connections
and with all loads and power supplies off, refer to Figure 3
for the proper measurement and equipment setup. The
battery/power supply (PS1) should not be connected to
the circuit until told to do so in the procedure below.
When measuring the input or output voltage ripple, care
must be taken to avoid a long ground lead on the oscil-
loscope 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 4), or by using an oscil-
loscope probe tip jack.
1. Jumper and PS1 settings to start:
PS1 = OFF
JP1 (PWM) = fixed frequency
JP2 (RUN) = ON
2. With power OFF connect the power supply (PS1) as
shown in Figure 3. If accurate current measurements
are desired (for efficiency calculation for example) then
connect an ammeter in series with the supply as shown.
The ammeter is not required however.
100
3. Connect a 500mA load to V
OUT
as shown in Figure 3
(10Ω for V
OUT
= 5V). Connect an ammeter if accurate
current measurement or monitoring is desired.
4. Turn on PS1 and slowly increase voltage until the volt-
age at V
IN
is 4.0V.
5. Verify V
OUT
is ~5.0V.
6. V
IN
can now be varied between 2.7V and 40.0V. I
OUT
may
need to be reduced for V
IN
< 4V. V
OUT
should remain in
regulation.
7. Load current (I
OUT
) can also be varied. The maximum
I
OUT
is a function of V
IN
and the current limit. Consult
the data sheet for more information on I
OUT
vs V
IN
. In
general for V
IN
> 3.6V I
OUT
can be increased to 1A. For
V
IN
> 6V I
OUT
can be increased to 2A.
8. For operation in Burst Mode operation move Jumper
JP1 to burst. I
OUT
is limited in Burst Mode operation.
See the data sheet for more information.
9. NOTE: If V
OUT
drops out of regulation, check to be sure
the maximum load has not been exceeded, or that V
IN
is not below the minimum value for regulation (see data
sheet)
100
90
EFFICIENCY (%)
EFFICIENCY (%)
90
80
80
70
70
60
50
LOAD = 500mA
LOAD = 1A
0
5
10
15
20
V
IN
(V)
25
30
35
40
60
50
LOAD = 100mA
LOAD = 200mA
LOAD = 300mA
0
5
10
15
20
V
IN
(V)
25
30
35
40
Figure 1. DC1687A Efficiency in PWM Mode
Figure 2. DC1687A Efficiency in Burst Mode Operation
dc1687af
2
DEMO MANUAL DC1687A
Quick start proceDure
Figure 3. Proper Measurement Equipment Setup
Figure 4. Measuring Input or Output Ripple
VIN
GND
dc1687af
3
DEMO MANUAL DC1687A
parts List
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
1
2
3
4
5
1
2
3
4
QTY
2
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
0
0
0
0
0
4
2
2
4
REFERENCE
C1, C2
C4
C6
C7
C8
C9
C10
C11
C12
C13
L1
R1, R6
R2
R3
R4
R7
U1
C3
C5
D1
D2
R5
E1–E4
JP1, JP2
XJP1, XJP2
PART DESCRIPTION
CAP CER, 0.10µF 16V, X7R, ±20%, 0402
,
,
CAP CER, 33pF 50V, C0G, 5%, 0402
,
,
CAP CER, 47µF 10V, 20%, X5R, 1812
,
,
CAP CER, 1.0µF 25V, X5R, 0603
,
,
CAP CER, 3300pF 50V, 5%, NP0, 0603
,
,
CAP CER, 4.7µF 6.3V, X5R, 20%, 0603
,
,
CAP CER, 4.7µF 50V, 20%, X7R, 1812
,
,
CAP CER, 10pF 50V, C0G, 0402
,
,
CAP CER, 1.0µF 50V, X7R, 20%, 1206
,
,
CAP CER, 0.1µF 50V, 20%, X7R, 0805
,
,
INDUCTOR, 10µH, ±20%
RES, 1.00MΩ, 1/16W, 1%, 0402, SMD
RES, 249kΩ, 1/16W, 1%, 0402, SMD
RES, 15.0kΩ, 1/10W, 1%, 0402, SMD
RES, 60.4kΩ, 1/10W, 1%, 0402, SMD
RES, 47.5kΩ, 1/16W, 1%, 0402, SMD
40V, 2A Buck Boost DC/DC Converter
CAP CER, 1000PF 50V, 20%, X7R, 0402 (OPT)
,
,
CAP ALUM, 150µF 50V, 20%, RADIAL (OPT)
,
,
DIODE SCHOTTKY, 20V, 1A, SOD323 (OPT)
DIODE SCHOTTKY, 60V, 3A, SMA (OPT)
RES, 0402 (OPT)
TP TURRET, 0.094", PBF
,
JMP 3-PIN 1 ROW .079CC
,
SHUNT, .079" CENTER
SPACER STACKING #4 SCREW NYLON .500"
MILL-MAX, 2501-2-00-80-00-00-07-0
SAMTEC, TMM-103-02-L-S
SAMTEC, 2SN-BK-G
KEYSTONE, 8833
MANUFACTURER/PART NUMBER
TDK, C1005X7R1C104M
TDK, C1005C0G1H330J
TDK, C4532X5R1A476M
TDK, C1608X5R1E105M
TDK, C1608C0G1H332J
TDK, C1608X5R0J475M
TDK, C4532X7R1H475M/2.00
TDK, C1005C0G1H100D
TDK, C3216X7R1H105M
TDK, C2012X7R1H104M/0.85
COILCRAFT, MSS1048-103MLB
VISHAY, CRCW04021M00FKED
VISHAY, CRCW0402249KFKED
PANASONIC, ERJ-2RKF1502X
PANASONIC, ERJ-2RKF6042X
VISHAY, CRCW040247K5FKED
LINEAR TECHNOLOGY, LTC3115EDHD-1
TDK, C1005X7R1H102M
PANASONIC, EEU-FM1H151
NXP SEMI, PMEG2010EA
DIODES INC.,B360A-13
Required Circuit Components
Additional Demo Board Circuit Components
Hardware For Demo Board Only:
dc1687af
4
A
B
C
D
ECO
D2
L1
10uH
15
SW1
SW2
REV
2
PRODUCTION FAB
E1
VOUT
5.0V / 2A
4
REVISION HISTORY
DESCRIPTION
J.NOON
02-08-12
E
APPROVED
DATE
-
B360A
OPT
C2
0.1uF
12
3
4
C1
0.1uF
VIN
13
BST1
VIN
PVIN
PVCC
VCC
PWM/SYNC
GND
VC
6
RT
RUN
1
FB
7
PVOUT
BST2
10
14
11
9
16
5
8
2
E3
D1
PMEG2010EA
VOUT
VOUT
R1
1M
C8
3300pF
0603
C11
10pF
R3
15k
OPT
VCC
PWM
C13
0.1uF
0805
RUN
R4
60.4k
C4
33pF
schematic Diagram
VIN
2.7V - 40V
3
3
C5
+
C10
4.7uF
50V
1812
4
GND
17
OPT
C12
1uF
50V
1206
C9
4.7uF
6.3V
0603
R7
47.5k
U1
LTC3115EDHD-1
PGND
C6
47uF
10V
1812
C7
1uF
25V
0603
R2
249k
E2
GND
2
E4
2
GND
VIN
RUN
ON
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.
OFF
1
2
RUN
3
R6
1M
UNLESS NOTED:
RESISTORS: OHMS, 0402, 1%
CAPACITORS: uF, 0402
JP2
R5
C3
CUSTOMER NOTICE
APPROVALS
NC
J.NOON
OPT
OPT
TECHNOLOGY
TITLE: SCHEMATIC
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
1
PWM
FIXED FREQ
SYNCH
BURST MODE
B
1
2
3
VCC
PWM
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APP ENG.
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
40V, 2A BUCK BOOST DC / DC CONVERTER
SIZE
SCALE = NONE
C
1
JP1
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
N/A
DATE:
IC NO.
02-08-12
REV.
LTC3115EDHD-1
DEMO CIRCUIT 1687A
D
2
SHEET
E
1
OF
1
A
DEMO MANUAL DC1687A
dc1687af
5
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