1
Rev. 0
DEMO MANUAL DC1687B
DESCRIPTION
LTC3115-1
40V, 2A Synchronous
Buck-Boost DC/DC Converter
Demonstration circuit 1687B features the LTC
®
3115-1, a
high voltage monolithic synchronous buck-boost converter.
The DC1687B 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 DC1687B operates with a 2.7V to 40V input volt-
age range. The demo board has been designed with the
output voltage set to 5V. 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.
All registered trademarks and trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
The demo board also has optional provisions to back
feed VCC in order to increase efficiency in some 5V out-
put applications. There is also a provision for an optional
Schottky diode from SW2 to VOUT for applications where
VOUT 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.
PARAMETER VALUE
Input Voltage Range 2.7V to 40V
VOUT 5.0V
IOUT (See Note 1) 1A For VIN ≥ 3.6V,
2A For VIN > 6V
Efficiency See Figures 1 and 2
Note 1: The Demo Board output current is a function of VIN. Please refer to the data sheet for more information
Note: This manual is intended to be used with an updated version of the demo board titled,
“Demo Circuit 1687B.” See Figure3.
2
Rev. 0
DEMO MANUAL DC1687B
QUICK START PROCEDURE
Using short twisted pair leads for any power connections
and with all loads and power supplies off, refer to Figure3
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 VIN or VOUT
and GND terminals (see Figure4), 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 Figure3 . 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.
3. Connect a 500mA load to VOUT as shown in Figure3
(10Ω for VOUT = 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 VIN is 4.0V.
5. Verify VOUT is ~5.0V.
6. VIN can now be varied between 2.7V and 40V. IOUT may
need to be reduced for VIN < 4V. VOUT should remain in
regulation.
7. Load current (IOUT) can also be varied. The maximum
IOUT is a function of VIN and the current limit. Consult
the data sheet for more information on IOUT vs VIN. In
general for VIN > 3.6V IOUT can be increased to 1A. For
VIN > 6V IOUT can be increased to 2A.
8. For Burst Mode operation, move Jumper JP1 to burst.
IOUT is limited in Burst Mode operation. See the data
sheet for more information.
9. NOTE: If VOUT drops out of regulation, check to be sure
the maximum load has not been exceeded, or that VIN
is not below the minimum value for regulation (see data
sheet)
0
100
90
80
70
60
50
5 10 15 20 25 30 35 40
EFFICIENCY (%)
VIN (V)
LOAD = 1A
LOAD = 500mA
0
100
90
80
70
60
50
5 10 15 20 25 30 35 40
EFFICIENCY (%)
VIN (V)
LOAD = 300mA
LOAD = 200mA
LOAD = 100mA
Figure1. DC1687B Efficiency in PWM Mode Figure2. DC1687B Efficiency in Burst Mode Operation
4
Rev. 0
DEMO MANUAL DC1687B
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 2 C1,C2 CAP CER 0.10uF 16V X7R ±20% 0402 TDK, C1005X7R1C104M
2 1 C4 CAP CER 33pF 50V C0G 5% 0402 TDK, C1005C0G1H330J
3 1 C6 CAP CER 47uF 10V 20% X5R 1812 TDK, C4532X5R1A476M
4 1 C7 CAP CER 1.0uF 25V X5R 0603 TDK, C1608X5R1E105M
5 1 C8 CAP CER 3300pF 50V 5% NP0 0603 TDK, C1608C0G1H332J
6 1 C9 CAP CER 4.7uF 6.3V X5R 20% 0603 TDK, C1608X5R0J475M
7 1 C10 CAP CER 4.7uF 50V 20% X7R 1812 TDK, C4532X7R1H475M/2.00
8 1 C11 CAP CER 10pF 50V C0G 0402 TDK, C1005C0G1H100D
9 1 C12 CAP CER 1.0uF 50V X7R 20% 1206 TDK, C3216X7R1H105M
10 1 C13 CAP CER 0.1uF 50V 20% X7R 0805 TDK, C2012X7R1H104M/0.85
11 1 C14 CAP CER 1UF 50V X5R 0402 TAIYO YUDEN, UMK105CBJ105MV-F
12 2 C15,C16 CAP CER 0.1UF 50V X7R 0402 TDK, CGA2B3X7R1H104K050BB
13 1 L1 INDUCTOR, 10uH, +/-20% COILCRAFT, MSS1048-103MLB
14 2 R1,R6 RES, 1.00M OHM 1/16W 1% 0402 SMD VISHAY, CRCW04021M00FKED
15 1 R2 RES, 249k OHM 1/10W 1% 0402 SMD VISHAY, CRCW0402249KFKED
16 1 R3 RES, 15.0k OHM 1/10W 1% 0402 SMD PANASONIC, ERJ-2RKF1502X
17 1 R4 RES, 60.4k OHM 1/10W 1% 0402 SMD PANASONIC, ERJ-2RKF6042X
18 1 R7 RES, 47.5k OHM 1/10W 1% 0402 SMD VISHAY, CRCW040247K5FKED
19 1 U1 40V, 2A BUCK BOOST DC/DC CONVERTER ANALOG DEVICES, LTC3115EDHD-1
Additional Demo Board Circuit Components
1 0 C3 CAP CER 1000PF 50V 20% X7R 0402 (OPT) TDK, C1005X7R1H102M
2 0 C5 CAP ALUM 150uF 50V 20% RADIAL (OPT) PANASONIC, EEU-FM1H151
3 0 C17 CAP CER 1210 (OPT)
4 0 C18,C19 CAP CER 1206 4.7uF (OPT)
5 0 D2 DIODE SCHOTTKY 60V 3A SMA (OPT) DIODES INC.,B360A-13
6 1 D1 DIODE SCHOTTKY, 20V 1A SOD323 (OPT) NXP SEMI, PMEG2010EA
7 0 R5 RES, 0402 (OPT)
8 0 L2 INDUCTOR, 2.2uH (OPT) COILCRAFT XAL60XX SERIES
9 0 FB1 FERRITE BEAD (OPT) WURTH, 782853121
Hardware For Demo Board Only
1 5 E1-E5 TP, TURRET, 0.094", PBF MILL-MAX, 2501-2-00-80-00-00-07-0
2 2 JP1, JP2 JMP, 3PIN 1 ROW .079CC SAMTEC, TMM-103-02-L-S
3 2 XJP1,XJP2 SHUNT, .079" CENTER SAMTEC, 2SN-BK-G
4 4 SPACER STACKING #4 SCREW NYLON .500" KEYSTONE, 8833
5
Rev. 0
DEMO MANUAL DC1687B
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog
Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications
subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
SCHEMATIC DIAGRAM
A
A
B
B
C
C
D
D
E
E
4 4
3 3
2 2
1 1
OPT
0805
FIXED FREQ
BURST MODE
SYNCH
OFF
ON
0603
UNLESS NOTED:
RESISTORS: OHMS, 0402, 1%
CAPACITORS: uF, 0402
RUN
PWM
OPTIONAL EMI FILTER
REVISION HISTORY
ECO REV DESCRIPTION APPROVED DATE
-1 PROTOTYPE
40V, 2A BUCK BOOST DC / DC CONVERTER
JN 04-29-19
DATE:
IC NO.
SHEET OF
TITLE: DEMO CIRCUIT SCHEMATIC,
APPROVALS
PCB DES.
APP ENG.
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
SIZE:
SKU NO.
SCHEMATIC NO. AND REVISION:
PCA ASS'Y DWG:
www.analog.com
11
NC
JN
LTC3115-1
DC1687B
710-DC1687B_REV01
705-DC1687B_REV01
8.5x11
04-18-19DATE:
IC NO.
SHEET OF
TITLE: DEMO CIRCUIT SCHEMATIC,
APPROVALS
PCB DES.
APP ENG.
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
SIZE:
SKU NO.
SCHEMATIC NO. AND REVISION:
PCA ASS'Y DWG:
www.analog.com
11
NC
JN
LTC3115-1
DC1687B
710-DC1687B_REV01
705-DC1687B_REV01
8.5x11
04-18-19DATE:
IC NO.
SHEET OF
TITLE: DEMO CIRCUIT SCHEMATIC,
APPROVALS
PCB DES.
APP ENG.
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
SIZE:
SKU NO.
SCHEMATIC NO. AND REVISION:
PCA ASS'Y DWG:
www.analog.com
11
NC
JN
LTC3115-1
DC1687B
710-DC1687B_REV01
705-DC1687B_REV01
8.5x11
04-18-19
C6
47uF
10V
1812
R6
1M
C11
10pF
L2
OPT
Coilcraft XAL-6030
R1
1M
C10
4.7uF
50V
1812
C16
.1uF
50V
C12
1uF
50V
1206
C7
1uF
25V
0603
C14
1uF
50V
E1
VOUT
5.0V / 2A
R4
60.4k
C1
0.1uF
C3
OPT
L1
10uH
E5
VIN_EMI
2.7V - 40V
E2
GND
R7
47.5k
FB1
C4
33pF
JP1
1
2
3
C19
OPT
1206
D1
PMEG2010EA
OPT
JP2
1
2
3
U1
LTC3115EDHD-1
VIN
10
PVIN
14
PVCC
11
VCC
9
RUN 1
PWM/SYNC
16
GND
5
RT
8
GND
4
PGND
17
PVOUT 3
VC 6
FB 7
BST1
13
SW1 15
BST2 12
SW2 2
R2
249k
C18
OPT
1206
C17
OPT
1210
C8
3300pF
C2
0.1uF
+
C5
OPT
C15
.1uF
50V
C9
4.7uF
6.3V
0603
D2
B360A
OPT
R5
OPT
R3
15k
E4
GND
C13
0.1uF
0805
E3
VIN
2.7V - 40V
VIN
VIN
VOUT
VOUT VCC
PWM
RT
RUN
VIN
RUN
VCC
PWM
6
Rev. 0
DEMO MANUAL DC1687B
ANALOG DEVICES, INC. 2012–2019
05/19
www.analog.com
ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection
circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.
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