DEMO MANUAL DC1821B
40V, 1A Synchronous Buck-Boost DC/DC
Converter with Output Current Limit
Demonstration circuit 1821B features the LTC®3114-1, a In PWM mode, the LTC3114-1 operates at 1.2MHz to
wide operating range synchronous monolithic buck-boost optimize small size with high efficiency operation.
converter with programmable average output current. The demo board also incorporates diode D1 to backfeed
The DC1821B demo board has two user selectable operat- VCC to improve efficiency in some applications. If the
ing modes: Burst Mode® operation and Fixed Frequency demo board output voltage is changed to a higher volt-
PWM (JP2). There is also an accurate programmable RUN age, D1 should be removed. Consult the data sheet for
pin which is used to ENABLE the converter (JP1). more information.
The LTC3114-1 uses average current mode control to Figure 1 shows typical demo board efficiency. Figure 2
simplify voltage loop compensation and provide good line shows the response to an input voltage step while Figure 3
and load transient response. shows the load step response.
The DC1821B operates with a 2.7V to 40V input volt- The LTC3114-1 data sheet has detailed information about
age range. The demo board has been designed with the the operation, specifications, and applications of the part.
output voltage set to 5V. The LTC3114-1 incorporates a The data sheet should be read in conjunction with this
proprietary low noise switching algorithm which optimizes Quick Start Guide.
efficiency with input voltages above, below or equal to the Design files for this circuit board are available at
output voltage and ensures seamless transitions between http://www.linear.com/demo/DC1821B
operating modes. L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
PERFORMANCE SUMMARY Specifications are at TA = 25°C
Input Voltage Range 2.7V to 40V
IOUT (See Note 1) 1A for VIN > 6V
Efficiency See Figure 1
NOTE 1: The demo board output current is a function of VIN. Please refer to the data sheet for more information.
DEMO MANUAL DC1821B
DC1821B Typical Efficiency in
Auto Burst Mode Operation
EFFICIENCY (%) 80
60 250mA LOAD
50 1A LOAD
0 5 10 15 20 25 30 35 40
Figure 1. DC1821B Efficiency in Auto Burst Mode Operation
Figure 2. DC1821B Input Voltage Step Response. VIN Stepped from 3.3V to 12V IOUT is 500mA
Figure 3. DC1821B Step Load Response. VIN = 12V Load Step is from 250mA to 750mA
DEMO MANUAL DC1821B
QUICK START PROCEDURE
Using short twisted pair leads for any power connections 3. Connect a 500mA load to VOUT as shown in Figure 4
and with all loads and power supplies off, refer to Figure 4 (10Ω for VOUT = 5V). Connect an ammeter if accurate
for the proper measurement and equipment setup. The current measurement or monitoring is desired.
battery/power supply (PS1) should not be connected to 4. Turn on PS1 and slowly increase voltage until the volt-
the circuit until told to do so in the procedure below. age at VIN is 4V.
When measuring the input or output voltage ripple, care 5. Verify VOUT is ~5V.
must be taken to avoid a long ground lead on the oscil-
loscope probe. Measure the input or output voltage ripple 6. VIN can now be varied between 2.7V and 40V. IOUT
by touching the probe tip directly across the VIN or VOUT may need to be reduced for VIN < 4V.
and GND terminals (see Figure 5), or by using an oscil- 7. Load current (IOUT) can also be varied. The maximum
loscope probe tip jack. IOUT is a function of VIN and the current limit. Consult
1. Jumper and PS1 settings to start: the data sheet for more information on IOUT vs VIN. In
PS1: OFF general for VIN > 5V IOUT can be increased to 1A.
JP1: RUN ON 8. For operation in Burst Mode operation move Jumper
JP2 to BURST. See the data sheet for more information.
JP2: MODE FIXED FREQUENCY 9. NOTE: If VOUT drops out of regulation, check to be sure
2. With power OFF connect the power supply (PS1) as the maximum load has not been exceeded, or that VIN
shown in Figure 4. If accurate current measurements is not below the minimum value for regulation (see
are desired (for efficiency calculations for example) data sheet)
connect an ammeter in series with the supply as shown. 10.NOTE: If VOUT is changed to a voltage higher than 5V,
The ammeter is not required however. D1 should be removed or the LTC3114-1 could be
Figure 4. Proper Measurement Equipment Setup Figure 5. Measuring Input or Output Ripple
DEMO MANUAL DC1821B
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 2 C1, C2 CAP CER 0.068μF 16V 10% X7R 0402 TDK, C1005X7R1C683K
2 1 C3 CAP CER 4.7μF 6.3V X5R 20% 0603 TDK, C1608X5R0J475M
3 2 C4, C13 CAP CER 22μF 25V X7R 20% 1812 TDK, C4532X7R1E226M
4 1 C5 CAP CER 1.0μF 25V X5R 0603 TDK, C1608X5R1E105M
5 1 C6 CAP CER 10μF 50V 20% X7R 2220 TDK, C5750X7R1H106M230KB
6 1 C8 CAP CER 1.0μF 50V X7R 20% 1206 TDK, C3216X7R1H105M
7 1 C9 CAP CER 4700pF 25V X7R 10% 0402 TDK, C1005X7R1E472K
8 1 C10 CAP CER 10pF 50V C0G 0402 TDK, C1005C0G1H100D
9 1 C11 CAP CER 0.047μF 25V 20% X7R 0402 TDK, C1005X7R1E473M050BC
10 1 D1 DIODE SCHOTTKY 20V NXP, PMEG2010AEH
11 1 D2 DIODE SCHOTTKY 60V, 2A NXP, PMEG6020ER,115
12 1 L1 INDUCTOR, 6.8μH ±30% COILCRAFT, MSS1048-682NLB
13 1 R1 RES 2.00M 1/16W 1% 0402 SMD VISHAY, CRCW04022M00FKED
14 1 R2 RES 499k 1/16W 1% 0402 SMD VISHAY, CRCW0402499KFKED
15 1 R3 RES SMD 10k 1% 1/16W 0402 VISHAY,CRCW040210K0FKED
16 1 R4 RES 27.4k 1/16W 1% 0402 SMD VISHAY, CRCW040227K4FKED
17 1 R5 RES 1.00M 1/16W 1% 0402 SMD VISHAY, CRCW04021M00FKED
18 1 R8 RES 49.9Ω 1/16W 1% 0402 SMD VISHAY, CRCW040249R9FKED
19 1 U1 40V, 1A BUCK-BOOST DC/DC CONVERTER WITH LINEAR TECHNOLOGY, LTC3114MDHC-1
PROGRAMMABLE OUTPUT CURRENT
Additional Demo Board Circuit Components
20 0 C7 CAP 330μF 63V ELECT MVA SMD UNITED CHEMI-CON EMVA630ADA331MKG5S
21 0 C12 CAP CER 1000pF 25V X7R 0402 TDK, C1005X7R1E102M
22 0 C14 DNP
23 0 R6, R7 DNP
Hardware for Demo Board Only
24 4 E1, E2, E3, E4 TURRET, 0.09" DIA MILL-MAX, 2501-2-00-80-00-00-07-0
25 2 JP2, JP1 HEADERS, 3 PINS, 2mm CTRs SULLINS, NRPN031PAEN-RC
26 2 XJP1, XJP2 SHUNT, 2mm CTRs SAMTEC, 2SN-BK-G
27 4 STAND OFF STAND-OFF, NYLON 0.50" TALL KEYSTONE, 8832 (SNAP ON)
5 4 3 2 1 SCHEMATIC
L1 REVISION HISTORY
D2 ECO REV DESCRIPTION APPROVED DATE
PMEG6020ER 6.8uH - PRODUCTION J.NOON 6-6-16
C1 SW1 SW2 C2 E3
D VIN 68nF LTC3114-1 68nF VOUT VOUT D DIAGRAM
E1 13 BST1 BST2 12 R8 5.0V / 1A
2.7V - 40V 10 PVOUT 3 D1 1%
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- Information furnished by Linear Technology Corporation is believed to be accurate and reliable. VIN PMEG2010AEH
14 PLDO 11
PVIN C3 R1 R7
LDO 9 4.7uF LDO 2M DNP
RUN 4 RUN 7 C14 C4 C13 C5
C6 + C8 FB
C7 1uF DNP 22uF 22uF 1uF
C 10uF OPT 50V 16 6 25V 25V 25V C
50V MODE MODE VC R2
5 PROG 4700pF C10 1%
GND GND PGND 10pF
C11 R3 U1 R4
47nF 10k 8 17 1 27.4k
E2 GND E4
GND GND DEMO MANUAL
RUN VIN MODE LDO
B FIXED FREQ 1 B
ON 1 2
3 RUN BURST MODE
CUSTOMER NOTICE 1630 McCarthy Blvd.
APPROVALS Milpitas, CA 95035
Phone: (408)432-1900 www.linear.com
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; TECHNOLOGY Fax: (408)434-0507
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES. NC LTC Confidential-For Customer Use Only
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED APP ENG. J.NOON TITLE: SCHEMATIC
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT 40V, 1A SYNCHRONOUS BUCK - BOOST DC / DC CONVERTER
A PERFORMANCE OR RELIABILITY. CONTACT LINEAR A
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. WITH PROGRAMMABLE OUTPUT CURRENT DC1821B
SIZE IC NO. LTC3114-1EDHC REV.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND N/A DEMO CIRCUIT 1821B 1
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. SCALE = NONE DATE: 11 - 7 - 15 SHEET 1 OF 1
5 4 3 2 1
DEMO MANUAL DC1821B
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
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ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
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arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
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agency certified (FCC, UL, CE, etc.).
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Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application
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Copyright © 2004, Linear Technology Corporation
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