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dc1863af
DEMO MANUAL DC1863A
DESCRIPTION
LTC3621
17V, 1A Monolithic Synchronous
Step-Down Regulator
Demonstration circuit 1863 is a step-down converter,
capable of delivering up to 1A of output current from a
minimum input voltage of 2.7V. The DC1863A uses the
power-saving LT C
®
3621 1MHz monolithic synchronous
buck regulator in a small 8-lead MS8 package. The
LTC3621 IC quiescent currents can be as low as 3.5μA
in normal operation, and less than 0.1μA in shut down.
The output voltage range of the DC1863A is from as low
as 0.6V, the reference voltage of the LTC3621, to as high
as the maximum input voltage, 17V. The DC1863A can
operate in three distinct operating modes: Burst Mode
®
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
owners.
PERFORMANCE SUMMARY
operation for highest efficiency at low output currents,
forced continuous mode for lowest output ripple voltage,
and pulse-skipping mode for the best compromise opera-
tion between the two other modes, by setting the mode
pin to INTVCC (3.6V), INTVCC/2, or ground respectively.
All these features make the DC1863A an ideal circuit for
use in any high efficient, low power application.
Design files for this circuit board are available at
http://www.linear.com/demo
Specifications are at TA = 25°C
PARAMETER CONDITIONS VALUE
Input Voltage Range 2.7V to 17V
Output Voltage Range 0.6V to VIN
Run/Shutdown RUN Pin = GND Shutdown
RUN Pin = VIN Operating
Output Voltage Regulation VIN = 2.7V to 17V, IOUT = 0A to 1A 1.2V ±3% Typ (1.164V to 1.236V)
VIN = 2.7V to 17V, IOUT = 0A to 1A 1.8V ±3% Typ (1.746V to 1.854V)
VIN = 2.7V to 17V, IOUT = 0A to 1A 2.5V ±3% Typ (2.425V to 2.575V)
VIN = 3.5V to 17V, IOUT = 0A to 1A 3.3V ±3% Typ (3.201V to 3.399V)
VIN = 5.2V to 17V, IOUT = 0A to 1A 5V ±3% Typ (4.85V to 5.15V)
Typical Output Ripple Voltage VIN = 12V, VOUT = 5V, IOUT = 1A (20MHz BW) <20mVP–P
Nominal Switching Frequency 1MHz ± 8%
Operation Modes MODE Pin = INTVCC Burst Mode
MODE Pin = GND Pulse-Skipping
MODE Pin = INTVCC/2 Forced Continuous
Burst Mode-to-CCM Operation VIN = 12V, VOUT = 1.2V IOUT < 500mA
INTVCC 3.6V ±8.33% (3.3V to 3.9V)
Table 2. Jumper Description
JUMPER FUNCTION/RANGE SETTING
JP1 Run: ON–OFF. ON
JP2 Mode: Burst Mode Operation (BM) or Pulse-
Skipping Mode (PS).
BM
JP3 Output Voltage Setting 1.2V
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dc1863af
DEMO MANUAL DC1863A
QUICK START PROCEDURE
Demonstration Circuit 1863 is easy to set up to evaluate
the performance of the LTC3621. For proper measurement
equipment configuration, set up the circuit according to
the diagram in Figure 1. Before proceeding to test, check
that the shunts are inserted into the correct locations:
1.2V position of the output voltage header JP3, into the
BM (Burst Mode operation) position of MODE header JP2,
and into the ON position of RUN header JP1.
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 Figure 2 for proper scope probe
measurement technique.
With the DC1863 set up according to the proper measure-
ment configuration and equipment in Figure 1, apply 5V at
VIN (Do not hot-plug VIN or increase VIN over the rated
maximum supply voltage of 17V, or the part may be dam-
aged.). Measure VOUT; it should read 1.2V (If desired, the
quiescent current of the circuit can be monitored now by
swapping the shunt in header JP1 into the OFF position).
The output voltage should be regulating. Draw 500mA out
of the output and measure VOUT—it should measure 1.2V
±2% (1.176V to 1.224V). Verify the switching frequency
is between 920kHz and 1.08MHz (T = 1.08μs and 926ns),
and that the switch node waveform is rectangular in shape.
Vary the input voltage from 2.7V to 17V and the load cur-
rent from 0 to 1A. VOUT should regulate around 1.2V ±3%
(1.164V to 1.236V). Measure the output ripple voltage; it
should measure less than 20mV AC.
Set the input voltage to 12V and the output current to than
100mA. Observe the Burst Mode operation at the switch
node (the pad of the inductor opposite from the output),
and measure the output ripple voltage. It should measure
less than 100mV. Change the shunt position on the MODE
header from BM to PS (pulse-skipping mode) and observe
the voltage waveform at the switch pins. To achieve forced
continuous operation, insert two 100k resistors at the
pads for R1 and R2. These resistors develop a voltage of
INTVCC/2 at the mode pin, which is the voltage setting for
forced continuous operation.
Insert the JP1 shunt into the OFF position and move the
shunt in the 1.2V output JP3 header into any of the re-
maining output voltage option headers: 1.8V (JP4), 2.5V
(JP5), 3.3V (JP6) or 5V (JP7). Just as in the 1.2V VOUT
test, the output voltage should read VOUT ±2% tolerance
under static line and load conditions and ±1% tolerance
under dynamic line and load conditions (±3% total). Also,
the circuit switch operation in Burst or pulse-skipping
mode will remain the same. There is an extra output volt-
age header, JP8, to allow the user to easily set the output
to their desired value
When finished, turn off the circuit by inserting the shunt
in header JP1 into the OFF position.
Figure 1. Proper Equipment Measurement Setup
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dc1863af
DEMO MANUAL DC1863A
QUICK START PROCEDURE
EFFICIENCY DATA
Figure 2. Measuring Input or Output Ripple
Figure 3. Efficiency vs Load Current
VIN = 12V
Burst Mode OPERATION
fSW = 1MHZ
L = 4.7μH COILCRAFT XFL-4020
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dc1863af
DEMO MANUAL DC1863A
LOAD STEP RESPONSE WAVEFORMS
VOUT
50mV/DIV
AC-COUPLED
IOUT
500mA/DIV
50μs/DIVVIN = 12V
VOUT = 1.2V
500mA LOAD STEP (500mA TO 1A)
PULSE-SKIPPING MODE
fSW = 1MHz
Figure 4
Figure 5
Figure 6
VOUT
50mV/DIV
AC-COUPLED
IOUT
500mA/DIV
50μs/DIVVIN = 12V
VOUT = 1.8V
500mA LOAD STEP (500mA TO 1A)
PULSE-SKIPPING MODE
fSW = 1MHz
VOUT
50mV/DIV
AC-COUPLED
IOUT
500mA/DIV
50μs/DIVVIN = 12V
VOUT = 2.5V
500mA LOAD STEP (500mA TO 1A)
PULSE-SKIPPING MODE
fSW = 1MHz
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dc1863af
DEMO MANUAL DC1863A
LOAD STEP RESPONSE WAVEFORMS
Figure 7
Figure 8
VOUT
100mV/DIV
AC-COUPLED
IOUT
500mA/DIV
50μs/DIVVIN = 12V
VOUT = 3.3V
500mA LOAD STEP (500mA TO 1A)
PULSE-SKIPPING MODE
fSW = 1MHz
VOUT
100mV/DIV
AC-COUPLED
IOUT
500mA/DIV
50μs/DIVVIN = 12V
VOUT = 5V
500mA LOAD STEP (500mA TO 1A)
PULSE-SKIPPING MODE
fSW = 1MHz
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dc1863af
DEMO MANUAL DC1863A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 CFF CAP., X7R, 22pF, 50V, 0402 AVX 04025A220KAT
2 1 C1 CAP., X5R, 10μF, 25V, 10%, 1206 AVX 12063D106KAT
3 2 C2, C3 CAP., X5R, 22μF, 25V, 10%, 1206 AVX 12063D226KAT
4 1 C4 CAP., X5R, 1μF, 6.3V,20%, 0402 TDK, C1005X5R0J105M
5 1 L1 IND., FIXED INDUCTOR, 4.7μH COILCRAFT XFL4020-472MEB
6 2 R3, Rset RES., CHIP, 619k, 1%, 0402 VISHAY CRCW0402619KFKED
7 1 U1 LTC3621EMS8E, MS8 PACKAGE, 8-LEAD, MSOP LINEAR TECH. LTC3621EMS8E#PBF
Additional Demo Board Circuit Components
1 1 C1A CAP., X5R, 8.2μF 20V, SIZE B2, 3528-7343 SANYO 20TQC8R2M
2 0 R1, R2 OPT RES., CHIP, 0402
3 1 Rpgood RES., CHIP, 100k, 1%, 0402 VISHAY CRCW0402100K0FKED
4 1 R4 RES., CHIP, 309k, 1%, 0402 VISHAY CRCW0402309KFKED
5 1 R5 RES., CHIP, 196k, 1%, 0402 VISHAY CRCW0402196KFKED
6 1 R6 RES., CHIP, 137k, 1%, 0402 VISHAY CRCW0402137KFKED
7 1 R7 RES., CHIP, 84.5k, 1%, 0402 VISHAY CRCW040284K5FKED
8 0 R8 OPT RES., CHIP, 0402
Hardware
1 8 E1-E8 TESTPOINT, TURRET, 0.095" MILL-MAX 2501-2-00-80-00-00-07-0
2 2 JP1, JP2 2MM SINGLE ROW HEADER, 3-PIN SULLINS NRPN031PAEN-RC
3 6 JP3-JP8 2MM SINGLE ROW HEADER, 2-PIN SULLINS NRPN021PAEN-RC
4 3 JP1-JP3 SHUNT SAMTEC 2SN-BK-G
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dc1863af
DEMO MANUAL DC1863A
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.
SCHEMATIC DIAGRAM
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
VOUT
2.7V - 17V
ON
OFF
1A
VIN
1.2V 1.8V 2.5V 3.3V 5.0V USER
SELECT
RUN
GND
TOM G.
WITH ULTRA-LOW QUIESCENT CURRENT
GND
PS (Pulse-Skip)
MODE/SYNC
GND
INTVCC
(Forced Continuous)
BM (Burst Mode)
PGOOD
SYNC
VIN VOUT
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
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
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Thursday, June 13, 2013
11
17V VIN SYNCHRONOUS STEP-DOWN REGULATOR
HZ
N/A
LTC3621EMS8E
DEMO CIRCUIT 1863A
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
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
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Thursday, June 13, 2013
11
17V VIN SYNCHRONOUS STEP-DOWN REGULATOR
HZ
N/A
LTC3621EMS8E
DEMO CIRCUIT 1863A
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
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
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Thursday, June 13, 2013
11
17V VIN SYNCHRONOUS STEP-DOWN REGULATOR
HZ
N/A
LTC3621EMS8E
DEMO CIRCUIT 1863A
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
TOM G.PRODUCTION2 11-29-12
__
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
TOM G.PRODUCTION2 11-29-12
__
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
TOM G.PRODUCTION2 11-29-12
__
E3E3
E2E2
JP3JP3
E4E4
R7
84.5k
R7
84.5k
JP6JP6
CFF
22pF
CFF
22pF
R3
619k
R3
619k
E8E8
Rset
619k
Rset
619k
C4
1uF
C4
1uF
R1
100k
OPT
R1
100k
OPT
C3
22uF
C3
22uF
L1
4.7uH
L1
4.7uH
+
C1A
8.2uF
25V
+
C1A
8.2uF
25V
E5E5
E7E7
R5
196k
R5
196k
JP5JP5
R8
OPT
R8
OPT
U1 LTC3621EMS8E
U1 LTC3621EMS8E
SW 1
VIN
2
RUN
3
FB 5
INTVCC
6
MODE/SYNC
7
GND
9
PGOOD
4
SGND
8
JP2JP2
1
2
3
E6E6
R6
137k
R6
137k
E1E1
R2
100k
OPT
R2
100k
OPT
C1
10uF
C1
10uF
JP8JP8
Rpgood
100k
Rpgood
100k
JP7JP7
C2
22uF
C2
22uF
R4
309k
R4
309k
JP1JP1
1
2
3
JP4JP4
8
dc1863af
DEMO MANUAL DC1863A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2013
LT 1013 • PRINTED IN USA
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
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
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
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
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 applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
