1
dc1640af
DEMO MANUAL DC1640A
DESCRIPTION
LTC3833EUDC High
Efficiency Step-Down
DC/DC Converter
Demonstration circuit 1640A is a 1.5V/20A synchronous
buck converter operating with a switching frequency of
300kHz over an input voltage range of 4.5V to 14V. The
demo board comes in two versions. The A version uses
inductor DCR current sensing with an iron powder inductor
for high efficiency. The B version uses a 2mΩ /1% sense
resistor for accurate current sensing with a low DCR ferrite
inductor. The fixed on-time valley current mode topology
of the LTC3833 allows for a fast load step response (see
Figures 4 and 5). The load step response can be tested with
the onboard load step circuit and a bench pulse generator.
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.
PARAMETER CONDITION VALUE
Minimum Input Voltage 4.5V
Maximum Input Voltage 14V
Output Voltage IOUT = 0A to 20A 1.5V ±2%
Switching Frequency 300kHz
Efficiency
DCR Sense Version (A)
RSENSE Version (B)
VIN = 12V, VOUT = 1.5V, IOUT = 20A; See Figures 2 and 3
89.4%
88.8%
PERFORMANCE SUMMARY
Other features of the board include a MODE jumper to
program either DCM or CCM with light or no load, a PLLIN
input for synchronizing the converter to an external clock,
a TRACK/SS pin, a PGOOD pin and an EXTVCC pin.
The demo board uses a high density, two sided drop-in
layout. The entire converter, excluding the bulk output and
input capacitors, fits within a compact 1.4” × 0.6” area on
the board. The package style for the LTC3833EUDC is a
3mm × 4mm 20-lead QFN with an exposed ground pad.
Design files for this circuit board are available at
http://www.linear.com/demo
(TA = 0°C to 85°C)
2
dc1640af
DEMO MANUAL DC1640A
LOAD
+
–
A
IOUT
A
IIN
VIN
SUPPLY
*
+
+
–
V
VOUT
+– V
VIN THE VO_SNS+ and VO_SNS– TURRETS MONITOR VOLTAGE ACROSS COUT4 WHICH
IS THE POINT OF REGULATION. MONITOR THE VOLTAGE ACROSS COUT2 FOR MORE
ACCURATE EFFICIENCY MEASUREMENTS.
DC1640 F01
*
QUICK START PROCEDURE
Demonstration circuit 1640A is easy to set up to evaluate
the performance of the LTC3833EUDC. Please refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below.
1. With power off, connect the input supply, load and
meters as shown in Figure 1. Preset the load to 0A
and VIN supply to be 0V. Place jumpers in the following
positions:
JP1 JP2
RUN MODE
ON CCM
2. Adjust the input voltage to be between 4.5V to 14V.
VOUT should 1.5V ± 2%.
3. Next, apply 20A load and recheck VOUT.
4. Once the DC regulation is confirmed, observe the output
voltage ripple, load step response, efficiency and other
parameters.
Note 1. To measure the output voltage ripple, use the BNC
connector labeled VOUT.
Note 2. Do not apply the load from the VO_SNS+ turret
to the VO_SNS– turret. This will damage the converter.
These turrets are only intended to monitor VOUT across
COUT4 which is the point of regulation.
Figure 1. Proper Measurement Equipment Setup
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dc1640af
DEMO MANUAL DC1640A
QUICK START PROCEDURE
Demonstration circuit 1640A has a simple load step circuit
consisting of a MOSFET and sense resistor. To apply a load
step, follow the steps below.
1. Preset the amplitude of a pulse generator to 0.0V and
the duty cycle to 5% or less.
2. Connect the VOUT and LOAD STEP BNC connectors to
the oscilloscope. Use a short cable to minimize noise
pickup.
3. Connect the output of the pulse generator to the PULSE
GEN turret and connect the return to the GND turret.
4. With the converter running, slowly increase the ampli-
tude of the pulse generator output to provide the desired
load step pulse height. The scaling for the LOAD STEP
signal is 10mV/Amp.
Figure 2. Efficiency Curves for the DC1640A in CCM. Figure 3. Efficiency Curves for the DC1640A in CCM and DCM.
LOAD CURRENT (A)
0
70
EFFICIENCY (%)
75
80
85
95
510 15 20
DC1640 F02
25
90
QTOP = RENESAS RJK0305DPB
QBOTTOM = RENESAS RJK0330DPB
DCR SENSE VERSION (–A):
L = WÜRTH 744355047
(0.47µH, DCR = 0.9mΩ ±10%)
RSENSE VERSION (–B):
L = COILTRONICS FP1308R3-R44
(0.44µH, DCR = 0.18mΩ ±20%)
RSENSE = 2mΩ
DCR SENSE
RSENSE
LOAD CURRENT (A)
0.01
0
EFFICIENCY (%)
70
100
10.1 10 100
DC1640 F03
60
50
40
30
20
10
90
80
QTOP = RENESAS RJK0305DPB
QBOTTOM = RENESAS RJK0330DPB
DCR SENSE VERSION (–A):
L = WÜRTH 744355047
(0.47µH, DCR = 0.9mΩ ±10%)
RSENSE VERSION (–B):
L = COILTRONICS FP1308R3-R44
(0.44µH, DCR = 0.18mΩ ±20%)
RSENSE = 2mΩ
RSENSE DCM
RSENSE CCM
DCR SENSE DCM
DCR SENSE CCM
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dc1640af
DEMO MANUAL DC1640A
QUICK START PROCEDURE
Figure 4. 10A to 20A to 10A Load Step Response of the
DC1640A-A (DCR Sense) at VIN = 12V. COUT = 2x Sanyo
2R5TPE330M9 || 2x 100µF, X5R, 6.3V, 1206; L = 0.47µH;
FSW = 300kHz
Figure 5. 10A to 20A to 10A Load Step Response of the
DC1640A-B (RSENSE) at VIN = 12V. COUT = 2x Sanyo
2R5TPE330M9 || 2x 100µF, X5R, 6.3V, 1206; FSW = 300kHz;
L = 0.44µH
DC1640 F04
LOAD STEP
10A/DIV 10A
20A
1.5VO (AC)
50mV/DIV
50µs/DIV
DC1640 F05
LOAD STEP
10A/DIV 10A
20A
1.5VO (AC)
50mV/DIV
50µs/DIV
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dc1640af
DEMO MANUAL DC1640A
PARTS LIST
DEMO CIRCUIT 1640A-A (DCR SENSE)
ITEM QUANTITY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C1 Cap X7R 0.22µF 16V 10% 0603 AVX 0603YC224KAT2A
2 2 C3, C9 Cap X7R 0.1µF 16V 10% 0603 AVX 0603YC104KAT2A
3 1 C4 Cap X7R 0.01µF 16V 10% 0603 AVX 0603YC103KAT2A
4 1 C5 Cap C0G 100pF 50V 5% 0603 AVX 06035A101JAT2A
5 1 C6 Cap C0G 470pF 50V 10% 0603 AVX 06035A471KAT2A
6 1 C7 Cap X5R 4.7µF 16V 10% 0805 AVX 0805YD475KAT2A
7 3 CIN1, CIN2, CIN6 Cap X5R 22µF16V 10% 1210 Murata GRM32ER61C226KE20L
8 1 CIN4 Cap SVP 180µF 16V 30mΩ ESR Sanyo 16SVP180MX
9 2 COUT1, COUT2 Cap X5R 100µF 6.3V 20% 1206 Murata GRM31CR60J107ME39L
10 2 COUT3, COUT4 Cap POSCAP 330µF 2.5V 20% 7343 Sanyo 2R5TPE330M9
11 1 D1 Diode Schottky 30V SOD323 Central Semi CMDSH-3TR
12 1 L1 Inductor 0.47µH Würth Elektronik 744355047
13 1 Q1 MOSFET Power N-CH LFPAK Renesas RJK0305DPB
14 1 Q2 MOSFET Power N-CH LFPAK Renesas RJK0330DPB
15 1 R1 Res 100k 1/16W 5% 0603 Yageo RC0603JR-07100KL
16 2 R10, R11 Res 10 1/16W 5% 0603 Yageo RC0603JR-0710RL
17 2 R13, R17 Res 0 1/16W 0603 Yageo RC0603FR-070RL
18 1 R15 Res 13k 1/16W 1% 0603 Yageo RC0603FR-0713KL
19 1 R18 Res 137k 1/16W 1% 0603 Yageo RC0603FR-07137KL
20 1 R20 Res 2.2 1/16W 5% 0603 Yageo RC0603JR-072R2L
21 2 R21, R8 Res 10k 1/16W 1% 0603 Yageo RC0603FR-0710KL
22 2 R4, R9 Res 0 1/16W 0603 Yageo RC0603FR-070RL
23 1 R6 Res 15k 1/10W 1% 0603 Yageo RC0603FR-0715KL
24 1 R7 Res 2.15k 1/16W 1% 0603 Yageo RC0603FR-072K15L
25 1 RS1 Res 0.000 2512 Tepro RN5326
26 1 U1 IC LTC3833EUDC Linear Technology LTC3833EUDC#PBF
Additional Circuit Components
1 0 C2, C8, C10 Cap 0603 OPT
2 0 CIN3 Cap SVP-F8 OPT
3 0 CIN5 Cap 1210 OPT
4 0 COUT5, COUT6 Cap 1206 OPT
5 0 Q3, Q4 MOSFET Power N-CH LFPAK OPT
6 1 Q5 MOSFET N-CH 30-V (D-S) DPAK-TO252AA Vishay SUD50N03-12P-E3
7 1 R22 Res Chip 10k 1/16W 1% 0603 Yageo RC0603FR-0710KL
8 1 R23 Res 0.01 2% 2010 IRC LRC-LRF2010LF-01-R010-G
9 0 R2, R3, R12, R14, R5, R16, R19 Res 0603 OPT
Hardware for Demo Board Only
1 10 E1 to E10 Testpoint Turret .094” Mill-Max 2501-2-00-80-00-00-07-0
2 4 J1, J2, J3, J4 Jack Banana Keystone 575-4
3 2 J5, J6 Conn BNC 5 Pins Connex 112404
4 2 JP1, JP2 Shunt 2MM Center Samtec 2SN-BK-G
5 2 JP1, JP2 Header 2MM Single Row 3 Pin Samtec TMM-103-02-L-S
6 4 Stand-Off Nylon 0.50” Keystone 8833 (Snap-On)
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dc1640af
DEMO MANUAL DC1640A
PARTS LIST
DEMO CIRCUIT 1640A-B (RSENSE)
ITEM QUANTITY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C1 Cap X7R 1000pF 50V 5% 0603 AVX 06035C102JAT2A
2 2 C3, C9 Cap X7R 0.1µF 16V 10% 0603 AVX 0603YC104KAT2A
3 1 C4 Cap X7R 0.01µF 16V 10% 0603 AVX 0603YC103KAT2A
4 1 C5 Cap C0G 100pF 50V 5% 0603 AVX 06035A101JAT2A
5 1 C6 Cap C0G 470pF 50V 10% 0603 AVX 06035A471KAT2A
6 1 C7 Cap X5R 4.7µF 16V 10% 0805 AVX 0805YD475KAT2A
7 3 CIN1, CIN2, CIN6 Cap X5R 22µF16V 10% 1210 Murata GRM32ER61C226KE20L
8 1 CIN4 Cap SVP 180µF 16V 30mΩ ESR Sanyo 16SVP180MX
9 2 COUT1, COUT2 Cap X5R 100µF 6.3V 20% 1206 Murata GRM31CR60J107ME39L
10 2 COUT3, COUT4 Cap Poscap 330µF 2.5V 20% 7343 Sanyo 2R5TPE330M9
11 1 D1 Diode Schottky 30V SOD323 Central Semi CMDSH-3TR
12 1 L1 Inductor 0.44µH Cooper Bussmann FP1308R3-R44-R
13 1 Q1 MOSFET Power N-CH LFPAK Renesas RJK0305DPB
14 1 Q2 MOSFET Power N-CH LFPAK Renesas RJK0330DPB
15 1 R1 Res Chip 100k 1/16W 5% 0603 Yageo RC0603JR-07100KL
16 2 R10, R11 Res Chip 10 1/16W 5% 0603 Yageo RC0603JR-0710RL
17 1 R14 Res Chip 0 1/16W 0603 Yageo RC0603FR-070RL
18 1 R15 Res Chip 16.5k 1/16W 1% 0603 Yageo RC0603FR-0716K5L
19 1 R18 Res Chip 137k 1/16W 1% 0603 Yageo RC0603FR-07137KL
20 2 R2, R3 Res Chip 10 1/10W 1% 0603 Yageo RC0603FR-0710RL
21 1 R20 Res Chip 2.2 1/16W 5% 0603 Yageo RC0603JR-072R2L
22 2 R21, R8 Res Chip 10k 1/16W 1% 0603 Yageo RC0603FR-0710KL
23 2 R4, R9 Res Chip 0 1/16W 0603 Yageo RC0603FR-070RL
24 1 R6 Res Chip 15k 1/10W 1% 0603 Yageo RC0603FR-0715KL
25 1 RS1 Res Chip 0.002Ω 1W 1% 2512 Vishay WSL25122L000FEA
26 1 U1 IC LTC3833EUDC Linear Technology LTC3833EUDC#PBF
Additional Circuit Components
1 0 C2, C8, C10 Cap 0603 OPT
2 0 CIN3 Cap SVP-F8 OPT
3 0 CIN5 Cap 1210 OPT
4 0 COUT5, COUT6 Cap 1206 OPT
5 0 Q3, Q4 MOSFET Power N-CH LFPAK OPT
6 1 Q5 MOSFET N-CH 30-V (D-S) DPAK-TO252AA Vishay SUD50N03-12P-E3
7 1 R22 Res Chip 10k 1/16W 1% 0603 Yageo RC0603FR-0710KL
8 1 R23 Res 0.01 2% 2010 IRC LRC-LRF2010LF-01-R010-G
9 0 R2, R3, R12, R14, R5, R16, R19 Res 0603 OPT
Hardware for Demo Board Only
1 10 E1 to E10 Testpoint Turret .094” Mill-Max 2501-2-00-80-00-00-07-0
2 4 J1, J2, J3, J4 Jack Banana Keystone 575-4
3 2 J5, J6 Conn BNC 5 Pins Connex 112404
4 2 JP1, JP2 Shunt 2MM Center Samtec 2SN-BK-G
5 2 JP1, JP2 Header 2MM Single Row 3 Pin Samtec TMM-103-02-L-S
6 4 Stand-Off Nylon 0.50” Keystone 8833 (Snap-On)
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dc1640af
DEMO MANUAL DC1640A
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 representation
that the interconnection of its circuits as described herein will not infringe on existing patent rights.
SCHEMATIC DIAGRAM
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
AA
B B
CC
DD
VIN-
VIN
GND
1.5V / 20A
4.5V - 14V
GND
VOUT
2512
VIN+
1210 1210
1206
DCR SENSE
FILTER /
DIVIDER
MODE
CCM
DCM
PLLIN
RUN
VO_SNS-
VO_SNS+
FSW = 300kHz
1206
LOAD STEP CIRCUIT
2010
PULSE GEN
GND
5% DUTY CYCLE MAX
LOAD STEP
10mV / A
VOUT
NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS ARE IN OHMS, 0603.
2. INSTALL SHUNTS ON JUMPERS AS SHOWN.
ALL CAPACITORS ARE IN MICROFARADS, 0603.
1210 1210
ONLY APPLY LOAD
FROM J3 TO J4
7343 7343
SVP-F8
ON
OFF
0.002 Ohm 2512, VISHAY WSL25122L000FEA
0.000 Ohm 2512, TEPRO RN5326
RS1
R13
0
OPT 10
OPT
R2,R3R12
OPT
OPT
R7
*
2.15K
-A (DCR SENSE)
COILTRONICS FP1308R3-R44-R (0.44uH) OPT
C1
0.22uF
WURTH 744355047 (0.47uH)
L1
1000pF-B (RSENSE)
ASSY
OPT
OPT
0
0
R14R17R15
13.0K
16.5K
MIKE S.
PRODUCTION FAB 01/72/92-
REVISION HISTORY
ETADNOITPIRCSED APPROVEDECO REV
2
DEMO CIRCUIT 1640A-A/B
11
HIGH EFFICIENCY STEP-DOWN DC-DC CONVERTER
N/A
LTC3833EUDC
NC
MIKE S.
9/27/10
SIZE
DATE:
.VER.ON CI
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
S+
S-
VIN
INTVCC
INTVCC
S- S+
VOUT
VOUT
INTVCC
VIN
VOUT
R2
*
E9
R3
*
J4
C7
4.7uF
16V
0805
Q1
RJK0305DPB
4
5
3
1
2
C4
0.01uF
Q5SUD50N03-12P
3
1
2
CIN1
22uF
16V
R7
*
Q2
RJK0330DPB
4
5
3
1
2
R15
*
R16
OPT
E4
PGOODC1
*
R22
10K
CIN2
22uF
16V
R6
15K
J3
L1
*
R4
0R10
10
U1
LTC3833EUDC
1
2
3
4
6
7
11
12
13
15
8
9
10
14
16
17
18
19
20
21
5
VOSNS-
VOSNS+
TRKSS
ITH
RT
RUN
INTVCC
PGND
BG
TG
EXTVCC
MODE/PLLIN
VIN
SW
BOOST
PGOOD
SNS+
SNS-
VOUT
SGND
VRNG
+
COUT4
330uF
2.5V
R1
100K
C5
100pF
R20
2.2
JP1
1
3
2
COUT1
100uF
6.3V
E7
EXTVCC
+
COUT3
330uF
2.5V
COUT5
OPT
1206
D1
CMDSH-3
E8
E2
+
CIN4
180uF
16V
R14
*
Q3
OPT
4
5
3
1
2
R8
10K
COUT6
OPT
1206
C10
OPT
RS1
*
R19
OPT
E6
C9
0.1uF
16V
R23
0.01
CIN5
OPT
J1
C6
470pF
E10
JP2
1
3
2
+
CIN3
OPT
J6
1
2
3
4
5
COUT2
100uF
6.3V
R11
10
J2
C3
0.1uF
16V
E1
R9
0
Q4
OPT
4
5
3
1
2
E3
R17
*
R13
*
R12
*
CIN6
22uF
16V
R5
OPT
E5
TRK/SS
J5
1
2
3
4
5
R21
10K
R18
137K
C2
OPT
C8
OPT
8
dc1640af
DEMO MANUAL DC1640A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 2010
LT 1210 • 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 direc-
tive 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
