DC1909A - Demo Manual

DEMO MANUAL DC1909A
LT3840
60V Current Mode Step-Down
DC/DC Converter with
Accurate Current Limit
Description
Demonstration circuit 1909A is a 150kHz, 60V currentmode DC/DC step-down converter with accurate current
limit featuring the LT®3840.
The circuit operates from a VIN range of 4.5V to 60V, survives an 80V transient, and outputs 3.3V at 20A (66W).
An integrated buck-boost switching regulator generates
a 7.5V bias supply voltage for MOSFET gate drive and IC
power to increase the overall efficiency by reducing the
power loss. A soft-start feature controls the output voltage
slew rate at start-up, reducing current surges and voltage
overshoots. The modes of operation (Burst Mode®, discontinuous current mode and continuous current mode)
are jumper selectable. Both Burst Mode operation and
discontinuous current mode increase the efficiency at light
Performance Summary
loads. Continuous current mode will maintain a constant
switching frequency regardless of the load current.
The average current control loop regulates the maximum
output current of the switching regulator. An Optional
LDO circuit is provided on the bottom side of the board
for programming the LT3840 current limit set point.
This board is suitable for a wide range of automotive,
telecom, industrial, and other applications.
The LT3840 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this demo manual
for DC1909A.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Specifications are at TA = 25°C
SYMBOL
PARAMETER
CONDITIONS
MIN
IOUT = 0A to 20A
3.168
TYP
MAX
VIN
Input Voltage Range
VOUT
Output Voltage
60
V
3.3
3.432
V
IOUT
Maximum Output Current
fSW
Switching Frequency
150
20
21.2
kHz
VOUT(P-P)
Output Ripple
50
mV
VREG
Output Regulation
Line and Load (4.5VIN to 60VIN, 0AOUT to 20AOUT)
0.15
%
POUT/PIN
Efficiency (See Figure 3)
VIN = 12V, IOUT = 20A
VIN = 24V, IOUT = 20A
91.3
90.5
%
%
4.5
18.8
UNITS
A
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DEMO MANUAL DC1909A
Quick Start Procedure
DC1909A is easy to set up to evaluate the performance
of the LT3840. Refer to Figure 1 for proper measurement
equipment setup and follow the procedure below:
NOTE: When measuring the input or output voltage ripple,
care must be taken to avoid a long ground lead on the
oscilloscope probe. See Figure 2 for the proper scope
technique.
1.Set an input power supply that is capable of 60V/20A.
Then turn off the supply.
2.With power off, connect the supply to the input terminals
VIN and GND.
a.Make the ENABLE jumper is in the EN position.
b.Input voltages lower than 4.5V can keep the converter
from turning on due to the undervoltage lockout
feature of the LTC3840.
c.If efficiency measurements are desired, an ammeter
capable of measuring 20A DC or a resistor shunt
can be put in series with the input supply in order
to measure the DC1909A’s input current.
d.A voltmeter with a capability of measuring at least
60V can be placed across the input terminals in order
to get an accurate input voltage measurement.
3.Turn on the power at the input.
NOTE: Make sure that the input voltage never exceeds 80V.
4.Check for the proper output voltage of 3.3V. Turn off
the power at the input.
5.Once the proper output voltage is established, connect
a variable load capable of sinking 20A at 3.3V to the
output terminals VOUT and GND. Set the current for 0A.
a.If efficiency measurements are desired, an ammeter
or a resistor shunt that is capable of handling 20ADC
can be put in series with the output load in order to
measure the DC1909A’s output current.
b.A voltmeter with a capability of measuring at least
3.3V can be placed across the output terminals in
order to get an accurate output voltage measurement.
6.Turn on the power at the input.
NOTE: If there is no output, temporarily disconnect the
load to make sure that the load is not set too high.
7.Once the proper output voltage is again established,
adjust the load and/or input within the operating range
and observe the output voltage regulation, ripple voltage, efficiency and other desired parameters.
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DEMO MANUAL DC1909A
Quick Start Procedure
Figure 1. Proper Measurement Equipment Setup
+
VOUT
–
COUT
GND
Figure 2. Measuring Output Ripple
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DEMO MANUAL DC1909A
Quick Start Procedure
95
EFFICIENCY (%)
90
85
80
75
VIN = 12V
VIN = 24V
0
4
12
8
IOUT (A)
16
20
DC1909a F03
Figure 3. DC1909A Pulse-Skipping Mode Efficiency
IOUT 5A/DIV
VOUT 100mV/DIV
200µs/DIV
DC1909a F04
Figure 4. DC1909A 9.5A to 19.5A Load Transient
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DEMO MANUAL DC1909A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Cap., SMT Alum 56µF 63V 25%
Sun Elect.Ind. 63HVH56M
Required Circuit Components
1
2
CIN1, CIN2
2
1
CIN3
Cap., X7S 0.22µF 100V 10% 0805
TDK C2012X7S2A224KT
3
6
CIN4 to CIN9
Cap., X7R 2.2µF 100V 20% 1210
Taiyo Yuden HMK325B7225MN-T
4
2
COUT1, COUT2
Cap., X5R 22µF 6.3V 20% 0805
TDK C2012X5R0J226M
5
2
COUT5, COUT6
Cap., POSCAP 680µF 6.3V ±20% D4
Panasonic 6TPE680MI
6
2
C1, C4
Cap., X7R 1µF 16V 10% 0603
TDK C1608X7R1C105K
7
1
C2
Cap., X5R 4.7µF 16V 20% 0603
TDK C1608X5R1C475MT
8
1
C3
Cap., X7R 0.47µF 100V 10% 1206
TDK C3216X7R2A474K
9
2
C6, C13
Cap., X7R 10nF 16V 20% 0402
AVX 0402YC103MAT2A
10
1
C8
Cap., NPO 100pF 25V 10% 0402
AVX 04023A101KAT2A
11
2
C10, C12
Cap., X7R 2.2nF 25V 20% 0402
AVX 04023C222MAT2A
12
1
C11
Cap., NPO 1nF 25V 10% 0402
AVX 04023A102KAT2A
13
1
C16
Cap., X7R 1µF 100V 15% 1206
Murata GRM31CR72A105KA01L
14
1
D1
Fast Switching Diode SOD-323
Diodes Inc. 1N4448HWS
15
1
D2
Schottky Diode 5A PowerDi5
Diodes Inc. PDS5100H
16
1
L1
Inductor, 33µH
Coilcraft ME3320-333KL
17
1
L2
Inductor, 2.2µH
COOPERBussmann HC2LP-2R2-R
18
2
Q1, Q2
MOSFET, N-Channel, 80V PG-TDSON-8
Infineon BSC123N08NS3
19
2
Q3, Q4
MOSFET, N-Channel, 75V/100A SuperSO8
Infineon BSC042NE7NS3
20
1
RSNS1
Res., 0.0025 1W 1% 2512
Vishay WSL25122L500FEA
21
5
R2, R7, R19, R20, R22
Res., Chip 0Ω 1/16W 1A 0402
Vishay CRCW04020000Z0ED
22
1
R3
Res., Chip 1M 0.06W 5% 0402
Vishay CRCW04021M00JNED
23
2
R6, R8
Res., Chip 12 0.06W 5% 0402
Vishay CRCW040212R0JNED
24
2
R9, R14
Res., Chip 100k 0.06W 5% 0402
Vishay CRCW0402100KJNED
25
1
R10
Res., Chip 825k 0.06W 1% 0402
Vishay CRCW0402825KFKED
26
1
R11
Res., Chip 105k 0.06W 1% 0402
Vishay CRCW0402105KFKED
27
1
R12
Res., Chip 13.0k 0.06W 1% 0402
Vishay CRCW040213K0FKED
28
1
R13
Res., Chip 499k 0.06W 1% 0402
Vishay CRCW0402499KFKED
29
1
R17
Res., Chip 1M 0.06W 5% 0603
Vishay CRCW06031M00JNEA
30
1
R21
Res., Chip 1k 0.06W 5% 0402
Vishay CRCW04021K00JNED
31
1
U1
I.C., LT3840EFE TSSOP28
Linear Technology Corporation LT3840EFE#PBF
Additional Circuits
1
0
CIN10, CIN11, CIN12 (Opt)
Cap., 1210
2
0
COUT3, COUT4 (Opt)
Cap., 0805
3
0
COUT7 (Opt)
Cap., 0603
4
0
C5 (Opt)
Cap., 1206
5
0
C7, C9, C17 (Opt)
Cap., 0402
6
0
C14 (Opt)
Cap., X7R 1µF 16V 20% 0805
Taiyo Yuden EMK212BJ105MG
7
0
C15 (Opt)
Cap., X7R 1µF 10V 10% 0603
Taiyo Yuden LMK107BJ105KA
8
0
R4 (Opt)
Res., 1206
9
0
R5 (Opt)
Res., 0402
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DEMO MANUAL DC1909A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
10
11
0
R15 (Opt)
Res., Chip 3.74M 0.06W 1% 0603
Vishay CRCW06033M74FKEA
0
R16, R18 (Opt)
Res., 0603
12
0
U2 (Opt)
I.C., LDO Linear Reg. SC70-SC8
Linear Technology Corporation LT3009ESC8-5#PBF
Hardware, For Demo Board Only:
1
11
E1, E2, E5, E6, E7, E8, E9, E10, Turret, Testpoint
E11, E12, E13
Mill Max 2501-2-00-80-00-00-07-0
2
2
E3, E4
Turret, Testpoint
Mill Max 2308-2-00-80-00-00-07-0
3
1
JP1
Headers, 3 Pins 2mm Ctrs.
Sullins NRPN031PAEN-RC
4
1
JP2
Headers, Dbl. Row 2 × 3 2mm Ctrs.
Sullins NRPN032PAEN-RC
5
6
J1, J2, J3, J4, J5, J6
Connector, Banana Jack
Keystone 575-4
6
2
XJP1, XJP2
Shunt, 2mm Ctrs.
Samtec 2SN-BK-G
7
4
MH1 to MH4
STANDOFF, NYLON, 0.5"
KEYSTONE, 8833 (SNAP ON)
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6
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.
A
B
C
VIN_S
GND
GND
IMON
ICTRL
GND
GND
TK/SS
SYNC
PG
E2
J2
J1
1
E13
E12
E11
E10
E9
E8
E7
E6
E5
JP1
3
2
ENABLE
DIS
EN
GND_S
GND
VIN
4V TO 60V
80V TRANSIENT
E1
5
ICTRL
R14
100k
R9
100k
VOUT
R17
1M
0603
4
6
3
5
JP2
2
1
MODE
R7
0 Ohm
R5
(Opt)
R3
1M
INTVCC
FB
63V
R18
(Opt)
0603
CIN2
63V
+ 56礔
CIN1
+ 56礔
BURST
C8
100pF
C10
2.2nF
R12
13.0k
1%
C13
10nF
6
8
5
10
4
9
11
12
13
3
14
4
28
1礔
16V
0603
C11
1nF
R21
1k
AUXSW1
1
18
C17
(Opt)
17
ICTRL
C12
2.2nF
29
GND
R22
0 Ohm
16
IMON
GND
FB
SENSE-
SENSE+
BGRTN
BG
SW
TG
BOOST
PGND
INTVCC
AUXSW2
27
L1
33礖
ME3320-333KL
U1
LT3840EFE#PBF
ICOMP
TK/SS
VC
RT
MODE
SYNC
PG
OVLO
UVLO
EN
AUXVIN
VIN
AUXBST
NOTE: UNLESS OTHERWISE SPECIFIED.
1. ALL RESISTORS 0402.
2. ALL CAPACITORS 0402.
CONT
PULSE SKIP
R11
105k
1%
(150kHz)
1206
1uF 100V
C16
0.47uF
100V
1206
C3
C1
15
7
20
19
24
25
21
22
23
2
26
C7
(Opt)
C6
10nF
3
C4
12
R6
(Opt)
C9
825k
1%
R10
BSC042NE7NS3
1礔
16V
0603
Q3
Q1
BSC123N08NS3
D1
1N4448HWS
R13
499k
1%
12
R8
0 Ohm
R20
R19 0 Ohm
R2
C2
4.7礔
16V
0603
0 Ohm
FB
INTVCC
3
Q4
BSC042NE7NS3
C5
(Opt)
1206
R4
(Opt)
1206
Q2
BSC123N08NS3
CIN3
0.22uF
100V
0805
CIN5
2.2uF
100V
1210
2
CIN6
2.2uF
100V
1210
D2
PDS5100H
2
0.0025
1%
1W
2512
L2
2.2礖
HC2LP-2R2-R
COOPERBussmann
RSNS1
CIN4
2.2uF
100V
1210
2
D
4
3
1
5
COUT1
22uF
6.3V
0805
CIN8
2.2uF
100V
1210
C14
1uF
16V
0805
INTVCC
CIN7
2.2uF
100V
1210
1
5
CIN10
(Opt)
1210
ADJ
OUT
2
3
4
GND GND GND
SHDN
IN
7
6
U2
LT3009ESC8-5#PBF
VOUT
COUT4 COUT5 COUT6
(Opt) + 680礔 + 680礔
6.3V
6.3V
0805
CIN12
(Opt)
1210
COUT3
(Opt)
0805
CIN11
(Opt)
1210
C15
1uF
10V
0603
5V
R16
TBD
0603
1
R15
3.74M
1%
0603 ICTRL
OPTIONAL CIRCUIT
COUT2
22uF
6.3V
0805
CIN9
2.2uF
100V
1210
1
E4
J6
J5
GND_S
GND
VOUT
3.3V / 20A
VOUT_S
COUT7
0603
J4
J3
E3
A
B
C
D
DEMO MANUAL DC1909A
Schematic Diagram
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DEMO MANUAL DC1909A
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 application engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
dc1909af
8
Linear Technology Corporation
LT 0614 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2014
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