DC1619A Demo Manual Datasheet by Analog Devices Inc.

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l ’ LI” DEMO MANUAL DC1619A TECHNOLOGY L7 LJUW
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DEMO MANUAL DC1619A
DESCRIPTION
LT3845A: High Voltage
Synchronous Buck Controller
with Programmable
Frequency and Sync
Demonstration Circuit 1619A is a 100kHz to 500kHz
programmable frequency, high voltage, current mode
DC/DC step-down converter featuring the LT
®
3845A. The
operating frequency can be synchronized up to 600kHz.
This demo board is designed for 12V up to 10A (120W)
output from a 16V to 60V input. 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 loads. Continuous current mode will
maintain a constant switching frequency regardless of
the load current.
An optional boost bias circuit is provided on the bottom
side of the board for back-driving the LT3845A internal
regulator from the output voltage. Customers may want
to use this optional circuit with modified applications
that have relatively high input voltages and low (~3.3V)
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
PERFORMANCE SUMMARY
output voltages. In such applications, this optional circuit
can increase the overall efficiency by reducing the power
loss in the LT3845A. The demonstration board has the
option of doubling the number of switching MOSFETs to
facilitate higher output current. This board is suitable for
a wide range of industrial control systems and telecom
power supplies.
The LT3845A data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for demo circuit 1619A.
Note: It is best to ground the SYNC pin if the SYNC func-
tion is not being used.
Design files for this circuit board are available at
http://www.linear.com/demo
(TA = 25°C)
PARAMETER FOR BUCK REGULATOR CONDITION VALUE
Minimum Input Voltage 16V
Maximum Input Voltage 60V
Output Voltage, VOUT 12V ±2%
Maximum Output Current VIN < 28V
VIN ≥ 28V
7.5A to 10A (See Figure 5)
10A
Typical Switching Frequency R9 = 49.9k 300kHz
External Clock Synchronous Frequency Range R9 = 49.9k 325kHz to 600kHz
Efficiency VIN = 48V, VOUT = 12V, IOUT = 8A 94% (See Figure 3)
LT3845AEFE HIGH VOLTAGE SYNCHRONOUS BUCK ‘ m CONTROLLER WITH ADJUSTABLE opzmmc FREQUENCY m . DEMO CIRCUIT 1619A y'l'cwn ODD Elia-1m . an "”304 v.mn 5m mt m ME Igfirs'ésw- m. 7mulmm . .‘fl 'aunsv I, W. (ma) )mwon ; mu m "I. linear cam
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DEMO MANUAL DC1619A
QUICK START PROCEDURE
Figure 1. Proper Measurement Equipment Setup
Demonstration circuit 1619A is easy to set up to evaluate
the performance of the LT3845A. 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. Measure the input or output volt-
age ripple directly across the VIN or VOUT capacitors by
soldering leads on the appropriate capacitor. See Figure 2
for proper scope probe technique. An oscilloscope probe
can be directly connected to VIN or VOUT using a banana
jack to BNC adaptors.
1. Place JP1 in the RUN position.
2. Place JP2 in the desired operating mode: burst, pulse-
skipping or continuous.
3. With power off, connect the input power supply to VIN
and GND.
4. Turn on the power at the input and adjust the input
voltage until the LT3845A turns on.
Note: Make sure that the input voltage does not ex-
ceed60V.
5. Check for the proper output voltage.
Note: If output does not come up, make sure the load
is not set too high. Reduce the load and repeat steps
4 and5.
6. Once the proper output voltage is established, adjust the
input voltage and load within the operating range and
observe the output voltage regulation, ripple voltage,
efficiency and other parameters.
7. An external clock can be added to the SYNC pin when
the SYNC function is used. See the Oscillator SYNC
section in the data sheet for details.
V
+
–
A
–+
V
+
–
A
–+
0V TO 60V
7.5A
+
–
LOAD
0A TO 10A
+
–
DC1619 F01
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DEMO MANUAL DC1619A
QUICK START PROCEDURE
INPUT OR OUTPUT CAPACITOR
WIRE
Figure 2. Measuring Input or Output Ripple
Figure 3. DC1619A Burst Mode Efficiency
IOUT (A)
0
EFFICIENCY (%)
80
90
100
8
DC1619A F03
70
60
75
85
95
65
55
50 21 43 67 9
510
16VIN
20VIN
24VIN
36VIN
48VIN
60VIN
.s’ L7Hfl§fl§
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DEMO MANUAL DC1619A
QUICK START PROCEDURE
Figure 4. DC1619A 2A to 8A Load Transient
Figure 5. DC1619A Output Current Derating Graph
VIN (V)
16 20 24
7.5
IOUT(MAX) (A)
8.0
8.5
9.0
9.5
10.0
28 32 36 40 44 48 52 56
DC1619A F05
60
10.5
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DEMO MANUAL DC1619A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 2 CIN1, CIN2 CAP., SMT Aluminum, 33μF, 63V SUNCON, 63HVH33M
2 2 CIN3, CIN4 CAP., X7R, 2.2μF, 100V, 10%, 1210 MURATA,GRM32ER72A225KA35L
3 1 COUT1 CAP., POSCAP, 68μF, 16V, 20%, SANYO, 16TQC68M
4 1 COUT3 CAP., X5R, 22μF, 16V, 10%, 1210 TAIYO, EMK325BJ226KM-T
5 1 C1 CAP., X5R, 0.47μF, 100V, 10%, 1206 TDK, C3216X5R2A474KAT
6 2 C2, C5 CAP., X7R, 1500pF, 50V, 10%, 0402 AVX, 04025C152KAT
7 1 C4 CAP., C0G, 100pF, 50V, 10%, 0402 TDK, C1005COG1H101J
8 1 C6 CAP., X5R, 0.1μF, 16V, 10%, 0402 AVX, 0402YD104KAT
9 1 C7 CAP., X5R, 1μF, 16V, 10%, 0603 TDK, C1608X5R1C105K
10 1 C9 CAP., C0G, 220pF, 100V, 10%, 1206 VISHAY, VJ1206A221XB
11 1 D1 HIGH VOLTAGE SWITCHING DIODE, SOD-523 PHILLIPS, BAS521
12 1 D2 SMT SCHOTTKY BARRIER RECTIFIER, SMB DIODES INC, B160-13-F
13 1 D3 HIGH VOLTAGE SWITCHING DIODE, SOD-323 DIODES INC, 1N4148WS-7-F
14 1 L1 INDUCTOR, 10μH WURTH ELEKTRONIC, 74435561100
15 2 Q1, Q2 N-MOSFET, 80V INFINEON, BSC123N08NS3
16 1 R1 RES., CHIP, 1M, 1/16W, 1%, 0402 VISHAY, CRCW04021M00FKED
17 1 R2 RES., CHIP, 97.6k, 1/16W, 1%, 0402 VISHAY, CRW040297K6FKED
18 1 R4 RES., CHIP, 143k, 1/16W, 1%, 0402 VISHAY, CRCW0402143KFKED
19 1 R5 RES., CHIP, 16.2k, 1/16W, 1%, 0402 VISHAY,CRCW040216K2FKED
20 1 R7 RES., CHIP, 20k, 1/16W, 1%, 0402 VISHAY, CRCW040220K0FKED
21 1 R9 RES., CHIP, 49.9k, 1/16W, 1%, 0402 VISHAY,CRCW040249K9FKED
22 1 R10 RES., CHIP, 4.99Ω, 1/16W, 1%, 0402 VISHAY,CRCW04024R99FKED
23 1 R16 RES., CHIP, 6.65Ω, 1/4W, 1%, 1206 VISHAY, CRCW12066R65FKED
24 1 R17 RES., CHIP, 0.007Ω, 1W, 1%, 2512 VISHAY, WSL25127L000FEA
25 1 U1 I.C, LT3845AEFE#PBF, TSSOP (4.4MM) 16-PIN LINEAR TECH., LT3845AEFE#PBF
Additional Demo Board Circuit Components
1 0 COUT2 (OPT) CAP., POSCAP, 68μF, 16V, 20%, SANYO, 16TQC68M
2 0 COUT4 (OPT) CAP., X5R, 22μF, 16V, 10%, 1210 AVX, 1210YD226KAT
3 0 C3, C8, C10-C13 (OPT) CAP., 0402
4 0 D4, D5 (OPT) DUAL SMT SWITCHING DIODE, SOT-23 DIODES INC, BAV99-7-F
5 1 R3 RES., CHIP, 5.1M, 1/16W, 5%, 0402 PANASONIC, ERJ2GEJ515X
6 5 R11-R15 RES., CHIP, 0Ω, 1/16W, 0402 VISHAY, CRCW04020000Z0ED
7 1 R8 RES., CHIP, 100k, 1/16W, 1%, 0402 VISHAY, CRCW0402100KFKED
8 0 Q4, Q5 (OPT) N-MOSFET, 80V INFINEON, BSC123N08NS3
9 0 Q3 (OPT) COMPLIMENARY MOSFET PAIR, SC-70 VISHAY, Si1555DL-T1-E3
10 0 R6, R18-R22 (OPT) RES., 0402
Hardware For Demo Board Only
1 4 J1-J4 JACK, BANANA KEYSTONE, 575-4
2 5 E1-E5 TESTPOINT, TURRET, 0.095" MILL-MAX, 2501-2-00-80-00-00-07-0
3 1 JP1 JMP, 3-PIN 1 ROW 0.079CC SAMTEC, TMM-103-02-L-S
4 1 JP2 2MM DOUBLE ROW HEADER 2x3 SAMTEC, TMM-103-02-L-D
5 2 JP1(1 and 2), JP2 (5 and 6) SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G
6 4 STAND-OFF STAND-OFF, NYLON 0.50" tall KEYSTONE, 8833(SNAP ON)
540— 40— wv—oiml 4h
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DEMO MANUAL DC1619A
SCHEMATIC DIAGRAM
1
1
2
2
A A
B B
CONT
BURST
PULSE SKIP
RUN
SHDN
.
NOTES:UNLESS OTHERWISE SPECIFIED
RESISTORS: OHMS, 0402
CAPACITORS: uF, 0402
* 79V CAPACITOR SURGE VOLTAGE
* L1 LAYOUT PADS ARE NON-STANDARD PADS DESIGNED TO
ACCOMMODATE THE WURTH ELEKTRONIC, 74435561100 INDUCTOR
OR THE WURTH ELEKTRONIC, 7443551151 INDUCTOR
MARTY M.PRODUCTION FAB- 2 11-15-10
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
2
DEMO CIRCUIT 1619A
12
HIGH VOLTAGE SYNCHRONOUS BUCK
N/A LT3845AEFE
NC
MARTY M.
CONTROLLER WITH ADJUSTABLE OPERATING FREQUENCY
11-15-10
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
VFB VS+
VFB
VCC VCC
VOUT
BG
VOUT
VCC
TG
VIN
SW
J2
16V - 60V
VIN
+
COUT1
68uF
16V
C3
(OPT)
R9
49.9K
J1
GND
L1
10uH*
R14 0
COUT3
22uF
16V
1210
E1
VIN
J3
GND
C8
(OPT)
U1 LT3845AEFE
5
4
3
2
116
15
14
13
6
7
8
17
12
11
9
10
VFB
BURST_EN
SS
SHDN
VIN BOOST
TG
SW
VCC
VC
SYNC
FSET
SGND
BG
PGND
SENSE-
SENSE+
C5
1500pF
J4 VOUT
12V, 120W
R4 143K
1%
C9
220pF
100V
1206
CIN3
2.2uF
100V
1210
Q2
BSC123N08N
2
4
6
1
3 5
7
8
E3
SYNC
Q1
BSC123N08N
2
4
6
1
3 5
7
8
TG
R17
0.007
2512
R3
5.1M
5%
R15 0
R1
1M
+
CIN1
33uF
63V*
C4
100pF
C1
0.47uF
100V
1206
CIN4
2.2uF
100V
1210
+
COUT2
(OPT)
R12 0
R8
100K
R11
0
R2
97.6K
D2
B160
C2
1500pF
BG
R7
20K
E2
GND
R5
16.2K
1% E5
GND
D1
BAS521
C7
1uF
16V
0603
E4
VOUT
JP2
MODE
1
5
43
6
2
R16
6.65
1206
COUT4
1210
(OPT)
R10
4.99
R13 0
D3
1N4148
R6
(OPT)
JP1
1
2
3
C6
0.1uF 16V
+
CIN2
33uF
63V*
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DEMO MANUAL DC1619A
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
1
1
2
2
A A
B B
OPTIONAL BIAS CIRCUIT OPTIONAL POWER FETS
USE OPTIONAL BIAS CIRCUIT TO BACKFEED VCC WHEN VOUT IS BETWEEN
3V AND 9V AND VCC POWER DISSIPATION EXCEEDS 250mW.
REFER TO THE LT3845AEFE DATASHEET FOR MORE DETAILS.
2
DEMO CIRCUIT 1619A
22
HIGH VOLTAGE SYNCHRONOUS BUCK
N/A
LT3845AEFE
NC
MARTY M.
CONTROLLER WITH ADJUSTABLE OPERATING FREQUENCY
11-15-10
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
2VOUT
3VOUT
BG
VCC
BG
VOUT
TG
VIN
SW
Q3A
Si1555DL
1 6
2
C12
1uF
10V Q5
2
4
6
1
3 5
7
8
C10
1uF
10V
D5
BAV99
1
3
2
R21
C13 1uF
10V
R19 Q3B
Si1555DL
5
3 4
Q4
2
4
6
1
3 5
7
8
C11
1uF
10V
D4
BAV99
1
3
2
R18
R22
R20
L7LJCUEN2
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DEMO MANUAL DC1619A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2011
LT 0211 • 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

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