DC1891A - Demo Manual

DEMO MANUAL DC1891A
LTC3862-2
Low Noise PolyPhase® SEPIC
DC/DC Converter
DESCRIPTION
Demonstration circuit 1891A is a 2-phase high efficiency
nonisolated SEPIC (single ended primary inductor converter) converter featuring the LTC®3862-2 switching
controller. The DC1891A converts a 6V to 60V input to
a 12V output and provides 6A of output current. The
converter operates at 300kHz (600kHz output ripple) with
efficiency around 90%. With a proper amount of airflow,
the DC1891A converter can generate over 6A of output
current. The DC1891A can be easily modified to generate
output voltages in the range from 0.8V to 48V.
Also, the DC1891A can be optimized for specific input voltages. The narrowing of input voltage range can increase
the converter’s efficiency. Therefore, a narrow input voltage
range is more desirable.
The LTC3862-2 can be synchronized to an external clock
of up to 400kHz. Please refer to LTC3862-2 data sheet for
design details and applications information.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology, PolyPhase and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
PERFORMANCE SUMMARY
Specifications are at TA = 25°C
PARAMETER
CONDITIONS
VALUE
Minimum Input Voltage
IOUT = 0A to 6A
6V
Maximum Input Voltage
IOUT = 0A to 6A
60V
VOUT
VIN = 6V to 60V, IOUT = 0A to 6A
12V ±3%
Typical Output Ripple VOUT
VIN = 6V to 60V, IOUT = 0A to 6A
100mVP-P
Nominal Switching Frequency
300kHz
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DEMO MANUAL DC1891A
QUICK START PROCEDURE
Demonstration circuit 1891A is easy to set up to evaluate
the performance of the LTC3862-2 circuit. Refer to Figure 1
for proper measurement equipment setup and follow the
procedure below:
4.Once the proper output voltage is established, adjust the
load within the operating range and observe the output
voltage regulation, ripple voltage, efficiency and other
parameters.
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
voltage ripple by touching the probe tip directly across
the VIN or VOUT and GND terminals. See Figure 2 for
the proper scope probe technique.
5.The DC1891A is equipped with an input capacitor CIN4
that is optional and is used to help with filtering when
the board is connected to the lab supply with long leads.
The capacitor CIN4 can be removed if the input power
source is close and has low source impedance.
1.With power off, connect the input power supply to VIN
and GND. Make sure that the input power supply has
sufficient current rating at minimum input voltage for
the required output load.
2.Turn on the power at the input.
NOTE: Make sure that the input voltage does not exceed
60V.
3.Check for the proper output voltage.
VOUT = 12V, ±3%.
If there is no output, temporarily disconnect the load
to make sure that the load is not set too high.
CHANGING THE OUTPUT VOLTAGE
To set the output voltage lower or higher than 12V, change
the bottom voltage divider resistor connected to the FB
pin of U1 (see the Schematic Diagram). Also, check the
MOSFET, output diode and capacitor voltage ratings if the
output voltage is set higher than 12V.
The optional Q5 circuit is used to get the circuit running.
Once the circuit is running, the 12V output is used to
bias U1 via D2. The start-up circuit Q5 is turned off by Q6
when VOUT gets to the level set by D3, R14 and R16 that
activates Q6. Please contact the LTC factory for details.
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DEMO MANUAL DC1891A
QUICK START PROCEDURE
DC1891a F01
Figure 1. Proper Measurement Equipment Setup
GND
VIN
DC1891a F02
Figure 2. Measuring Input or Output Ripple
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DEMO MANUAL DC1891A
QUICK START PROCEDURE
92
VIN = 12V, VOUT = 12V
IOUT = 1A
3A LOAD STEP
90
88
EFFICIENCY (%)
86
84
VOUT 200mV/DIV
82
80
78
76
6V INPUT
12V INPUT
24V INPUT
48V INPUT
74
72
70
0
1
2
3
4
IOUT (A)
5
6
7
IOUT 2A/DIV
500µs/DIV
8
DC1891a F03
Figure 3. Reducing the Input Voltage Range and Selecting
More Optimal MOSFET, Diode and Inductor Can Optimize the
Efficiency of DC1891A
OUTPUT LOAD STEP RESPONSE
The load step response of DC1891A is very fast even
though a relatively small amount of output capacitance
is present (188µF ceramic and 440µF electrolytic). The
load step transients are shown in Figure 4. To improve
load step response further or to reduce the output ripple,
more output capacitance can be added. Low ESR output
capacitors will have the greatest effect on reducing the
ripple and load step transients.
DC1891a F04
Figure 4. Fast Transient Response of DC1891A is Achieved with a
Small Amount of Output Capacitance
SOFT-START FUNCTION
The DC1891A features a soft-start circuit that controls the
inrush current and output voltage ramp at start-up. The
capacitor CSS controls the start-up period. The start-up
waveforms are shown in Figure 5.
VIN = 12V, VOUT = 12V
IOUT = 5A
START-UP
IIN 2A/DIV
VOUT 2V/DIV
50ms/DIV
DC1891a F05
Figure 5. The DC1891A Ramps the Output Slowly at Start-Up
without Generating an Input Current Surge
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DEMO MANUAL DC1891A
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
CC2
CAP, NPO 100pF, 25V, 5%, 0603
AVX 06033A101JAT2A
2
4
C3, C4, CSS, C5
CAP, X7R 0.01µF 25V 10% 0603
AVX 06033C103KAT2A
3
1
CC1
CAP, X5R 0.015µF 25V 10% 0603
AVX 06033D153KAT2A
4
1
C1
CAP, NPO 1000pF 25V 10% 0603
AVX 06033A102JAT2A
5
1
C2
CAP, X5R, 2.2µF, 25V, 10%, 0805
AVX 08053D225KAT2A
6
1
CIN4
CAP, 33µF, 63V
SUN ELECT, 63HVH33MS
7
1
CU1
CAP, X7R 4.7µF 50V 10% 1206
MURATA GRM31CR71H475KA12L
8
7
CS1 TO CS4, CIN1 TO CIN3
CAP, X7S 4.7µF 100V 20% 1812
TDK C4532X7S2A475M
9
4
COUT1 TO COUT4
CAP, X7S 47µF 16V 20% 1812
TDK CKG45NX7S1C476M
10
2
COUT5, COUT6
CAP, 220µF 16V APXE
UNITED CHEMI-CON APX160ARA221MHA0G
11
1
CF
CAP, X7R 0.01µF 16V 10% 0603
AVX 0603YC103KAT2A
12
2
D3, D5
ZENER DIODE, SOD-323
NXP SEMI PDZ6.8B
13
1
D4
DIODE, SOD-523
NXP SEMI BAS516
14
2
D1, D2
SCHOTTKY RECTIFIER, TO-277A
VISHAY V8P10-M3/86A
15
2
Q2, Q4
POWER MOSFET, PG-TDSON-8
INFINEON BSC060N10NS3G
16
1
Q5
PNP TRANSISTOR, SOT-23
NXP SEMI PBSS9110T
17
2
Q6, Q8
NPN TRANSISTOR, SOT-323
NXP SEMI PMST5550
18
1
Q7
NPN TRANSISTOR, SC-75
NXP SEMI BC847T
19
1
RC1
RES, CHIP 13.7k, 1% 0603
VISHAY CRCW060313K7FKEA
20
1
ROSC
RES, CHIP 43.2k, 1% 0603
VISHAY CRCW060343K2FKED
21
2
R4, R10
RES, CHIP 10Ω 5% 0603
VISHAY CRCW060310R0JNEA
22
2
RF, R17
RES, CHIP 0Ω, Jumper 0603
VISHAY CRCW06030000Z0EA
23
1
R9
RES, CHIP 110k, 1% 0805
VISHAY CRCW0805110KFKEA
24
1
R1
RES, CHIP 12.4k, 1% 0603
VISHAY CRCW060312K4FKEA
25
1
R3
RES, CHIP 845k, 1% 0603
VISHAY CRCW0603845KFKEA
26
1
R11
RES, CHIP 249k, 1% 0603
VISHAY CRCW0603249KFKEA
27
2
R6, R8
RES, 0.005Ω, 1/2W, 1%, 2010
VISHAY WSL20105L000FEA
28
1
R12
RES, CHIP 33k, 1% 0603
VISHAY CRCW060333K0FKEA
29
1
R13
RES, CHIP 220k, 1% 0603
VISHAY CRCW0603220KFKEA
30
1
R14
RES, CHIP 56k, 1% 0603
VISHAY CRCW060356K0FKEA
31
2
R15, R16
RES, CHIP 10k, 1% 0603
VISHAY CRCW060310K0FKEA
32
1
R19
RES, CHIP 100k, 1% 0603
NIC NRC06F1003TRF
33
1
R20
RES, CHIP 180k, 1% 0603
VISHAY CRCW0603180KFKEA
34
2
T1,T2
COUPLED INDUCTOR, 6.8µH
WÜRTH 7448709068
35
1
U1
PWM CONTROLLER LTC3862EFE-2
LINEAR TECHNOLOGY LTC3862EFE-2
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DEMO MANUAL DC1891A
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Additional Demo Board Circuit Components
1
0
Q1, Q3 (OPT)
MOSFET, PG-TDSON-8
2
0
R18 (OPT)
RES, CHIP 0603
3
0
R7, R5 (OPT)
RES, CHIP 2010
Hardware: For Demo Board Only
1
6
E3 TO E8
TESTPOINT, TURRET, 0.094"
MILL-MAX 2501-2-00-80-00-00-07-0
2
2
E1, E2
STUD, TEST PIN
PEM KFH-032-10ET
3
4
E1, E2 (2 each)
NUT BRASS, # 10-32 M/S BR PL
ANY 10-32
4
2
E1, E2
RING, LUG # 10
KEYSTONE, 8205
5
2
E1, E2
WASHER #10, TIN PLATED BRASS
ANY #10EXT BZ TN
6
4
JP1 TO JP4
HEARDER, 3PIN 1 ROW 0.079CC
SULLINS NRPN031PAEN-RC
7
4
JP1 TO JP4
SHUNT, 0.079" CENTER
SAMTEC 2SN-BK-G
8
1
SW1
SWITCHE, SEALED TOGGLE
C&K GT11MCBE (THRU-HOLE)
9
4
STAND-OFF
STAND-OFF, NYLON 0.50" TALL
KEYSTONE 8833(SNAP ON)
10
1
FAB, PRINTED CIRCUIT BOARD
DEMO CIRCUIT 1891A
dc1891af
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.
1
2
3
Q7
A
BC847T
3
2
180°
120°
3
2
1
1
RC1
13.7k
R19
100k
C5
10nF
10nF
R13
220k
+VIN
R16
10k
1
2
Q8
PMST5550
R12
33k
R15
10k
PBSS9110T
Q5
PLLFLTR
SYNC
CLKOUT
SGND
FB
ITH
SS
FREQ
3
SENSE2+
SENSE2-
B
NC
G2
PGND
G1
INTVCC
VIN
RUN
SENSE1-
SENSE1+
3V8
JP4
DMAX
U1
LTC3862EFE-2
PHASEMODE
BLANK
SLOPE
DMAX
JP3
SLOPE
B
Optional Bias Circuit
PMST5550
1
Q6
R14
56k
12
11
VOUT
P11
P10
9
8
7
6
5
4
3
2
1
10
1.66
1.0**
0.625
3
2
1
D3
PBZ6.8B
Vu1
RF 0
R9
110k
R1 12.4k
CSS
43.2k
JP2
BLANK
ROSC
3
2
1
R20 180k
CF
0.01uF
CC2
100pF
CC1
15nF
JP1
PHASE
325ns
250ns**
175ns
1
2
4
3
2
3
75%
84%**
96%
3
2
1
GND
25
1
24
0
1
1nF
Vu1
4.7uF
845k
R4 10
CU1
R3
R11 249k
C1
OFF
ON
CIN1
CIN2
CIN3
+VIN
+
C
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
D
2
CS1
47uF
16V
3
1
SCALE = NONE
GORAN P.
HZ
4.7uF
100V
4.7uF
100V
D1
V8P10
1
4.7uF
100V
E8
E7
E6
E5
E4
E3
E2
E1
+VIN
5-23-12
DATE
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900 www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
GND
GND
GND
GND
12V / 6A
Goran P.
APPROVED
E
* See Demo Manual
*
*
+VOUT
GND
6V-60V
TECHNOLOGY
VOUT
+VIN
PRODUCTION
DESCRIPTION
REVISION HISTORY
D
DATE:
N/A
SIZE
LTC3862EFE-2
DEMO CIRCUIT 1891A
Wednesday, August 01, 2012
IC NO.
E
SHEET 1
OF 1
2
REV.
LOW NOISE POLYPHASE SEPIC POWER CONVERTER
TITLE: SCHEMATIC
2
REV
4.7uF
100V
T1 7448709060
6.8uH
4
2
CS3
CS4
D2
V8P10
COUT1
COUT2
COUT3
COUT4
220uF
16V
APXE
Q3 OPT
Q4
BSC060N10NS3G
R7
OPT
R8
.005
1W
R6
.005
1W
COUT5
COUT6
Q1 OPT
CS2
Q2
BSC060N10NS3G
R5
OPT
__
ECO
T2 7448709060
6.8uH
4
3
APPROVALS
4.7uF
100V
R10 10
CIN4
33uF
63V
HVH
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APP ENG.
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
CUSTOMER NOTICE
OPT
R17
1
R18
2
C4
10nF
C2
2.2uF
3
1
C3
10nF
PDZ6.8B
D4
BAS516
13
14
15
16
17
18
19
20
21
22
23
2
D5
2
RUN
SW1
C
+
2
A
1
2
3
4
DEMO MANUAL DC1891A
SCHEMATIC DIAGRAM
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7
DEMO MANUAL DC1891A
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
dc1891af
8
Linear Technology Corporation
LT 0812 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2012
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