DC1897B - Demo Manual

DEMO MANUAL DC1897B
LTC3605A
20V, 5A Monolithic
Synchronous Step-Down
Regulator
DESCRIPTION
Demonstration circuit 1897 is a step-down converter, using
the LTC®3605A monolithic synchronous buck regulator.
The DC1897B has a maximum input voltage of 20V, and
is capable of delivering up to 5A of output current at a
minimum input voltage of 4V. The output voltage of the
DC1897B can be set as low as 0.6V, the reference voltage of the LTC3605A. At low load currents, the DC1897B
operates in discontinuous mode, and during shutdown,
it consumes 11µA of quiescent current typically. The
DC1897B can achieve efficiency over 90%. The LTC3605A
has phase-lock-loop circuits, allowing high current multiphase operation of several DC1897Bs in parallel. The
DC1897B can also track another voltage with the LTC3605A
track function. Because of the high switching frequency of
the LTC3605A, which is programmable up to 4MHz, the
DC1897B uses low profile surface mount components. All
these features make the DC1897B an ideal circuit for use
in industrial applications and distributed power systems
Design files for this circuit board are available at
http://www.linear.com/demo
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.
PERFORMANCE SUMMARY
Table 1. Performance Summary
PARAMETER
CONDITIONS
VALUE
Input Voltage Range
4V to 20V
Output Voltage Range
0.6V to 5V
Run/Shutdown
GND = Shutdown
VIN = Run
Output Voltage Regulation
VIN = 4V to 20V, IOUT = 0A to 5A
VIN = 4.7V to 20V, IOUT = 0A to 5A
VIN = 6.4V to 20V, IOUT = 0A to 5A
2.5V ±2% Typical (2.45V to 2.55V)
3.3V ±2% Typical (3.234V to 3.366V)
5V ±2% Typical (4.9V to 5.1V)
Typical Output Ripple Voltage
VIN = 12V, VOUT = 2.5V
IOUT = 5A (20MHz BW)
<20mVP-P
Discontinuous Mode
VIN = 12V, VOUT = 2.5V
VIN = 12V, VOUT = 3.3V
VIN = 12V, VOUT = 5V
IOUT < 1.25A
IOUT < 1.45A
IOUT < 1.65A
Phase
Phase = INTVCC
Phase = GND
Phase = Floating
180° Out-of-Phase: 2 Phase
120° Out-of-Phase: 3 Phase
90° Out-of-Phase: 4 Phase
Nominal Switching Frequency
RT = 162k
1MHz ±20%
Table 2. Jumper Description
JUMPER
FUNCTION
RANGE/SETTING (DEFAULT)
JP1
Output Voltage Setting
2.5V
JP5
Phase Mode (PHMODE): 180 Degrees Out-of-Phase (DOP) – 2 Phase, 120 DOP – 3 Phase,
or 90 DOP – 4 Phase
(2 PHASE) – 3 PHASE – 4 PHASE
JP6
Mode: Forced Continuous Mode (FCM) or Discontinuous Mode (DCM)
(FCM) – DCM
JP7
Run
(ON) – OFF
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1
DEMO MANUAL DC1897B
QUICK START PROCEDURE
Demonstration Circuit 1897 is easy to set up to evaluate the
performance of the LTC3605A. 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 these positions: the
2.5V output voltage header JP1, the 180° out-of-phase
(2-PHASE) position of the phase mode (PHMODE) header
JP5, the forced continuous mode (FCM) position of mode
header JP6, and the on position of run header JP7.
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 proper scope probe
measurement technique.
With the DC1897B set up according to the proper measurement configuration and equipment in Figure 1, apply 6.3V
at VIN (do not increase VIN over the rated maximum supply
voltage of 20V, or the part may be damaged). Measure
VOUT; it should read 2.5V (If desired, the quiescent current
of the circuit can be monitored now by swapping the shunt
in header JP7 into the OFF position). The output voltage
should be regulating. Measure VOUT—it should measure
2.5V ±2% (2.45V to 2.55V).
Vary the input voltage from 4V to 20V and adjust the load
current from 0 to 5A. VOUT should regulate around 2.5V
±3% (2.425V to 2.575V). Measure the output ripple voltage—it should measure less than 30mV AC.
Observe the voltage waveform at the switch pins (the
other side of the inductor from the output). Verify the
switching frequency is between 800kHz and 1.2MHz
(t = 1.25ns and 833ns), and that the switch node waveform
is rectangular in shape.
Change the shunt position on the MODE header from FCM
to DCM (discontinuous mode). Set the input voltage to
12V and the output current to any current less than 1A.
Observe the discontinuous mode of operation at the switch
node, and measure the output ripple voltage. It should
measure less than 100mV AC.
Insert the JP7 shunt into the OFF position and move the
shunt in the 2.5V output JP1 header into any of the two
remaining output voltage option headers: 3.3V (JP2) or
5V (JP3). Just as in the 2.5V VOUT test, the output voltage
should read VOUT ±1% tolerance under static line and
load conditions and ±1% tolerance under dynamic line
and load conditions (±2% total). Also, the circuit operation
in discontinuous mode will be the same. When finished,
turn off the circuit by inserting the shunt in header JP7
into the OFF position.
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DEMO MANUAL DC1897B
QUICK START PROCEDURE
Figure 1. Proper Equipment Measurement Setup
Figure 2. Measuring Input or Output Ripple
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3
DEMO MANUAL DC1897B
QUICK START PROCEDURE
Normal Switching Frequency and Output Ripple Voltage
Waveforms
VIN = 12V, VOUT = 5V, IOUT = 5A, fSW = 1MHz
Trace 1: Switch Voltage (5V/Div)
Trace 2: Output Ripple Voltage (20mV/Div AC)
Figure 3. Switch Node and Output Ripple Voltage Waveforms
Load Step Response Waveforms
VIN = 12V, VOUT = 5V, 5A Load Step (0A to 5A)
Forced Continuous Mode, fSW = 1MHz
Trace 2: Output Voltage (200mV/Div AC)
Trace 4: Output Current (2A/Div)
Figure 4. Load Step Response
Load Step Response Waveforms
Load Step Response Waveforms
VIN = 12V, VOUT = 2.5V, 5A Load Step (0A to 5A)
Forced Continuous Mode, fSW = 1MHz
Trace 2: Output Voltage (100mV/Div AC)
Trace 4: Output Current (2A/Div)
VIN = 12V, VOUT = 3.3V, 5A Load Step (0A to 5A)
Forced Continuous Mode, fSW = 1MHz
Trace 2: Output Voltage (100mV/Div AC)
Trace 4: Output Current (2A/Div)
Figure 5. Load Step Response
Figure 6. Load Step Response
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DEMO MANUAL DC1897B
QUICK START PROCEDURE
2-Phase Dual Output Waveforms
VIN = 12V, VOUT1 = 2.5V, IOUT1 = 5A, VOUT2 = 3.3V, IOUT2 = 5A,
fSW = 1MHz
Trace 1: VOUT1 Switch Voltage (10V/Div)
Trace 4: L1 Ripple Current (5A/Div)
Trace 3: VOUT2 Switch Voltage (10V/Div)
Trace 2: L2 Ripple Current (5A/Div)
Figure 7. Switch Node Voltage and Inductor Ripple Current
Waveforms of Two Circuits Operating 180° Out-of-Phase
Circuit Efficiency
VIN = 12V
Discontinuous Mode, fSW = 1MHz
Figure 8. Efficiency Graph
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DEMO MANUAL DC1897B
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
C1
CAP, 0805 2.2µF 20% 10V X5R
AVX 0805ZD225MAT2A
2
2
C2, C3
CAP, 1210 22µF 20% 25V X7R
MURATA GRM32ER61E226ME15L
3
1
C4
CAP, 0603 0.1µF 20% 25V X7R
AVX 06033C104MAT2A
4
2
C5, C12
CAP, 1206 47µF 20% 10V X5R
TAIYO YUDEN LMK316BJ476ML-T
5
1
C6
CAP, 0402 220pF 20% 50V C0G
AVX 04025A221MAT2A
6
1
C7
CAP, 0402 10pF 20% 50V C0G
AVX 04025A100MAT2A
7
1
C8
CAP, 0402 100pF 20% 50V C0G
AVX 04025A101MAT2A
8
1
D1
DIODE, CMDSH-3, SOD-323
CENTRAL SEMI. CMDSH-3TR
9
1
L1
IND 1.0µH
VISHAY IHLP2525CZER1R0M01
10
1
R1
RES, 0402 162k 1% 1/16W
VISHAY, CRCW0402162KFKED
11
1
R2
RES, 0402 10k 1% 1/16W
VISHAY CRCW040210K0FKED
12
1
R3
RES, 0402 14k 1% 1/16W
VISHAY CRCW040214K0FKED
13
1
R4
RES, 0402 3.16k 1% 1/16W
VISHAY CRCW04023K16FKED
14
1
R13
RES, 0402 0Ω JUMPER
VISHAY CRCW04020000Z0ED
15
1
U1
IC, QFN24
LINEAR TECHNOLOGY, LTC3605AEUF
Additional Demo Board Circuit Components
1
2
C9, C15
CAP, 0603 0.1µF 20% 25V X7R
AVX 06033C104MAT2A
2
1
C10
CAP, 7343 22µF 20% 35V TANT
AVX TPSY226M035R
3
0
C11
CAP, 1206 OPTION
OPTION
4
0
C13, C14
CAP, 1812 22µF 20% 25V X7R OPTION
TDK C4532X7R1E226M OPTION
5
1
R5
RES, 0402 2.21k 1% 1/16W
VISHAY CRCW04022K21FKED
6
1
R6
RES, 0402 1.37k 1% 1/16W
VISHAY CRCW04021K37FKED
7
0
R7, R12
RES, 0402 OPTION
OPTION
8
4
R8, R10, R14, R15
RES, 0402 100k 5% 1/16W
VISHAY CRCW0402100KJNED
9
1
R9
RES, 0402 150k 5% 1/16W
VISHAY CRCW0402150KJNED
11
1
R11
RES, 0402 10Ω 5% 1/16W
VISHAY CRCW040210R0JNED
Hardware—For Demo Board Only
1
9
E1-E9
TURRET
MIIL-MAX 2501-2-00-80-00-00-07-0
2
4
JP1, JP2, JP3, JP4
HEADER, SINGLE ROW, 2-PIN, 2mm
SULLINS, NRPN021PAEN-RC
3
1
JP5
HEADER, 3-PIN, DBL ROW 2mm
SULLINS, NRPN03PAEN-RC
4
1
JP6
HEADER, 2mm DBL ROW (2X2) 4-PIN
SULLINS, NRPN022PAEN-RC
5
1
JP7
HEADER, 2mm, 3-PIN
SULLINS, NRPN031PAEN-RC
6
4
JP1, JP5-JP7
SHUNT, 2mm
SAMTEC 2SN-BK-G
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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.
[1]
NOTES:
GND
PGOOD
JP7
3
2
1
4 PHASE
E8
R10
100K
TRACK
C9
0.1uF
25V
C6
220pF
14K
R3
DCM (DISCONTINUOUS MODE)
R9
150K
VIN
2 PHASE
3 PHASE
R8
100K
C7
10pF
C10 IS AN OPTIONAL CAPACITOR. IT IS INSERTED
ON THE DC1897A TO DAMPEN THE (POSSIBLE)
RINGING VOLTAGE DUE TO THE LONG INPUT LEADS.
ON A NORMAL, TYPICAL PCB, WITH SHORT TRACES,
THE CAPACITOR IS NOT NEEDED.
E6
E5
OFF
ON
RUN
4
3
6
5
JP5
4
3
PHMODE
1
2
E3
E1
FCM (FORCED CONTINUOUS MODE)
R15
100K
JP6
2
1
MODE
100K
R14
CLKIN
CLKOUT
R1
162K
6
5
4
3
2
1
C1
2.2uF
10V
ITH
TRACK
FB
MODE
PHMODE
RT
U1
LTC3605AEUF
INTVCC
24
CLKIN
RUN
7
23
CLKOUT
PGOOD
8
22
9
SW
SW
SW
SW
PVIN
PVIN
D1
CMDSH-3
SGND
21
INTVCC
0
R13
L1
1uH
C2
22uF
25V

 
 

C4
0.1uF
25V



13
14
15
16
17
18
C15
0.1uF
25V
R11 10








10
VOUT
19
PGND
20
BOOST
SW
11
SVIN
SW
12
R12
OPT
PGND
25
C8
100pF
C3
22uF
25V
1
REV
5V
JP3
R6
1.37K
C12
47uF
6.3V
1206
TECHNOLOGY
GND
OPT.
JP4
R7
OPT.
E9
C11
47uF
6.3V
OPT
GND
E7
VOUT
2.5V / 3.3V / [email protected]
E4
E2 4V to 20V
VIN

 1
LTC3605AEUF
DEMO CIRCUIT 1897B
11/07/13 10:52:40

N/A
TOM G.
APPROVED
 1
1



 


Vout SELECT
3.3V
JP2
R5
2.21K
C5
47uF
6.3V
1206
C14 + C10 [1]
22uF
22uF
25V
35V
OPT
VIN
DATE
11/01/13
5A MONOLITHIC SYNCHRONOUS
BUCK REGULATOR


REVISION HISTORY
PRODUCTION
DESCRIPTION
2.5V
JP1
R4
3.16K
R2
10.0K
C13
22uF
25V
OPT
 
ECO
DEMO MANUAL DC1897B
SCHEMATIC DIAGRAM
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7
DEMO MANUAL DC1897B
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
dc1897bf
8
Linear Technology Corporation
LT 1213 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2013
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