DC1895A - Demo Manual

DEMO MANUAL DC1895A
LTC3633A
Dual Channel 3A 20V Monolithic
Synchronous Step-Down Regulator Board
Description
Demonstration circuit DC1895 is a dual output regulator
consisting of two constant-frequency step-down converters, based on the LTC3633A monolithic dual channel
synchronous buck regulator. The DC1895 has an input
voltage range of 3.6V to 20V, with each regulator capable
of delivering up to 3A of output current. The DC1895 can
operate in either Burst Mode® operation or forced continuous mode. In shutdown, the DC1895 can run off of less
than 15µA total. The DC1895 is a very efficient circuit: over
90% for either circuit. The DC1895 uses the 28-Pin QFN
LTC3633AEUFD package, which has an exposed pad on
Performance Summary
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
Run
Output Voltage VOUT1
Typical Output Ripple VOUT1
Output Regulation VOUT1
Output Voltage VOUT2
Typical Output Ripple VOUT2
Output Regulation VOUT2
Nominal Switching Frequencies
Burst Mode Operation
Phase
INTVCC
V2P5
the bottom-side of the IC for better thermal performance.
These features, plus a programmable operating frequency
range from 500kHz to 4MHz (2MHz switching frequency
with the RT pin connected to INTVCC), make the DC1895
demo board an ideal circuit for use industrial or distributed
power applications.
Design files for this circuit board are available at
http://www.linear.com/demo
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.
Specifications are at TA = 25°C
CONDITIONS
RUN Pin = GND
RUN Pin = VIN
VIN = 3.6V to 20V, IOUT1 = 0A to 3A
VIN = 12V, IOUT1 = 3A (20MHz BW)
Line
Load
VIN = 3.6V to 20V, IOUT2 = 0A to 3A
VIN = 12V, IOUT2 = 3A (20MHz BW)
Line
Load
RT Pin connected to 324k
RT Pin = INTVCC
Channel 1: VIN = 12V, VOUT1 = 1.8V, fSW = 1 MHz
Channel 2: VIN = 12V, VOUT2 = 3.3V, fSW = 1 MHz
Channel 1: VIN = 12V, VOUT1 = 1.8V, fSW = 2 MHz
Channel 2: VIN = 12V, VOUT2 = 3.3V, fSW = 2 MHz
Phase Pin = INTVCC
Phase Pin = GND
VALUE
3.6V
20V
Shutdown
Operating
1.2V ±4% (1.152V to 1.248V)
1.5V ±4% (1.44V to 1.56V)
1.8V ±4% (1.728V to 1.872V)
< 30mVP-P
±1%
±1%
2.5V ±4% (2.4V to 2.6V)
3.3V ±4% (3.168V to 3.432V)
5V ±4% (4.8V to 5.2V)
< 30mVP-P
±1%
±1%
1MHz
2MHz
IOUT1 = 1.3A
IOUT2 = 850mA
IOUT1 = 800mA
IOUT2 = 500mA
Out-of-Phase
In Phase
3.3V
2.5V
dc1895afa
1
DEMO MANUAL DC1895A
Quick Start Procedure
The DC1895 is easy to set up to evaluate the performance
of the LTC3633A. For a proper measurement equipment
configuration, set up the circuit according to the diagram
in Figure 1.
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 the proper scope probe
technique in Figure 2.
Please follow the procedure outlined below for proper
operation.
1.Connect the input power supply to the VIN and GND
terminals. Connect the loads between the VOUT and GND
terminals. Refer to Figure 1 for the proper measurement
equipment setup.
Before proceeding to operation, insert jumper shunts
XJP1 and XJP2 into the OFF positions of headers JP1
and JP2, shunt XJP11 into the ON position (180° outof-phase) of PHASE header JP11, shunts XJP3 and
XJP4 into the soft-start (ss) positions of headers JP3
and JP4, shunt XJP8 into the forced continuous mode
(FCM) position of MODE header JP8, shunt XJP14
into the 1MHz position of the frequency (FREQ) header
JP14, shunts XJP12 and XJP13 into the external (EXT)
compensation positions of headers JP12 and JP13, and
shunt XJP6 into the VOUT1 voltage options of choice of
header JP6: 1.2V, 1.5V, or 1.8V, and a shunt into the
VOUT2 voltage option of choice: 2.5V (header JP15),
3.3V (header JP5), or 5V (header JP7).
2.Apply 5.5V at VIN. Measure both VOUTs; they should
read 0V. If desired, one can measure the shutdown
supply current at this point. The supply current will be
less than 100µA in shutdown.
2
3.Turn on VOUT1 and VOUT2 by shifting shunts XJP1 and
XJP2 from the OFF positions to the ON positions. Both
output voltages should be within a tolerance of ±2%.
4.Vary the input voltage from 5.8V (the minimum VIN is
dependent on VOUT) to 20V, and the load currents from
0A to 3A. Both output voltages should be within ±4%
tolerance.
5.Set the load current of both outputs to 3A and the
input voltage to 20V, and then measure each output
ripple voltage (refer to Figure 2 for proper measurement technique); they should each measure less than
30mVAC. Also, observe the voltage waveforms at the
switch nodes (Pins 23 and 24 for reg.1 and 13 and 14
for reg.2) of each regulator. The switching frequencies
should be between 800kHz and 1.2MHz (t = 1.25µs
and 0.833µs). To realize 2MHz operation, change the
shunt position on header JP14. In all cases, both switch
node waveforms should be rectangular in shape, and
180°out-of-phase with each other. Change the shunt
position on header JP11 to set the switch waveforms in
phase with respect to each other. To operate the ckt.s in
Burst Mode Operation, change the shunt in header JP8
to the Burst Mode position. When finished, insert shunts
XJP1 and XJP2 to the OFF position(s) and disconnect
the power.
Warning: If the power for the demo board is carried in
long leads, the input voltage at the part could “ring”, which
could affect the operation of the circuit or even exceed
the maximum voltage rating of the IC. To eliminate the
ringing, a small tantalum capacitor (for instance, AVX
part number TPSY226M035R0200) is inserted on the
pads between the input power and return terminals on
the bottom of the demo board. The (greater) ESR of the
tantalum will dampen the (possible) ringing voltage due
to the use of long input leads. On a normal, typical PCB,
with short traces, this capacitor is not needed.
dc1895afa
DEMO MANUAL DC1895A
Quick Start Procedure
–
–
+ +
LOAD
–
–
+
–
+ –
+
+
VO1
VS1
–
+
+
+
–
–
+
+
–
VS2
–
+
LOAD
–
VO2
dc1895af F01
Figure 1. Proper Measurement Equipment Setup
GND
VIN
Figure 2. Measuring Input or Output Ripple
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3
DEMO MANUAL DC1895A
Quick Start Procedure
VIN = 12V, VOUT1 = 1.8V at IOUT1 = 3A, VOUT2 = 3.3V at IOUT2 = 3A
FORCED CONTINUOUS MODE fSW = 1MHz
EXTERNAL COMPENSATION: RITHX = 13k, CITHX = 220pF
TRACE 1: VOUT1 (10V/DIV)
TRACE 3: VOUT1 AC VOLTAGE (20mV/DIV AC)
TRACE 2: VOUT2 (10V/DIV)
TRACE 4: VOUT2 AC VOLTAGE (20mV/DIV AC)
Figure 3. LTC3633A Switch Operation
4
dc1895afa
DEMO MANUAL DC1895A
Quick Start Procedure
VIN = 12V, VOUT1 = 1.8V, 3A LOAD STEP (0A < to > 3A)
FORCED CONTINUOUS MODE fSW = 2MHz
EXTERNAL COMPENSATION: RITH = 13k, CITH = 220pF
TRACE 3: OUTPUT VOLTAGE (100mV/DIV AC)
TRACE 4: OUTPUT CURRENT (1A/DIV)
Figure 4. VOUT1 Load Step Response
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5
DEMO MANUAL DC1895A
Quick Start Procedure
VIN = 12V, VOUT2 = 3.3V, 3A LOAD STEP (0A < to > 3A)
FORCED CONTINUOUS MODE fSW = 2MHz
EXTERNAL COMPENSATION: RITH = 13k, CITH = 220pF
TRACE 3: OUTPUT VOLTAGE (100mV/DIV AC)
TRACE 4: OUTPUT CURRENT (1A/DIV)
Figure 5. VOUT2 Load Step Response
6
dc1895afa
DEMO MANUAL DC1895A
Quick Start Procedure
100
90
VO2 = 3.3V, fSW = 1 MHz
VO2 = 3.3V, fSW = 2 MHz
VO1 = 1.8V, fSW = 1 MHz
VO1 = 1.8V, fSW = 2 MHz
80
70
EFFICIENCY (%)
60
50
40
30
20
VIN = 12V
Burst Mode OPERATION
L1 = 1 µH
L2 = 2.2 µH
2020BZ VISHAY
10
0
1.00E-03
1.00E-02
1.00E-01
LOAD CURRENT (A)
1.00E+00
1.00E+01
dc1895af F06
Figure 6. LTC3633A DC1895 Efficiency
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7
DEMO MANUAL DC1895A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
2
C1, C2
CAP, 0603, 0.1µF, 10%, 50V, X7R
TDK C1608X7R1H104K
2
2
CFFW1, CFFW2
CAP, 0402, 10pF, 5%, 25V, NPO
AVX 04023A100JAT2A
3
4
CIN1 to CIN4
CAP, 1210, 22µF, 20%, 25V, X7R
TAIYO YUDEN TMK325B7226MM-TR
4
4
COUT1 to COUT4
CAP, 1206, 22µF, 20%, 6.3V, X5R
TAIYO YUDEN JMK316BJ226ML-T
5
1
CVCC
CAP, 0603, 1µF, 10%, 16V, X5R
AVX 0603YD105KAT2A
6
1
L1
IND, 1.0µH
VISHAY IHLP-2020BZER1R0M01
7
1
L2
IND, 2.2µH
VISHAY IHLP-2020BZER2R2M01
8
2
R3, R5
RES, 0402, 29.4kΩ, 1%, 1/16W
VISHAY CRCW040229K4FKED
9
1
R4
RES, 0402, 84.5kΩ, 1%, 1/16W
VISHAY CRCW040284K5FKED
10
1
R8
RES, 0402, 11.5kΩ, 1%, 1/16W
VISHAY CRCW040211K5FKED
11
1
U1
IC, DUAL STEP-DOWN REGULATOR
LINEAR TECH, LTC3633AEUFD
Additional Demo Board Circuit Components
1
0
CC1, CC2
CAP, 0402, 10pF, 5%, 25V, NPO OPTION
AVX 04023A100JAT2A OPTION
2
2
CIN5, CIN6
CAP, 603,2 3.3µF, 20%, 35V TANT
AVX TAJW335M035R
3
2
CITH1, CITH2
CAP, 0402, 220pF, 10%, 25V C0G
AVX 04023A221KAT2A
4
0
CLDO
CAP, 0603, 1µF, 10%, 16V, X5R OPTION
AVX 0603YD105KAT2A OPTION
5
2
COUT5, COUT6
CAP, 0805, 10µF, 20%, 6.3V, X5R
TDK C2012X5R0J106M
6
2
CTR1, CTR2
CAP, 0402, 4700pF, 10%, 50V, X7R
AVX 04025C472KAT
7
2
CVCC1, C2P5
CAP, 0603, 1µF, 10%, 16V, X5R
AVX 0603YD105KAT2A
8
2
C2P5, CVCC1
CAP, 0603, 1µF, 10%, 16V, X5R
AVX 0603YD105KAT2A
9
2
RITH1, RITH2
RES, 0402, 13kΩ, 1%, 1/16W
NIC NRC04F1302TRF
10
2
RPG1, RPG2
RES, 0402, 100kΩ, 5%, 1/16W
VISHAY CRCW0402100KJNED
11
3
R1, R2, RPHMDE
RES, 0402, 1MΩ, 5%, 1/16W
VISHAY CRCW04021M00JNED
12
1
RT
RES, 0402, 324kΩ, 1%, 1/16W
VISHAY CRCW0402324KFKED
13
2
RTR1, RTR2
RES, 0402, 0Ω, JUMPER
VISHAY CRCW04020000Z0ED
14
0
RTR3, RTR4
RES, 0402, OPTION
OPTION
15
1
R6
RES, 0402, 18.7kΩ, 1%, 1/16W
VISHAY CRCW040218K7FKED
16
1
R7
RES, 0402, 19.6kΩ, 1%, 1/16W
VISHAY CRCW040219K6FKED
17
1
R9
RES, 0402, 14.7kΩ, 1%, 1/16W
VISHAY CRCW040214K7FKED
18
1
R10
RES, 0402, 26.7kΩ, 1%, 1/16W
VISHAY CRCW040226K7FKED
19
1
R11
RES, 0402, 10kΩ, 5%, 1/16W
VISHAY CRCW040210K0JNED
TURRET
MILL-MAX 2501-2-00-80-00-00-07-0
Hardware: For Demo Board Only
1
16
E1 to E16
2
8
JP1 to JP4, JP11 toJP14
HEADER, 3Pin, 2mm
SULLINS, NRPN031PAEN-RC
3
3
JP5, JP7, JP15
HEADER, 2Pin, 2mm
SULLINS, NRPN021PAEN-RC
4
2
JP6, JP8
HEADER, 3Pin, DBL ROW 2mm
SULLINS, NRPN032PAEN-RC
5
11
JP1 to JP4, JP6 to JP8,
JP11 to JP14
SHUNT, 2mm
SAMTEC 2SN-BK-G
8
dc1895afa
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
D
E16
E2
E15
E6
E4
E1
[1]
CIN5
3.3uF
35V
6032
[1]
+ CIN6
3.3uF
35V
6032
+
3
5
4
6
CIN4
22uF
25V
1210
CIN3
22uF
25V
1210
VIN
VIN
JP6
1
2
VO1 SELECT
1.8V
1.5V
CIN2
22uF
25V
1210
R3
29.4K
1%
1M
RPHMDE
INT
EXT
3
2
1
2MHz
(INT.)
1MHz
JP12
ITH1
L1 1.0uH
3
2
1
VIN
C1
0.1uF
R1 1M
JP3
3
2
1
23
24
20
5
2. ALL RESISTOR AND CAPACITOR CASE SIZE ARE 0402.
4
11
9
12
14
13
17
18
6
JP4
SS
VIN
3
2
1
TRACK
CC2
10pF
OPT
INTVCC
220pF
CITH2
RITH2
13K
1%
C2
L2 2.2uH
0.1uF


R2 1M
3
2
1
TRACK/SS2
JP14
3










6
JP13
ITH2
5
3
1
RTR4
OPT
R8 11.5K 1%
R6 18.7K 1%
R10 26.7K 1%
COUT2
22uF
6.3V
1206
C2P5
1uF
5V
3.3V
2.5V
2


N/A

JP7
JP5
GND
GND
VOUT2
V2P5
GND
TECHNOLOGY
SYNC
APPROVED
TOM G.
1
 1
LTC3633AEUFD
DEMO CIRCUIT 1895A
10/16/12 14:29:17

 1
1



 


R11
10k
E12
DATE
08/23/12
PGOOD2
TRACK2
VO2 SELECT
E14
E7
E5
E13
E3
E8
E11
1
DUAL SYNCHRONOUS STEP-DOWN
REGULATOR
 
CLDO
1uF
OPT
COUT6
10uF
6.3V
0805
JP15
COUT4
22uF
6.3V
1206
VOUT2
0
RTR2
PROTO
1
REVISION HISTORY
DESCRIPTION
REV
FCM (FORCED CONTINUOUS MODE)
 
 
ECO
BURST MODE
SYNC
INTVCC
INT

JP8
MODE
3
2
1
2
R4
84.5K
1%
EXT
OFF
ON
CFFW2
10pF
JP2
RUN2
4

ITH2
VFB2
VON2
SW2
SW2
BOOST2
V2P5
RUN2
RPG2
100K
CTR2
4700pF
3
RT
324K
1%
220pF
CITH1
ITH1
VFB1
VON1
VIN
LTC3633AEUFD
U1
1uF
1uF
CVCC
2
INTVCC
INTVCC
RITH1
13K
1%
26
28
25
SW1
SW1
BOOST1
PHMODE
RUN1
VIN
CTR1
4700pF
3
CVCC1
INTVCC
E10
2
1
FREQ
CC1
10pF
OPT
2
3
RPG1
100K


JP1
CFFW1
10pF
OFF
ON
RUN1
TRACK
SS
TRACK/SS1
[1] CIN5 AND CIN6 ARE INSERTED ON DC1895A TO DAMPEN THE (POSSIBLE) RINGING VOLTAGE DUE
TO THE USE OF LONG INPUT LEADS. ON A NORMAL, TYPICAL PCB, WITH SHORT TRACES,
CIN5 AND CIN6 ARE NOT NEEDED.
R9 14.7K 1%
R7 19.6K 1%
R5 29.4K 1%
COUT1
22uF
6.3V
1206
INTVCC
1.2V
3
2
1
CIN1
22uF
25V
1210
COUT3
22uF
6.3V
1206
VOUT1
JP11
PHASE
OFF
ON
RTR3
OPT
COUT5
10uF
6.3V
0805
0
RTR1
NOTES: UNLESS OTHERWISE SPECIFIED,
VIN2
VIN1
GND
GND
3A
VOUT1
PGOOD1
TRACK1
E9
4
1
PGOOD1
21
22
PVIN1
PVIN1
RT
5
INTVCC
INTVcc
27
TRACK/SS1
10
TRACK/SS2
19
SGND
7
PGND
29
8
PGOOD2
15
16
PVIN2
PVIN2
MODE/SYNC
4
5
A
B
C
D
DEMO MANUAL DC1895A
Schematic Diagram
dc1895afa
9
DEMO MANUAL DC1895A
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
10 Linear Technology Corporation
dc1895afa
LT 0514 REV A • 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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