DC1864A - Demo Board Manual

DEMO MANUAL DC1864A
LTC3621-2
17V, 1A Monolithic Synchronous
Step-Down Regulator
DESCRIPTION
Demonstration circuit 1864A is a step-down converter,
capable of delivering up to 1A of output current from a
minimum input voltage of 2.7V. The DC1864A uses the
power-saving LTC®3621-2 2.25MHz monolithic synchronous buck regulator that comes in a tiny 2mm × 3mm
6-lead DFN package. The LTC3621-2 IC quiescent currents
can be as low as 3.5µA in normal operation, and less
than 0.1µA in shutdown. The output voltage range of the
DC1864A is from as low as 0.6V, the reference voltage of
the LTC3621‑2, to as high as the maximum input voltage,
17V. The DC1864A can operate in three distinct operating
PERFORMANCE SUMMARY
PARAMETER
Input Voltage Range
Output Voltage Range
Run/Shutdown
modes: Burst Mode® for highest efficiency at low output
currents, forced continuous mode for lowest output ripple
voltage, and pulse-skipping mode for the best compromise
operation between the two other modes, by setting the
MODE pin to INTVCC (3.6V), INTVCC/2, or ground respectively. All these features make the DC1864A an ideal
circuit for use in any high efficient, low power application.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Specifications are at TA = 25°C
CONDITIONS
Output Voltage Regulation
Typical Output Ripple Voltage
Nominal Switching Frequency
Operation Modes
Burst Mode-to-CCM Operation
INTVCC
RUN Pin = GND
RUN Pin = VIN
VIN = 2.7V to 17V, IOUT = 0A to 1A
VIN = 2.7V to 17V, IOUT = 0A to 1A
VIN = 2.7V to 17V, IOUT = 0A to 1A
VIN = 3.5V to 17V, IOUT = 0A to 1A
VIN = 5.2V to 17V, IOUT = 0A to 1A
VIN = 12V, VOUT = 5V, IOUT = 1A (20MHz BW)
MODE Pin = INTVCC
MODE Pin = GND
MODE Pin = INTVCC/2
VIN = 12V, VOUT = 1.2V
VALUE
2.7V to 17V
0.6V to VIN
Shutdown
Operating
1.2V ±3% Typ. (1.164V to 1.236V)
1.8V ±3% Typ. (1.746V to 1.854V)
2.5V ±3% Typ. (2.425V to 2.575V)
3.3V ±3% Typ. (3.201V to 3.399V)
5V ±3% Typ. (4.85V to 5.15V)
< 20mVP-P
2.25MHz ±8%
Burst Mode Operation
Pulse-Skipping
Forced Continuous
IOUT < 500mA
3.6V ±8.33% (3.3V to 3.9V)
Table 1. Jumper Description
JUMPER
FUNCTION/RANGE
SETTING
JP1
Run: ON – OFF.
ON
JP2
Mode: Burst Mode Operation (BM) or Pulse-Skipping Mode (PS)
BM
JP3
Output Voltage Setting.
1.2V
dc1864af
1
DEMO MANUAL DC1864A
QUICK START PROCEDURE
Demonstration circuit 1864 is easy to set up to evaluate the
performance of the LTC3621-2. 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 the correct locations:
1.2V position of the output voltage header JP3, into the
BM (Burst Mode operation) position of MODE header JP2,
and into the ON position of RUN header JP1.
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 DC1864 set up according to the proper measurement configuration and equipment in Figure 1, apply 5V at
VIN (Do not hot-plug VIN or increase VIN over the rated
maximum supply voltage of 17V, or the part may be damaged.). Measure VOUT; it should read 1.2V. (If desired, the
quiescent current of the circuit can be monitored now by
swapping the shunt in header JP1 into the OFF position.)
The output voltage should be regulating. Draw 500mA out
of the output and measure VOUT — it should measure 1.2V
±2% (1.176V to 1.224V). Verify the switching frequency
is between 1.8MHz and 2.6MHz (t = 55ns and 38ns), and
that the switch node waveform is rectangular in shape.
Set the input voltage to 12V and the output current to than
100mA. Observe the Burst Mode operation at the switch
node (the pad of the inductor opposite from the output),
and measure the output ripple voltage. It should measure
less than 100mV. Change the shunt position on the MODE
header from BM to PS (pulse-skipping mode) and observe
the voltage waveform at the switch pins. To achieve forced
continuous operation, insert two 100k resistors at the
pads for R1 and R2. These resistors develop a voltage of
INTVCC/2 at the MODE pin, which is the voltage setting
for forced continuous operation.
Insert the JP1 shunt into the OFF position and move the
shunt in the 1.2V output JP3 header into any of the remaining output voltage option headers: 1.8V (JP4), 2.5V
(JP5), 3.3V (JP6) or 5V (JP7). Just as in the 1.2V VOUT
test, the output voltage should read VOUT ±2% tolerance
under static line and load conditions and ±1% tolerance
under dynamic line and load conditions (±3% total). Also,
the circuit switch operation in Burst or pulse-skipping
mode operation will remain the same. There is an extra
output voltage header, JP8, to allow the user to easily set
the output to their desired value
When finished, turn off the circuit by inserting the shunt
in header JP1 into the OFF position.
Vary the input voltage from 2.7V to 17V and the load current from 0 to 1A. VOUT should regulate around 1.2V ±3%
(1.164V to 1.236V). Measure the output ripple voltage; it
should measure less than 20mV AC.
dc1864af
2
DEMO MANUAL DC1864A
QUICK START PROCEDURE
Figure 1. Proper Equipment Measurement Setup
Figure 2. Measuring Input or Output Ripple
dc1864af
3
DEMO MANUAL DC1864A
QUICK START PROCEDURE
OUTPUT VOLTAGE
50mV/DIV AC
OUTPUT CURRENT
500mA/DIV
VIN = 12V, VOUT = 1.2V
500mA LOAD STEP (500mA TO 1A)
PULSE-SKIPPING MODE
fSW = 1MHz
Figure 3. Load Step Response
OUTPUT VOLTAGE
50mV/DIV AC
OUTPUT CURRENT
500mA/DIV
VIN = 12V, VOUT = 2.5V
500mA LOAD STEP (500mA TO 1A)
PULSE-SKIPPING MODE
fSW = 1MHz
Figure 4. Load Step Response
OUTPUT VOLTAGE
50mV/DIV AC
OUTPUT CURRENT
500mA/DIV
VIN = 12V, VOUT = 3.3V
500mA LOAD STEP (500mA TO 1A)
PULSE-SKIPPING MODE
fSW = 1MHz
Figure 5. Load Step Response
dc1864af
4
DEMO MANUAL DC1864A
QUICK START PROCEDURE
OUTPUT VOLTAGE
100mV/DIV AC
OUTPUT CURRENT
500mA/DIV
VIN = 12V, VOUT = 5V
500mA LOAD STEP (500mA TO 1A)
PULSE-SKIPPING MODE
fSW = 1MHz
Figure 6. Load Step Response
90
85
VIN = 12V, Burst Mode OPERATION
fSW = 2.25MHz
L = 2.2µH, Coilcraft XFL-3012
EFFICIENCY (%)
80
75
70
VO = 5V
VO = 3.3V
VO = 2.5V
VO = 1.8V
VO = 1.2V
65
60
55
0.0001
0.001
0.01
0.1
1
LOAD CURRENT (A)
Figure 7. Circuit Efficiency
dc1864af
5
DEMO MANUAL DC1864A
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
CFF
CAP., X7R, 22pF, 50V, 0402
AVX 04025A220KAT
2
1
C1
CAP., X5R, 10µF, 25V, 10%, 1206
AVX 12063D106KAT
3
2
C2, C3
CAP., X5R, 22µF, 25V, 10%, 1206
AVX 12063D226KAT
4
1
C4
CAP., X5R, 1µF, 6.3V,20%, 0402
TDK, C1005X5R0J105M
5
1
L1
IND, FIXED INDUCTOR, 2.2µH
COILCRAFT., XFL3012-222MEB
6
2
R3, RSET
RES., CHIP, 619k, 1%, 0402
VISHAY CRCW0402619KFKED
7
1
U1
LTC3621EDCB-2, 6-LEAD DFN PACKAGE
LINEAR TECH., LTC3621EDCB-2#PBF
SANYO, 20TQC8R2M
Additional Demo Board Circuit Components
1
1
C1A
CAP., X5R, 8.2µF 20V, SIZE B2, 3528-7343
2
0
R1, R2 OPT
RES., CHIP, 0402
3
1
R4
RES., CHIP, 309k, 1%, 0402
VISHAY CRCW0402309KFKED
4
1
R5
RES., CHIP, 196k, 1%, 0402
VISHAY CRCW0402196KFKED
5
1
R6
RES., CHIP, 137k, 1%, 0402
VISHAY CRCW0402137KFKED
VISHAY CRCW040284K5FKED
6
1
R7
RES., CHIP, 84.5k, 1%, 0402
7
0
R8 OPT
RES., CHIP, 0402
Hardware
1
8
E1-E8
TESTPOINT, TURRET, 0.095"
MILL-MAX, 2501-2-00-80-00-00-07-0
2
2
JP1, JP2
2MM SINGLE ROW HEADER, 3-PIN
SULLINS, NRPN031PAEN-RC
3
6
JP3-JP8
2MM SINGLE ROW HEADER, 2-PIN
SULLINS, NRPN021PAEN-RC
4
3
JP1-JP3
SHUNT,
SAMTEC, 2SN-BK-G
dc1864af
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
D
C1A
8.2uF
25V
+
BM (Burst Mode)
E7
E1
SYNC
GND
5
E5
E3
PS (Pulse-Skip)
MODE/SYNC (Forced Continuous)
INTVCC
VIN
2.7V - 17V
VIN
1
3
JP2
2
OFF
ON
R2
100k
OPT
R1
100k
OPT
C1
10uF
1
3
5
C4
1uF
4
RUN
2
JP1
4
6
5
3
2
4
1
3
L1
2.5V
JP5
R5
196k
Rset
619k




1.8V
JP4
R4
309k

1.2V
JP3
R3
619k
2.2uH



7
GND
FB
SW









MODE/SYNC
INTVCC
RUN
VIN
LTC3621EDCB-2
U1
3
5.0V
JP7
R7
84.5k



C2
22uF
TECHNOLOGY
E6
E4
C3
22uF
E2
GND
GND
1A
VOUT
2




1
 

 



 


USER SELECT
JP8
R8
OPT
CFF
22pF
VOUT
1
17V VIN SYNCHRONOUS STEP-DOWN REGULATOR
 
3.3V
JP6
R6
137k
2
A
B
C
D
DEMO MANUAL DC1864A
SCHEMATIC DIAGRAM
dc1864af
7
DEMO MANUAL DC1864A
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
dc1864af
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
Similar pages