Linear Technology DC2522A User manual

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DEMO MANUAL DC2522A
Description
LT8609S
42V, 2A/3A Peak Micropower
Synchronous Step-Down Regulator
Demonstration circuit 2522A is a 42V, 2A/3A peak micro-
power synchronous step-down regulator featuring the
LT
®
8609S. The demo board is designed for 5V output
from a 5.5V to 42V input. The wide input range allows
a variety of input sources, such as automotive batter-
ies and industrial supplies. The LT8609S is a compact,
high efficiency, high speed synchronous monolithic step-
down switching regulator that consumes only 2.5μA of
quiescent current when output is regulated at 5V. Top
and bottom power switches, compensation components
and other necessary circuits are inside of the LT8609S to
minimize external components and simplify design.
The SYNC pin on the demo board is grounded by default
for low ripple Burst Mode
®
operation. Move JP1 to PULSE
SKIPPING position can change the operation mode to
pulse-skipping operation. Once JP1 is on SPREAD SPEC-
TRUM position, VCC is applied to the SYNC pin for low
EMI spread spectrum operation. To synchronous to an
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Analog Devices, Inc. All other trademarks are the property of their respective owners.
performance summary
external clock, move JP1 to SYNC and apply the external
clock to the SYNC turret. Figure 1 shows the efficiency
of the circuit.
The demo board has an EMI filter installed. The radiated
EMI performances of the board (with EMI filter) are shown
in Figures 2 and 3. The red lines in Figures 2 and 3 are
CISPR25 class 5 peak limit. To use the EMI filter, the input
should be tied to VEMI, not VIN. An inductor L2, which is
a 0Ω jumper on the board by default now, can be added
in the EMI filter to further reduce the conducted emission.
The LT8609S data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this demo manual
for DC2522A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2522A
Specifications are at TA= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Voltage Range 5.5 42 V
VOUT Output Voltage 4.8 5 5.2 V
IOUT Maximum Output Current 2 A
fSW Switching Frequency 1.85 2 2.15 MHz
EFE Efficiency at DC VIN = 12V, IOUT = 1A 93.1 %
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DEMO MANUAL DC2522A
Quick start proceDure
DC2522A is easy to set up to evaluate the performance of
the LT8609S. Refer to Figure 4 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. See Figure 5 for the proper scope
technique.
1. Set an input power supply that is capable of 42V/2A.
Then turn off the supply.
2. With power off, connect the supply to the input termi-
nals VIN and GND.
3. Turn on the power at the input.
NOTE: Make sure that the input voltage never exceeds
42V.
4. Check for the proper output voltage of 5V. Turn off the
power at the input.
5. Once the proper output voltage is established, connect
a variable load capable of sinking 2A at 5V to the output
terminals VOUT and GND. Set the current for 0A.
a. If efficiency measurements are desired, an ammeter
can be put in series with the output load in order to
measure the DC2522A’s output current.
b. A voltmeter can be placed across the output ter-
minals in order to get an accurate output voltage
measurement.
6. Turn on the power at the input.
NOTE: If there is no output, temporarily disconnect the
load to make sure that the load is not set too high.
7. Once the proper output voltage is established again,
adjust the load and/or input within the operating range
and observe the output voltage regulation, ripple volt-
age, efficiency and other desired parameters.
8. An external clock can be added to the SYNC termi-
nal when SYNC function is used (JP1 on the SYNC
position). Please ensure that the chosen RT sets the
LT8609S switching frequency to equal or below the
lowest SYNC frequency. See the data sheet section,
Synchronization.
Figure 1. Efficiency vs Load Current at 2MHz Switching Frequency
IOUT (A)
0
EFFICIENCY (%)
100
80
85
90
95
70
60
75
65
55
50 1.5
DC2522a F01
20.5 1
12V INPUT
24V INPUT
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DEMO MANUAL DC2522A
Quick start proceDure
FREQUENCY (MHz)
VERTICAL POLARIZATION
PEAK DETECTOR
AMPLITUDE (dBµV/m)
FIXED FREQUENCY
SPREAD SPECTRUM MODE
CLASS 5 PEAK LIMIT
0 300200100 700500 900
DC2522a F02
1000600400 800
–10
–5
0
5
10
15
20
25
30
35
40
45
50
Figure 2. LT8609S Demo Circuit EMI Performance in CISPR25 Radiated Emission Test, Antenna Polarization:
Vertical (VIN = 14V, VOUT = 5V, IOUT = 2A, 2MHz Switching Frequency)
FREQUENCY (MHz)
VERTICAL POLARIZATION
AVERAGE DETECTOR
FIXED FREQUENCY
SPREAD SPECTRUM MODE
CLASS 5 AVERAGE LIMIT
0 300200100 700500 900
DC2522a F03
1000600400 800
–10
–5
0
5
10
15
20
25
30
35
40
45
50
AMPLITUDE (dBµV/m)
Figure 3. LT8609S Demo Circuit EMI Performance in CISPR25 Radiated Emission Test, Antenna Polarization:
Horizontal (VIN = 14V, VOUT = 5V, IOUT = 2A, 2MHz Switching Frequency)
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DEMO MANUAL DC2522A
Quick start proceDure
Figure 4. Proper Measurement Equipment Setup
Figure 5. Measuring Output Ripple
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DEMO MANUAL DC2522A
Quick start proceDure
Figure 6. DC2522A Output Ripple (VIN = 12V, VOUT = 5V, IOUT = 2A, 2MHz Switching Frequency)
500ns/DIV DC2522a F06
VOUT
5mV/DIV
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DEMO MANUAL DC2522A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C2 CAP, X7R, 4.7µF, 50V, 10% 1206 MURATA, GRM31CR71H475KA12L
2 1 C4 CAP, X7R, 1µF, 25V, 10%, 0603 MURATA, GRM188R71E105KA12D
3 1 C5 CAP, C0G, 10pF, 25V, 5%, 0603 AVX, 06033A100JAT2A
4 1 C6 CAP, X7R, 47µF, 10V, 10%, 1210 MURATA, GRM32ER71A476KE15L
5 1 C8 CAP, X7R, 0.01µF, 16V, 10%, 0603 AVX, 0603YC103KAT2A
6 1 L1 IND, 2.2µH COILCRAFT, XFL4020-222ME
7 1 R2 RES, CHIP, 18.2k, 1/10W, 1%, 0603 VISHAY, CRCW060318K2FKEA
8 1 R3 RES, CHIP, 49.9k, 1/10W, 1%, 0603 VISHAY, CRCW060349K9FKEA
9 2 R1, R4 RES, CHIP, 1M, 1/10W, 1%, 0603 VISHAY, CRCW06031M00FKEA
10 1 R5 RES, CHIP, 182k, 1/10W, 1%, 0603 VISHAY, CRCW0603182KFKEA
11 1 U1 IC, REGULATOR, LQFN-16 LINEAR TECHNOLOGY, LT8609SEV#PBF
Additional Demo Board Circuit Components
1 1 C1 CAP, ALUM 22µF 63V SUN ELECT, 63CE22BS
2 2 C3, C10 CAP, X7R, 4.7µF, 50V, 10% 1206 MURATA, GRM31CR71H475KA12L
3 1 C9 CAP, X7R, 4.7µF, 16V, 10%, 0805 MURATA, GRM21BR71C475K73L
4 1 C11 CAP, X7R, 1µF, 50V, 10%, 0805 MURATA, GRM21BR71H105KA12L
5 1 C12 CAP, X7R, 0.1µF, 50V, 10%, 0603 MURATA, GRM188R71H104KA93D
6 1 FB1 FERRITE BEAD 0805 TDK, MPZ2012S331AT000
7 1 L2 RES, CHIP, 0Ω, 3/4W, 2010 VISHAY, CRCW20100000Z0EF
8 0 R6 (OPT) RES, 0603
Hardware: For Demo Board Only
1 9 E1 TO E9 TESTPOINT, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0
2 1 E10 (OPT) TESTPOINT, TURRET, 0.094"
3 1 JP1 DOUBLE ROW HEADER 2 × 4 0.079" SULLINS, NRPN042PAEN-RC
4 1 XJP1 SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G
5 4 MH1 TO MH4 STAND-OFF, NYLON 0.50" TALL KEYSTONE, 8833(SNAP ON)
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DEMO MANUAL DC2522A
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
5
5
4
4
3
3
2
2
1
1
DD C C
B B
A A
ALL CAPACITORS ARE 0603.
NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS ARE 0603.
SUNCON 63CE22BS
(2MHz)
SYNC SPREAD SPECTRUM PULSE SKIPPING BURST
VCC
VCC
E6
EN/UV
R2
18.2k
E5
SYNC
R4
1.00M
+
C1 22µF 63V
L1
2.2µH
XFL4020-222MEC
E9
GND
E7
TR/SS
C6
47µF 10V 1210
C11 1µF
50V
0805
C8
0.01µF
C10 4.7µF 50V 1206
R6 (Opt)
E8 PG
R3 49.9k
JP1
1 2
3 5
7
4 6
8
E3
VOUT
5V / 2A
E4
GND
C5
10pF
R5 182k
R1 1.00M
L2
0 2010
C3 4.7µF 50V 1206
E1
VEMI
5.5V - 42V
FB1
C2 4.7µF 50V 1206
C12 0.1µF 50V
U1 LT8609S
VIN
9
EN
11
SYNC
16
VCC
2
TR/SS
15
RT
1
FB 13
PG 12
SW 5
GND
17
GND
3GND
4
SW 6
NC
7
GND
8
VIN
10
GND
14
GND
18
GND
19
GND
20
GND
21
C4 1uF
E10
VIN
5.5V - 42V
E2
GND
C9 4.7µF 16V 0805
VOUT
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DEMO MANUAL DC2522A
 LINEAR TECHNOLOGY CORPORATION 2017
LT 0517 • 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 application
engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
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