DC2458A - Demo Manual

DEMO MANUAL DC2458A
LT8608
42V, 1.5V Micropower Synchronous
Step-Down Regulator
DESCRIPTION
Demonstration circuit 2458A is a 42V, 1.5A micropower
synchronous step-down regulator featuring the LT®8608.
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 batteries and industrial supplies. The LT8608 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 LT8608 to minimize external components
and simplify design.
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 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 pulseskipping operation. Once JP1 is on SPREAD SPECTRUM
position, VCC is applied to the SYNC pin for low EMI spread
spectrum operation. To synchronous to an external clock,
Design files for this circuit board are available at
http://www.linear.com/demo/DC2458A
The LT8608 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 DC2458A.
L, LT, LTC, LTM, Linear Technology, Burst Mode 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
SYMBOL
PARAMETER
CONDITIONS
VIN
Input Voltage Range
5.5
VOUT
Output Voltage
4.8
IOUT
Maximum Output Current
1.5
fSW
Switching Frequency
1.85
EFE
Efficiency at DC
VIN = 12V, IOUT = 0.75A
MIN
TYP
MAX
UNITS
42
V
5
5.2
V
2
2.15
MHz
A
92.2
%
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1
DEMO MANUAL DC2458A
QUICK START PROCEDURE
DC2458A is easy to set up to evaluate the performance
of the LT8608. Refer to Figure 4 for proper measurement
equipment setup and follow the procedure below:
a.If efficiency measurements are desired, an ammeter can be put in series with the output load in
order to measure the DC2458A’s output current.
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.
b.A voltmeter can be placed across the output terminals in order to get an accurate output voltage
measurement.
1. Set an input power supply that is capable of 42V/1.5A.
Then turn off the supply.
2.With power off, connect the supply to the input
terminals 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 1.5A at 5V to
the output terminals VOUT and GND. Set the current
for 0A.
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
voltage, efficiency and other desired parameters.
8.An external clock can be added to the SYNC terminal when SYNC function is used (JP1 on the SYNC
position). Please ensure that the chosen RT sets the
LT8608 switching frequency to equal or below the
lowest SYNC frequency. See the data sheet section,
Synchronization.
100
95
12V INPUT
90
EFFICIENCY (%)
85
24V INPUT
80
75
70
65
60
55
50
0
0.5
1
IOUT (A)
1.5
DC2458a F01
Figure 1. Efficiency vs Load Current at 2MHz Switching Frequency
2
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DEMO MANUAL DC2458A
QUICK START PROCEDURE
Figure 2. LT8608 Demo Circuit EMI Performance in CISPR25 Radiated Emission Test,
Antenna Polarization: Vertical (VIN = 14V, VOUT = 5V, IOUT = 1.5A, 2MHz Switching Frequency)
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DEMO MANUAL DC2458A
QUICK START PROCEDURE
Figure 3. LT8608 Demo Circuit EMI Performance in CISPR25 Radiated Emission Test,
Antenna Polarization: Horizontal (VIN = 14V, VOUT = 5V, IOUT = 1.5A, 2MHz Switching Frequency)
4
dc2458af
DEMO MANUAL DC2458A
QUICK START PROCEDURE
Figure 4. Proper Measurement Equipment Setup
Figure 5. Measuring Output Ripple
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5
DEMO MANUAL DC2458A
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
C2
CAP, X7R, 4.7µF, 50V, 10% 1206
MURATA, GRM31CR71H475K
2
1
C4
CAP, X7R, 0.22µF, 16V, 10%, 0603
AVX, 0603YC224KAT2A
3
1
C5
CAP, C0G, 10pF, 25V, 5%, 0603
AVX, 06033A100JAT2A
4
1
C6
CAP, X7R, 47µF, 10V, 10%, 1210
MURATA, GRM32ER71A476KE20L
5
1
C7
CAP, X7R, 1µF, 25V, 10%, 0603
MURATA, GRM188R71E105KA12D
6
1
C8
CAP, X7R, 0.01µF, 16V, 10%, 0603
AVX, 0603YC103KAT2A
7
1
L1
IND, 2.2µH
COILCRAFT, XFL4020-222MEC
8
1
R2
RES, CHIP, 18.2k, 1/10W, 1%, 0603
VISHAY, CRCW060318K2FKEA
9
1
R3
RES, CHIP, 49.9k, 1/10W, 1%, 0603
VISHAY, CRCW060349K9FKEA
10
2
R1, R4
RES, CHIP, 1M, 1/10W, 1%, 0603
VISHAY, CRCW06031M00FKEA
11
1
R5
RES, CHIP, 187k, 1/10W, 1%, 0603
VISHAY, CRCW0603187KFKEA
12
1
U1
IC, REGULATOR, MSE10
LINEAR TECHNOLOGY, LT8608EMSE#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, GRM31CR71H475K
3
1
C9
CAP, X7R, 4.7µF, 16V, 10%, 0805
MURATA, GRM21BR71C475K73L
4
1
C11
CAP, X7R, 1µF, 50V, 10%, 0805
TDK, C2012X7R1H105K
5
2
C12, C13
CAP, X7R, 0.1µF, 50V, 10%, 0603
MURATA, GRM188R71H104KA93D
6
1
FB1
FERRITE BEAD 0805
TDK, MPZ2012S221AT000
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"
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)
6
MILL-MAX, 2501-2-00-80-00-00-07-0
dc2458af
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
GND
VEMI
5.5V - 42V
VIN
5.5V - 42V
E2
E1
E10
5
E9
E7
VCC
E5
E6
C12
0.1µF
50V
4
6
8
7
2
5
JP1
3
1
C3
4.7µF
50V
1206
+
C1
22µF
63V
SUNCON
63CE22BS
BURST
PULSE SKIPPING
SPREAD SPECTRUM
SYNC
C10
4.7µF
50V
1206
1. ALL RESISTORS ARE 0603.
ALL CAPACITORS ARE 0603.
4
NOTES: UNLESS OTHERWISE SPECIFIED
GND
TR/SS
SYNC
EN/UV
C11
1µF
50V
0805
FB1
L2
MPZ2012S221AT000 0 2010
4
C7
1µF
C2
4.7µF
50V
1206
C8
0.01µF
VCC
C13
0.1µF
50V
R2
18.2k
(2MHz)
R6
(Opt)
R1
1.00M
3
4
7
3
5
10
9
3
RT
TR/SS
VCC
SYNC
EN/UV
VIN
U1
LT8608EMSE
GND
11
D
5
FB
PG
SW
BST
6
8
2
1
L1
2.2µH
2
R5
187k
49.9k
R3
10pF
C5
1.00M
R4
XFL4020-222MEC
C4
0.22µF
2
VOUT
C6
47µF
10V
1210
1
1
E8
E4
C9 E3
4.7µF
16V
0805
PG
GND
VOUT
5V / 1.5A
A
B
C
D
DEMO MANUAL DC2458A
SCHEMATIC DIAGRAM
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DEMO MANUAL DC2458A
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
8
dc2458af
Linear Technology Corporation
LT 0516 • PRINTED IN USA
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●
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