DC1973A - Demo Manual

DEMO MANUAL DC1973A
LT8697
USB 5V 2.5A Output, 42V Input Synchronous
Buck with Cable Drop Compensation
Description
Demonstration circuit 1973A is a USB 5V 2.5A output, 42V
input synchronous buck with cable drop compensation
featuring the LT®8697. The LT8697 is a compact, high
efficiency, high speed synchronous monolithic step-down
switching regulator designed to power 5V USB applications. Top and bottom power switches, compensation
components and other necessary circuits are inside of
the LT8697 to minimize external components and simplify
design. A precise output voltage and programmable cable
drop compensation maintain accurate 5V regulation at the
USB socket at the end of a long cable.
When probing the board, pay attention to GND and C_GND.
On the demonstration board, they are connected together by
default through R13 so a user can connect the ground clip
of a probe to C_GND. However, if a user wants to evaluate
an actual cable, the cable will replace R4 and R13. The
copper between pads of R13 should be cut open. In this
case, C_GND is no longer the same as GND. A differential
measurement is needed to probe across the point of load.
The demonstration board also includes a USB socket.
With the proper configuration of jumpers X1, X2, X3 and
X4, the USB can be configured for different applications.
See Table 1 for configurations.
The circuit runs at 2MHz to minimize external components
size and to avoid AM band. The demo board has an EMI
filter installed. The conducted EMI performance of the
board is shown on Figure 2. The figure shows the circuit
passes the EN55022 Class B with a wide margin.
A 500mA onboard step load can also be activated to evaluate the load transient response of the circuit. To active the
step load, simply set jumper X5 to V+.
When the load current is being drawn from VCABLE, the
load current is limited by the current limit of the LT8697
or by 5.8V limit at VOUT, whichever comes first. The
rated load current of the demonstration circuit is set at
2.1A, enough for all USB applications. If higher voltage or
higher current is needed at VCABLE, refer to application
examples on the data sheet. If VCABLE is not connected
to any load, VOUT can be used to power up a load. VSYS
can also be used to supply a small load.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1973A
The LT8697 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for demo circuit 1973A.
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.
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DEMO MANUAL DC1973A
Description
Figure 1. LT8697 Demo Circuit EMI Performance, Switching Frequency = 2MHz
Table 1. Configure X1 – X4 for Different USB Applications
X1
X2
X3
X4
J3
Do Not Care
Do Not Care
Do Not Care
OPEN
Not in USE
OPEN
OPEN
SHORT
SET
USB - DCP
D+
D-
OPEN
SET
USB - APPLE 2.1A
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DEMO MANUAL DC1973A
Performance Summary
SYMBOL
PARAMETER
VIN
Input Supply Range
Specifications are at TA = 25°C
CONDITIONS
MIN
TYP
6
VOUT
Output Voltage
4.8
Max IOUT
Maximum Output Current
2.1
fSW
Switching Frequency
1.9
EFE
Efficiency at DC
IOUT = 2.1A, Measured at VOUT
5
MAX
UNITS
42
V
5.2
V
A
2
91
2.05
MHz
%
Quick Start Procedure
Demonstration circuit 1973A is easy to set up to evaluate the performance of the LT8697. Refer to Figure 2 and
Figure 3 for proper measurement equipment setup and
follow the procedure below:
1.With power off, connect the input power supply to VIN
and GND.
2.With power off, connect the load to VCABLE and C_GND.
3.Set X1 to X5 to OPEN positions.
4.Turn on the power at the input.
5.Carefully evaluate other design parameters as needed.
6.If a USB device is to be connected to J3, use Table 1 as
a guide to set X1 to X4 for different USB applications.
The total current provided at J3 and VCABLE should
not exceed 2.1A.
7.Set X5 to V+ if a quick transient test is desirable. The
load step applied to VCABLE is 500mA. Again, make
sure the total load current does not exceed 2.1A during
the test.
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DEMO MANUAL DC1973A
Quick Start Procedure
Figure 2. Proper Measurement Equipment Setup
Figure 2. Measure Output Ripple
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DEMO MANUAL DC1973A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Cap., X7R 4.7µF 50V 10% 1206
TAIYO YUDEN, UMK316BJ475KL-T
Required Circuit Components
1
1
C2
2
1
C3
Cap., X5R 0.22µF 16V 10% 0603
TAIYO YUDEN, EMK107BJ224KA-T
3
2
C4, C25
Cap., X7R 47µF 10V 10% 1210
MURATA, GRM32ER71A476KE15L
4
1
C5
Cap., X5R 0.1µF 16V 10% 0402
AVX, 0402YD104KAT2A
5
1
C6
Cap., X7R 1µF 25V 10% 0603
MURATA, GRM188R71E105KA12L
6
1
C13
Cap., X7R 1nF 25V 10% 0402
TDK, C1005X7R1E102K
7
1
R1
Res., Chip 1M 0.06W 1% 0402
VISHAY, CRCW04021M00FKED
8
1
R3
Res., 0.02Ω 0.25W 1% 1206
VISHAY, WSL1206R0200FEA
9
1
R4
Res., Sense, 0.3Ω 2W 1% 0830
SUSUMU, RL7520WT-R30-F
10
2
R6, R22
Res., Chip 100k 0.06W 5% 0402
VISHAY, CRCW0402100KJNED
11
1
R7
Res., Chip 12.4k 0.1W 1% 0603
VISHAY, CRCW060312K4FKEA
12
1
R8
Res., Chip 49.9k 0.06W 1% 0402
VISHAY, CRCW040249K9FKED
13
1
R9
Res., Chip 10k 0.06W 5% 0402
VISHAY, CRCW040210K0JNED
14
1
R10
Res., Chip 16.5k 0.1W 1% 0603
VISHAY, CRCW060316K5FKEA
15
1
U1
I.C., Switching Reg. QFN(24) (UDD) 3MMX5MM
LINEAR TECH., LT8697EUDD#PBF
Cap., Alum 22µF 63V 25%
SUN ELECT., 63CE22BS
Additional Demo Board Circuit Components
1
1
C1
2
1
C7
Cap., X7R 4.7µF 50V 10% 1206
MURATA, GRM31CR71H475KA12L
3
1
C8
Cap., X7R 4.7µF 50V 10% 1206
TAIYO YUDEN, UMK316BJ475KL-T
4
0
C9 (OPT)
Cap., 1206
5
1
C10
Cap., X7R 0.1µF 25V 10% 0603
TDK, C1608X7R1E104K
6
2
C11, C12
Cap., X7R 1µF 25V 10% 0805
TDK, C2012X7R1E105K
7
1
C14
Cap., X7R 2.2nF 10V 10% 0603
AVX 0603ZC222KAT2A
8
3
C15-C17
Cap., X7R 0.1µF 50V 10% 0402
TDK, C1005X7R1H104K
9
1
FB1
Ferrite Bead, 0805
TDK, MPZ2012S221AT
10
1
L1
Inductor, 3.3µH
COILCRAFT, XAL5030-332MEC
11
1
L2
Inductor, 4.7µH
VISHAY, IHLP2020BZER4R7M01
DIODES INC., ZXMN3A14FTA
12
1
Q1
Power Mosfet, SOT23
13
0
R2, R14 (OPT)
Res., 0402
14
2
R5, R23
Res., Power, 18Ω, 1W, 1% 2512
SUSUMU, CPA2512Q18R0FS-T10
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DEMO MANUAL DC1973A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
VISHAY, CRCW12060000Z0EA
15
1
R11
Res., Chip, 0Ω, 0.25W, 1206
16
0
R13
Res., Chip, 1206
17
1
R15
Res., Chip, 75k, 0.1W, 1% 0603
VISHAY, CRCW060375K0FKEA
18
1
R16
Res., Chip, 43.2k, 0.1W, 1% 0603
VISHAY, CRCW060343K2FKEA
19
2
R17, R18
Res., Chip, 49.9k, 0.1W, 1% 0603
VISHAY, CRCW060349K9FKEA
20
1
R19
Res., Chip, 10k, 0.1W, 5% 0603
VISHAY, CRCW060310K0JNEA
21
1
R20
Res., Chip, 2M, 0.1W, 1% 0603
VISHAY, CRCW06032M00FKEA
22
2
R21, R24
Res., Chip, 2Ω, 0.25W, 5% 1206
VISHAY, CRCW12062R00JNEA
23
1
U2
I.C., Oscillator, TSOT-23-S5
LINEAR TECH., LT6900CS5#PBF
Turret, Testpoint
MILL-MAX, 2501-2-00-80-00-00-07-0
Hardware: For Demo Board Only
1
13
E1-E13
2
4
E15-E18
Testpoint, Turret, 0.061"
MILL-MAX, 2308-2-00-80-00-00-07-0
3
5
X1-X5
Headers, Sgl. Row 3 Pins 2mm Ctrs.
SULLINS, NRPN031PAEN-RC
4
5
xX1-xX5
Shunt, 2mm Ctrs.
SAMTEC, 2SN-BK-G
5
1
J3
USB, Right Angle, Receptacle
CnC TECH LLC, 1002-001-01000
6
4
MH1-MH4
Stand-Off, Nylon 0.375"
KEYSTONE, 8832(SNAP ON)
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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
GND
E2
ICTRL
RCBL
GND
SYNC
5
E10
E8
E6
E4
C15
0.1µF
50V
R22
100k
R7
12.4k
0603
4.7µH
C8
4.7µF
50V
1206
L2
+
C6
1µF
25V
0603
INTVCC
C1
22µF
63V
SUNCON
63CE22BS
1. ALL RESISTORS ARE 0402.
ALL CAPACITORS ARE 0402.
NOTES: UNLESS OTHERWISE SPECIFIED
100k
R6
FB1
C7
4.7uF
50V
1206
INTVCC
C16
0.1µF
50V
VIN
4
C5
0.1µF
OPT
R2
C2
4.7µF
50V
1206
R1
1M
R20
2M
0603
R10
16.5k
(2MHz)
0603
C17
0.1µF
50V
3
8
7
3
2
17
24
23
1
4
6
5
SET
PGND
PGND
RT
TR/SS
INTVCC
ICTRL
RCBL
SYNC
EN/UV
VIN
VIN
2
VSYS
OUT
USB5V
PG
SYS
ISN
ISP
SW
SW
SW
X5
5
10k
0603
R19
20
19
18
22
21
15
14
13
16
3
C14
2.2nF
0603
U2
LTC6900CS5
V+
OPEN
3
BST
U1
LT8697EUDD
N/C
E1
N/C
9
GND
25
N/C
11
N/C
12
VIN
6V - 42V
4
1
C3
0.22µF
16V
0603 L1
R5
18
2512
R21
2
1206
R23
18
2512
R24
2
1206
Q1
ZXMN3A14F
VCABLE
R14
OPT
49.9k
R8
3.3µH
C4
XAL5030-332MEC 47µF
10V
1210
3
2
R18
49.9k
0603
R16
43.2k
0603
C25
47µF
10V
1210
2
R17
49.9k
0603
OPEN DX2
3
1
SHORT
R4
E15
VCABLE
1
2
X3
DATA-
DATA+
1
2
3
4
C12
1µF
25V
0805
C11
1µF
25V
0805
1
E11
E9
E7
E5
E3
VCABLE
C10 E13
0.1µF
25V
0603
E12
USB
1
2
3
4
J3
0.3 2W
0830
C-GND
GND
R13
OPT 1206 E17
E18
VCABLE
VOUT
E16
OPEN
OPEN SET
3
1
X4
0.02
1206
R3
VSYS
X1
OPEN D+
3
1
10k
1nF
C9
OPT
10V
1206
R9
C13
R15
75k
0603
0
1206
R11
2
2
10
1
V+
GND
2
2
2
3
1
DIV
4
3
1
5
PG
GND
VOUT
5.xV / 2.1A
C_GND
VCABLE
5V / 2.1A
GND
VSYS
5.xV / 0.1A
A
B
C
D
DEMO MANUAL DC1973A
Schematic Diagram
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DEMO MANUAL DC1973A
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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Linear Technology Corporation
LT 0713 • 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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