Linear Technology DC1973A Quick setup guide

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DEMO MANUAL DC1973A
Description
LT8697
USB 5V 2.5A Output, 42V Input Synchronous
Buck with Cable Drop Compensation
Demonstration circuit 1973A is a USB 5V2.5A 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 applica-
tions. 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.
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.
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.
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.
Whenprobingtheboard,payattentiontoGND and C_GND.
Onthedemonstrationboard,they are connectedtogether 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.
A500mA onboard step load can also be activated to evalu-
ate the load transient response of the circuit. To active the
step load, simply set jumper X5 to V+.
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.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1973A
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DEMO MANUAL DC1973A
Figure 1. LT8697 Demo Circuit EMI Performance, Switching Frequency = 2MHz
Description
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
Quick start proceDure
Demonstration circuit 1973A is easy to set up to evalu-
ate 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. Withpower 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.
performance summary
Specifications are at TA= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Range 6 42 V
VOUT Output Voltage 4.8 5 5.2 V
Max IOUT Maximum Output Current 2.1 A
fSW Switching Frequency 1.9 2 2.05 MHz
EFE Efficiency at DC IOUT = 2.1A, Measured at VOUT 91 %
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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
Required Circuit Components
1 1 C2 Cap., X7R 4.7µF 50V 10% 1206 TAIYO YUDEN, UMK316BJ475KL-T
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
Additional Demo Board Circuit Components
1 1 C1 Cap., Alum 22µF 63V 25% SUN ELECT., 63CE22BS
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
12 1 Q1 Power Mosfet, SOT23 DIODES INC., ZXMN3A14FTA
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
15 1 R11 Res., Chip, 0Ω, 0.25W, 1206 VISHAY, CRCW12060000Z0EA
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
Hardware: For Demo Board Only
1 13 E1-E13 Turret, Testpoint MILL-MAX, 2501-2-00-80-00-00-07-0
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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DEMO MANUAL DC1973A
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
D D C C B B A A
ALL CAPACITORS ARE 0402.
NOTES: UNLESS OTHERWISE SPECIFIED 1. ALL RESISTORS ARE 0402.
(2MHz)
OPEN SET
OPEN
SHORT
OPEN D-
OPEN D+
OPEN
V+
VCABLEVOUT
GND C-GND
DATA+ DATA-
VSYS VCABLE VCABLE
VSYS
VCABLE
VIN
INTVCC
INTVCC
R19
10k
0603
R19
10k
0603
C17 0.1µF 50V C17 0.1µF 50V
C11 1µF 25V 0805 C11 1µF 25V 0805
FB1FB1
E5 C_GND E5 C_GND
R20
2M
0603 R20
2M
0603
R15 75k
0603
R15 75k
0603
C12 1µF 25V 0805 C12 1µF 25V 0805
R9
10k
R9
10k
U1
LT8697EUDD
U1
LT8697EUDD
VIN
5
VIN
6
EN/UV
4
SYNC
1
RCBL
23
ICTRL
24
INTVCC
17
TR/SS
2
RT
3
PGND
7
PGND
8
N/C
9
N/C
12
N/C
11
N/C
10
USB5V 20
PG 19
SYS 18
ISN 22
ISP 21 SW 15 SW 14 SW 13
BST 16
GND
25
C8
4.7µF
50V 1206 C8
4.7µF
50V 1206
E18E18
R21
2
1206
R21
2
1206
E6
GND
E6
GND
X4X4
1
2
3
E17E17
E3
VCABLE 5V / 2.1A
E3
VCABLE 5V / 2.1A
C6 1µF 25V 0603 C6 1µF 25V 0603
E10
ICTRL
E10
ICTRL
C9
OPT
10V
1206 C9
OPT
10V
1206
R8
49.9k
R8
49.9k
R16 43.2k 0603 R16 43.2k 0603
R23
18
2512
R23
18
2512
R14
OPT
R14
OPT
R10 16.5k
0603
R10 16.5k
0603
R17
49.9k
0603
R17
49.9k
0603
C10 0.1µF 25V 0603 C10 0.1µF 25V 0603
C25
47µF
10V 1210 C25
47µF
10V 1210
R1
1M
R1
1M
R18
49.9k 0603
R18
49.9k 0603
R3
0.02
1206
R3
0.02
1206
Q1
ZXMN3A14F
Q1
ZXMN3A14F
1
32
C2 4.7µF 50V
1206
C2 4.7µF 50V
1206
E9 GND E9 GND
E2
GND
E2
GND
X3X3
1
2
3
C16 0.1µF 50V C16 0.1µF 50V
C13 1nFC13 1nF
C14
2.2nF 0603
C14
2.2nF 0603 R24
2
1206
R24
2
1206
E1
VIN
6V - 42V
E1
VIN
6V - 42V
+
C1
22µF
63V
SUNCON
63CE22BS
+
C1
22µF
63V
SUNCON
63CE22BS C3
0.22µF 16V 0603 C3 0.22µF 16V 0603
R22
100k
R22
100k
X1X1
1
2
3
E4
SYNC
E4
SYNC
E8
RCBL
E8
RCBL
C7
4.7uF
50V
1206
C7
4.7uF
50V
1206
R11
0
1206
R11
0
1206
R6
100k
R6
100k
E11
PG
E11
PG
X2X2
1
2
3
R13
OPT 1206
R13
OPT 1206
E15E15
R7
12.4k
0603
R7
12.4k
0603
R4
0.3
0830
2W
R4
0.3
0830
2W
R5
18
2512
R5
18
2512
R2
OPT
R2
OPT
C15 0.1µF 50V C15 0.1µF 50V
E12 GND E12 GND
E16E16
L1
3.3µH
XAL5030-332MEC
L1
3.3µH
XAL5030-332MEC
E7
VOUT
5.xV / 2.1A
E7
VOUT
5.xV / 2.1A
X5X5
1
2
3
E13
VSYS 5.xV / 0.1A
E13
VSYS 5.xV / 0.1A
C4
47µF
10V 1210 C4
47µF
10V 1210
C5 0.1µF C5 0.1µF
J3
USB
J3
USB
1
1
4
43 32 2
U2
LTC6900CS5
U2
LTC6900CS5
V+ 1
OUT 5
GND
2
DIV
4
SET
3
L2
4.7µH
L2
4.7µH
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DEMO MANUAL DC1973A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2013
LT 0713 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LT C ) 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 LT C 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 LT C 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. LT C assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LT C 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 LT C applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
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