DC1941D - Demo Manual

DEMO MANUAL DC1941D
LTC6820
isoSPI 2-Wire Serial Interface
Description
Demonstration circuit 1941 is an isoSPI™ transceiver
board, based on Linear Technology’s LTC®6820. The
LTC6820 provides a method of interconnecting standard
serial peripheral interface (SPI) devices using a single
twisted pair connection. This proprietary 2-wire interface
is called isoSPI. The LTC6820 encodes SPI signals, up to
1Mbps, into a differential isoSPI signal which is transmitted via a simple pulse transformer through a twisted pair.
At the other end of the twisted pair, the isoSPI signal
can be translated back to SPI (using another LTC6820).
MASTER
SDO
SDI
SCK
CS
Another option would be for the isoSPI to connect to a
Linear Technology device with a built-in isoSPI interface,
such as the LTC6804.
Typically, the LTC6820 will be used in one of two ways:
See Figures 1 and 2.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1941D
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered and isoSPI and QuikEval
are trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
LTC6804
isoSPI PORT
LTC6820
(MASTER)
MSTR
MOSI IP
MISO
SCK
IM
CS
IPA
120Ω
120Ω
IMA
Figure 1. A Single LTC6820 Used to Translate an isoSPI Signal into SPI*
MASTER
µC
SDO
SDI
SCK
CS
REMOTE
SLAVE IC
LTC6820
MSTR
MOSI IP
MISO
SCK
IM
CS
120Ω
LTC6820
MSTR
SDI
SDO
SCK
CS
IP
MOSI
MISO
IM
SCK
CS
120Ω
Figure 2. Two LTC6820 Devices Used to Translate SPI into isoSPI for Long Distance, Isolated Communications
* The isoSPI interface is built into numerous Linear Technology products.
dc1941dfb
1
DEMO MANUAL DC1941D
Overview
The DC1941 enables isoSPI connection using the LTC6820.
As a reference circuit, its combination of galvanic isolation,
common mode filtering, and jumper options enables prototyping of typical applications that employ the LTC6820.
This board provides the foundation for translation between
SPI and isoSPI signals. The SPI Bus is a synchronous serial
data link that uses four single-ended signals to transmit
information over short distances (typically on a single PCB).
SPI devices communicate in master/slave mode, where
the master device initiates the data frame and multiple
slave devices are allowed. Because the LTC6820 includes
a Master and a Slave mode, LTC6820-based conversion
between SPI and isoSPI can occur at the beginning, or
upstream in an isoSPI connection.
Figure 1 shows a typical example with a LTC6820 connected in Master mode. In this example, a DC1941 connects the SPI port of a microcontroller to an isoSPI-based
slave device (such as Linear Technology's LTC6804). In
Figure 2, two DC1941s can be used to translate an endto-end bidirectional SPI interface into an isoSPI interface.
One DC1941 uses Master mode; the other, Slave mode.
This configuration allows the outermost SPI devices to
be galvanically isolated, and enables long distance, noise
immune communication.
The 2-wire isoSPI interface is accessible using standard
RJ45 connectors (J1 on the DC1941). Standard RJ45
connectors allow the use of simple CAT5 cable1 to interconnect isoSPI ports. Other Linear Technology demo
boards with isoSPI also use RJ45 connectors for simple
interconnection. The LTC6820’s four SPI signals are accessible via J2 (14-pin ribbon connector) or JP1 (6-pin
header connector).
The SPI signal can be also translated to a USB signal for
a connection to a PC using Linear Technology's DC2026
(Linduino Interface). The Linduino is connected to the
DC1941 through J2.
Power to the DC1941 can be supplied via the SPI connection (J2, JP1) or the turrets on the board. Typically, the
most convenient method to provide power is to connect
J2, through a 14 pin ribbon cable, to a DC2026 Linduino
board. The Linduino DC2026 sends power on pin 2 of
this connector; it can be 2.5, 3.3, or 5V depending on a
jumper on the DC2026. Whichever voltage is chosen on
the DC2026 will be available at pin 2 of J2, assuming ribbon cable connection.
That said, the DC1941 board, with its LTC6820, does not
require connection to a DC2026. Power can be provided
directly to the DC1941 at turrets from an external source.
In addition, because the VCC and VCCS pins of the LTC6820
do not need to be coupled, one can bring in two distinct
supplies to the DC1941 board. Such a configuration might
be needed if the I/O voltage of the SPI signals differs from
the nominal supply voltage of the LTC6820.
1 A single twisted pair inside the CAT5 is used for the isoSPI
interconnection.
Jumpers
Jumper settings are provided on the DC1941 to configure
the SPI mode, speed and master/slave operation. Jumpers are also provided to configure the isoSPI shutdown
and output power level, as well as power supply options.
2
dc1941dfb
DEMO MANUAL DC1941D
Jumpers
JP2 – VCC to EXT/DC590:
JP7,8 – PHA/POL:
EXT: Set to EXT if the DC1941 is powered from an
external supply. In such a case, power is provided
typically at the turrets on the board.
POL indicates whether SCK idles high (1) or low (0).
PHA indicates latching on the first edge (0) or the second
edge (1).
DC590B (DEFAULT): Set to DC590 if the DC1941 is
powered through the 14-pin ribbon cable connector (J2
on the DC1941). The DC2026 connects to the DC1941
through this 14-pin ribbon cable.
These jumpers set the SPI mode per the following table.
JP3 – EN/SLP_EN:
EN: Set to have the LTC6820 always enabled.
SLP_EN (DEFAULT): When selected, the LTC6820 will
enter shutdown after 4ms of inactivity and will require
a wake up pulse.
JP4 – SLOW/FAST:
SLOW: Set for SPI clock frequencies of 100kHz or less.
FAST (DEFAULT): Set for SPI clock frequencies greater
than 100kHz.
JP5 – MASTER/SLAVE:
The LTC6820 can sit at the start of an SPI connection
when in Master mode. It can alternatively sit at the end
of an isoSPI connection and talk to a slave SPI device
when it is in Slave mode.
MASTER(DEFAULT): Configures the SPI for master
mode; the LTC6820 will operate as the isoSPI master.
When this jumper is set to ‘master’, the J2 connector
should be connected to a SPI master.
SLAVE: Configures the SPI for slave mode; the LTC6820
will operate as an isoSPI slave. The DC1941 should be
connected to a SPI slave device.
JP6 – VCCS to VCC/EXT:
Table 1
MODE
POL
PHA
0
0
0
1
0
1
2
1
0
3 (Default)
1
1
Set to mode 3 for use with LTC6804.
If POL = 0, SCK idles low. Data is latched on the rising
(first) clock edge if PHA = 0 and on the falling (second)
clock edge if PHA = 1.
If POL =1, SCK idles high. Data is latched on the falling
(first) clock edge if PHA = 0 and on the rising (second)
clock edge if PHA = 1.
The two most common configurations are mode 0
(PHA = 0 and POL = 0) and mode 3 (PHA = 1 and POL
= 1) because these modes latch data on a rising clock
edge. For example, in the Default case of mode 3, SCK
normally idles high; the first latching edge is the first
rise after the reset to 0 out of idle.
JP9,10 – VTH1/VTH2:
VTH1: Sets the LTC6820 output drive to 1V, and the
receiver input threshold to 500mV.
VTH2 (DEFAULT): Sets the LTC6820 output drive to 1V,
and the receiver input threshold to 600mV. The VTH2
settings are compatible with other Linear Technology
isoSPI-based demo boards.
VCC (DEFAULT): Sets the LTC6820 SPI input/output
supply voltage (VCCS) to VCC, which sets the SPI logic
levels to VCC.
EXT: Allows the SPI input/output supply (VCCS) to be
connected to a separate voltage from VCC, which allows the logic levels to be set to a different voltage. An
external supply can be connected on the turret labeled
VCCS.
dc1941dfb
3
DEMO MANUAL DC1941D
Setup: DC1941 to isoSPI-Based Demo Board
A single Master mode DC1941 converts SPI to isoSPI.
1.Connect a USB port to DC2026.
2.Connect DC2026 14-pin connector to DC1941 14-pin
connector (J2) with 14-wire ribbon.
3.The DC1941 must be in Master mode (JP5 = Master).
It can take power from the DC2026 (JP2 = DC590).
4.Connect J1 of DC1941 to isoSPI-based demo board
Port A using an Ethernet Patch Cable.
5.Check jumpers on all boards and adjust if necessary.
6.Refer to the Linduino demo manual for software instructions.
Figure 3. Hardware and Jumper Settings to an isoSPI-based Demo Board (Illustrated with the DC1894, LTC6804-1 Demo Board)
4
dc1941dfb
DEMO MANUAL DC1941D
LTC6820 to LTC6804 Setup
Figure 4. Hardware and Jumper Settings to an isoSPI-based Demo Board (Illustrated with the DC1942, LTC6804-2 Demo Board)
Figure 5. (Illustrated with Multiple DC1942, LTC6804-2 Demo Boards) Multidrop Example
dc1941dfb
5
DEMO MANUAL DC1941D
Setup: DC1941 to DC1941 for SPI to SPI with Isolation
The combination of one Master mode DC1941 and one Slave
mode DC1941 enables SPI with isolation using isoSPI.
1.Connect a USB port to DC2026.
2.Connect DC2026 14-pin connector to DC1941 14-pin
connector (J2) with 14-wire ribbon.
3.The DC1941 must be in Master mode (JP5 = Master).
It can take power from the DC2026 (JP2 = DC590).
4.Connect J1 of DC1941 to J1 of a second DC1941 using
an Ethernet Patch Cable.
5.This second DC1941 must be in Slave mode (JP5 =
Slave). It can take power from an external supply (JP2
= EXT).
7.Check jumpers on all boards and adjust if necessary.
8.Refer to the Linduino Demo Manual for software instructions.
If the SPI-based slave board is a Linear Technology demo
board, then it may have the same 14-pin connector. In this
case, this demo board can connect to J2 of the second
DC1941 board. Often engineers will use QuikEval™ software
from Linear Technology when evaluating an SPI-based
demo board. This paradigm remains unchanged when there
is an isoSPI bridge between the DC2026 SPI port and the
SPI-based demo board. QuikEval will operate normally;
a host PC that interfaces with the DC2026 will not know
anything about the isoSPI intermediary physical layer.
6.Connect the SPI of the second DC1941 board to a SPI
slave device.
Figure 6. Hardware and Jumper Settings to Connect Two DC1941s and Add isoSPI Capability to a Standard SPI Slave
6
dc1941dfb
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
AUX
EEGND
EEVCC
EESCL
EESDA
CS
SCK/SCL
MISO
MOSI/SDA
5V
V+
J2
MOLEX, 87831-1420
GND
13
GND
8
GND
3
14
12
10
11
9
6
4
5
7
2
1
5
4
3
2
1
A2
24LC025-I/ST
SDA
WP
SCL
A1
VSS
VCC
5
6
7
8
R19
4.99K
VCC
E1
VCC
2.7V - 5.5V
A0
U2
R18
4.99K
3
2
1
E2
VCC
DC590
JP2
EXT
GND
5
3
1
JP6
3
2
1
1
2
3
1
2
3
JP8
POL
1
0
JP3
8
7
6
5
4
3
2
1
JP7
4
1. ALL CAPACITORS AND RESISTORS ARE 0603.
3
2
1
PHA
VCC
PHA
1
0
C1 0.1uF
VCC
IM
MSTR
CS8
POL
SLOW
SCK
IP
GND
MISO
VCCS
IBIAS
VCMP
MOSI
U1
LTC6820
EN
SLP_EN
EN
ENABLE
E4
0.1uF
C2
VCCS
VCCS
GND
NOTES: UNLESS OTHERWISE SPECIFIED,
EXT
VCC
SPI
JP1
VCC
R3 R4
2K 2K
E3
VCCS
1.5V - 5.5V
VCCS
6
4
2
4
1
R1
1K
R8
60.1
R9
60.1
E6
4
1
3
2
3
2
JP9
4
1
3
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
2
10nF
C49
R11
294
R10
294
JP4
3
2
1
VCC
1
REV
2
SCALE = NONE
DATE:
N/A
SIZE
1
2
3
2
1
DESCRIPTION
R13 0
R12 0
JP5
isoIP
isoIM
1
3
5
7
isoSPI
J1 RJ45
2
4
6
8
Tuesday, February 09, 2016
LTC6820
DEMO CIRCUIT 1941D
1
SHEET 1
isoSPI TWO WIRE SERIAL INTERFACE
IC NO.
DATE
1
OF 1
REV.
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900 www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
R16
0
APPROVED
CUYLER L. 02-09-16
E10
E9
R15
DNS
R14
0
SLAVE
MASTER
1ST PROTO
1
REVISION HISTORY
TECHNOLOGY
T5
CEEH96B
SUMIDA
IM
4
3
IP
SLOW
E8
E7
0
1
__
ECO
CUYLER L. TITLE: SCHEMATIC
AK
APPROVALS
T2
3
2
DLW43SH101XK2
VTH2
VTH1
DLW43SH101XK2
T1
R2
1K
R7
1.2K
CUSTOMER NOTICE
C5 10nF
JP10
VTH1
VTH2
R6
806
VICMP
1
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
APP ENG.
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
9
10
11
12
13
14
15
16
3
2
E5
IBIAS
3
11
12
5
A
B
C
D
DEMO MANUAL DC1941D
Schematic Diagram
dc1941dfb
7
DEMO MANUAL DC1941D
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
dc1941dfb
Linear Technology Corporation
LT 0616 REV B • 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