Linear DC1957A Quick setup guide

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DEMO MANUAL DC1957A
DESCRIPTION
LTM2892-S
SPI/Digital µModule Isolator
Demonstration circuit 1957A is a serial peripheral inter-
face bus (SPI) or digital µModule isolator featuring the
LTM2892-S. The demo circuit operates from external sup-
ply voltages on VCC1, VL1, VCC2, and VL2. It communicates
all necessary signaling across the isolation barrier through
LTC’s Isolator™ µModule
®
technology.
L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks
and Isolator is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
PERFORMANCE SUMMARY
OPERATING PRINCIPLES
Design files for this circuit board are available at
http://www.linear.com/demo
Specifications are at TA= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VCC1, VCC2 Input Supply Range 3.0 5.5 V
VL1, VL2 Logic Supply Range 1.62 5.5 V
fMAX Maximum Data Rate INx →OUTx, CL= 15pF 20 MHz
SPI Bidirectional Communication
SPI Unidirectional Communication
4
8
MHz
MHz
VIORM Maximum Working Insulation Voltage GND1 to GND2 850 VDC
600 VRMS
Common Mode Transient Immunity 50 kV/µs
The LTM2892-S requires two to four external power sup-
plies for operation, one for power and one for the signal
interface, on each side of the isolation barrier. The logic
supplies may be tied to the input supplies. Isolation is
maintained by the separation of GND1 and GND2 where
significant operating voltages and transients can exist
withoutaffectingtheoperationoftheLTM2892-S.TheON1
and/orON2 pins enable or shut down the LTM2892-S, both
must be driven to their respective logic supply voltage for
proper operation. All SPI or Digital signals are referenced
to the logic supply pins VL1 or VL2.
SPI signaling is typically configured by defining the digital
pins as follows:
Logic Side: IN1 = SCK(IN), IN2 = SDI(IN), IN3 = CS(IN)
= SDOE, and OUTD = SDO(OUT).
Isolated Side: OUT1 = SCK(OUT), OUT2 = SDI(OUT),
OUT3 = CS(OUT), and IND = SDO(IN).
Reference Figure 1 for schematic representation.
No special precautions are required for low RF emissions.
EMI performance is shown in Figure 2, measured using
a gigahertz transverse electromagnetic (GTEM) cell and
method detailed in IEC 61000-4-20, Testing and Measure-
ment Techniques – Emission and Immunity Testing in
Transverse Electromagnetic Waveguides.

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DEMO MANUAL DC1957A
Figure 1. SPI Pin Definition
Figure 2. DC1957A Radiated Emissions
OPERATING PRINCIPLES
VCC1
VL1
ON1
EOUTD
INC
INB
INA
OUTF
OUTE
OUTD
5V
SDO(OUT)
CS(IN)
SDI(IN)
SCK(IN)
5V
SDO(IN)
NOTE: INE AND INF ARE
OPTIONAL CONNECTIONS
CS(OUT)
SDI(OUT)
SCK(OUT)
VCC2
VL2
ON2
EOUTA
OUTC
OUTB
OUTA
INF
INE
IND
LTM2892-S
GND2GND1
ISOLATION BARRIER
dc1957a F01
FREQUENCY (MHz)
0
dBµV/m
60
–20
40
20
0
50
30
10
–10
–30 500 900300 700
dn1957a F02
1000400 800200 600100
TA= 25°C
CISPR 22 CLASS B LIMIT
DUT
DETECTOR = PEAK HOLD
RBW = 120kHz
VBW = 300kHz
SWEEP TIME = 680ms, ≥ 10 SWEEPS
NUMBER OF POINTS = 501

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DEMO MANUAL DC1957A
QUICK START PROCEDURE
Demonstration circuit 1957A is easy to set up and evalu-
ate the performance of the LTM2892-S. Refer to Figure 3
for proper measurement equipment setup and follow the
procedure below.
NOTE: When measuring the input or output voltage ripple
or high speed signals, care must be taken to avoid a long
ground lead on the oscilloscope probe.
1. Install jumpers as shown in Figure 3 and the schematic
diagram.
2. With power off, connect the input power supplies to
VCC1 - GND1 and VCC2 - GND2 as shown.
3. Turn on the power at the input.
NOTE: Make sure that the input voltage does not ex-
ceed6V.
4. Configure jumpers or connect signals to turrets as ap-
propriate. If a signal is connected to an input channel
turret the associated channel jumper must be removed
for proper operation.
Figure 3. Demo Board Setup

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DEMO MANUAL DC1957A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 U1 I.C., LTM2892CY-S LINEAR LTM2892CY-S#PBF
Hardware: For Demo Board Only
2 4 C1-4 CAP., TANT 4.7F 10V 20% 0805 NICHICON F921A475MPA
3 16 E4-19 TURRET, 0.065" MILL-MAX 2308-2-00-80-00-00-07-0
4 6 E1-3, E20-22 TURRET, 0.095" MILL-MAX 2501-2-00-80-00-00-07-0
5 2 JP6-7 2mm SINGLE ROW HEADER, 2 X 1 PIN SAMTEC TMM-102-02-L-S
6 10 JP1-5, JP8-12 2mm SINGLE ROW HEADER, 3 x 1 PIN SAMTEC TMM-103-02-L-S
7 12 JP1-12 2mm SHUNT SAMTEC 2SN-BK-G
8 10 R1-R10 RES., CHIP 100 5% 1206 AAC CR18-101JM
PCB LAYOUT
Top Copper Bottom Copper

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DEMO MANUAL DC1957A
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

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DEMO MANUAL DC1957A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2012
LT 0912 • 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
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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
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