Datenblatt für DC1903A Demo Manual von Analog Devices Inc.

l ’ LI” DEMO MANUAL DC1903A TECHNOLOGY L7HEWEAR 1
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DEMO MANUAL DC1903A
Description
LTM2889
Isolated CAN µModule
Transceiver Plus Power
Demonstration circuit 1903A is an isolated CAN μModule
®
transceiver plus power featuring the LT M
®
2889. The demo
circuit features an EMI optimized circuit configuration and
printed circuit board layout. All components are integrated
into the μModule isolator. The demo circuit operates from
a single supply on VCC. The part generates an isolated
L, LT, LTC, LTM, Linear Technology, µModule, and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
performance summary
operating principles
output voltage on VCC2 and communicates all necessary
signaling across the isolation barrier through LT C ’s isolator
µModule technology.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1903A
Specifications are at TA = 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VCC Input Supply Range LTM2889-3 3.0 3.3 3.6 V
LTM2889-5 4.5 5.0 5.5 V
VCC2 Regulated Output Voltage ILOAD = 100mA, LTM2889-3
ILOAD = 150mA, LTM2889-5
4.75 5 5.25 V
fMAX Maximum Data Rate 4 Mbps
VIORM Maximum Working Insulation Voltage GND to GND2 560 VDC
400 VRMS
Common Mode Transient Immunity 30 kV/µs
The LTM2889 contains an isolated DC/DC converter that
delivers power to VCC2 at 5V from the input supply VCC.
Isolation is maintained by the separation of GND and GND2
where significant operating voltages and transients can
exist without affecting the operation of the LTM2889. The
logic side ON pin enables or shuts down the LTM2889.
All logic side signals are referenced to the logic supply
pin VL, connected to the input supply voltage VCC. The
LTM2889 is available with two input voltage ranges, 3V
to 3.6V (LTM2889-3) or 4.5V to 5.5V (LTM2889-5). The
isolated side and CAN interface is capable of operating at
3.3V. The VCC2 voltage is jumper selectable for either 5V
or 3.3V operation.
CAN signaling is controlled by the logic input TXD and
the silent pin S. RE controls the RXD output. Connection
to the transceiver pins (CANL and CANH) allows for half-
duplex communication on the isolated side of the demo
circuit. Termination resistors are included on the demo
circuit, with support for split termination to reduce com-
mon mode perturbations.
Data on the TXD input is transmitted differentially on
CANH-CANL when the silent pin (S) is low. Differential
data received on CANH-CANL is delivered at the RXD
output when RE is low. The CAN driver features adjust-
able slew rate via RV1 connected to the RS pin. A jumper
easily allows selection between a fixed fast slew rate and
adjustable rate.
AMPLITUDE mawmu — CISPR 22 CLASS B LINHT — DDVSDBArA DDVSDBArE i I VZUKHZ [IUKHZ SWEEP HME Us *OF POINTS = 5m 0 mo mm 300 400 sun 600 700 800 SDDWDD FREQUENCY WIHZY L7HCUEQB w
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DEMO MANUAL DC1903A
operating principles
Table 1
DEMO CIRCUIT INPUT VOLTAGE DEVICE
DC1903A-A 3V to 3.6V LTM2889-3
DC1903A-B 4.5V to 5.5V LTM2889-5
Demo circuit 1903A is available in two configurations,
supporting both versions of the LTM2889. Table 1 details
the demo circuit configurations.
3. Board/ground plane size has been minimized. This
reduces the dipole antenna formed between the logic
side and isolated side ground planes.
4. Top signal routing and ground floods have been op-
timized to reduce signal loops, minimizing differential
mode radiation.
5. Common mode filtering is integrated into the input and
output pin headers. Filtering helps to reduce emissions
caused by conducted noise and minimizes the effects
of cabling to common mode emissions.
6. A combination of low ESL and high ESR decoupling is
used. A low ESL ceramic capacitor is located close to
the module minimizing high frequency noise conduction.
A high ESR tantalum capacitor is included to minimize
board resonances and prevent voltage spikes due to
hot plugging of the supply voltage.
EMI performance is shown in Figure 1, measured using a
GHz transverse electromagnetic (GTEM) cell and method
detailed in IEC 61000-4-20, testing and measurement
techniques – emission and immunity testing in transverse
electromagnetic waveguides.
The demo circuit has been designed and optimized for low
RF emissions. Some features of the LTM2889 are not avail-
able for evaluation on the demo circuit. The logic supply
voltage VL is tied to VCC, and the ON and RE pins are not
available on the input pin header, but may be controlled
by jumpers JP1 and JP3 respectively. EMI mitigation
techniques used include the following:
1. Four layer PCB, allowing for isolated side to logic side
bridge capacitor. The bridge capacitor is formed between
an inner layer of floating copper which overlaps the logic
side and isolated side ground planes. This structure
creates two series capacitors, each with approximately
0.008” of insulation, supporting the full dielectric with-
stand rating of 2500VRMS. The bridge capacitor provides
a low impedance return path for injected currents due
to parasitic capacitances of the LTM2889’s signal and
power isolating elements.
2. Discrete bridge capacitors (C3, C4) mounted between
GND2 and GND. The discrete capacitors provide ad-
ditional attenuation at frequencies below 400MHz.
Capacitors are safety rated type Y2, manufactured by
Murata, part number GA342QR7GF471KW01L, rated
for 250VRMS.
Figure 1. DC1903A Radiated Emissions
DETECTOR = QPEAK
RBW = 120kHz
VBW = 300kHz
SWEEP TIME = 17s
# OF POINTS = 501
CISPR 22 CLASS B LIMIT
DC1903A–A
DC1903A–B
0
100
200
300
400
500
600
700
800
900
1000
–30
–20
–10
0
10
20
30
40
50
60
AMPLITUDE (dBµV/m)
DC2889a F01
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DEMO MANUAL DC1903A
Quick start proceDure
Figure 2. Demo Board Setup
Demonstration circuit 1903A is easy to set up and evalu-
ate the performance of the LTM2889. Refer to Figure 2
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. Place jumpers in their default positions:
JP1 ON in the ON position
JP2 Silent in the OFF position
JP3 RE in the ON position
JP4 VCC2 in the 5V position
JP5 Slew in the FAST position
JP6 Split in the ON position
JP7 Termination in the ON position
2. With power off, connect the input power supply to VCC
and GND on pin header J1.
3. Turn on the power supply.
NOTE: Make sure that the input voltage does not exceed
6V.
4. Check for the proper output voltage. VCC2 = 5V between
test points V2 and G2.
5. Once the proper output voltages are established, connect
a function generator to terminal TXD and set to square
wave with a low of 0V, high = VCC, termination is Hi-Z.
Set frequency to 500kHz (1Mbps). Enable output of
function generator.
6. Connect oscilloscope to terminal RXD and observe
waveform at 500kHz. This demonstration shows data
that is transmitted from TXD, loops back through CANH
and CANL, and out of RXD.
POWER
SUPPLY
FUNCTION
GENERATOR
OSCILLOSCOPE
VIN
– +
IO 00 0° 0° 0° 0° IO. ;00 IO. L7LJCUEN2
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DEMO MANUAL DC1903A
pcB layout
Layer 2. Ground Plane
Layer 1. Top Layer
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DEMO MANUAL DC1903A
pcB layout
Layer 3. Signal Layer
Layer 4. Bottom Layer
L7 LINE/“2
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DEMO MANUAL DC1903A
parts list
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 U1 -A
-B
IC, LTM2889CY-3
IC, LTM2889CY-5
LINEAR LTM2889CY-3#PBF
LINEAR LTM2889CY-5#PBF
Hardware: For Demo Board Only
1 1 C1, C5 CAP, TANT 10μF 10V 20% TAJA AVX TAJA106M010RNJ
2 1 C2 CAP, CER 1μF 10V 20% 0508 MURATA LLL219R71A105MA01L
3 2 C3, C4 CAP, CER 470pF 250VAC 10% 1808 MURATA GA342QR7GF471KW01L
4 1 J1 0.1” DOUBLE ROW HEADER, 5 × 2 PIN SAMTEC TSW-105-22-G-D
5 1 J1 0.1” FERRITE PLATE, 5 × 2 HOLE FAIR RITE 2644247101
6 1 J2 CON, DSUB 9 PIN FEMALE SINGATRON DR-E9SB-NJ000-S0007
7 6 JP1, JP2, JP3, JP4, JP5,
JP6
HEADER, 2mm, 1 × 3 PIN WURTH 62000311121
8 1 JP7 HEADER, 0.1”, 2 × 3 PIN WURTH 61300621121
9 6 JP1, JP2, JP3, JP4, JP5,
JP6
SHUNT, 2mm WURTH 60800213421
10 1 JP7 SHUNT, 0.1”, 2 × 2 WURTH 60910213421
11 1 R1 RESISTOR, 10kΩ 1% 0805 1/10W VISHAY CRCW080510K0FKEA
12 2 R2, R3 RESISTOR, 60.4Ω 1% 0805 1/10W VISHAY CRCW080560R4FKEA
13 1 R4 RESISTOR, 56.2kΩ 1% 0805 1/10W VISHAY CRCW080556K2FKEA
14 1 R5 RESISTOR, 13kΩ 1% 0805 1/10W VISHAY CRCW080513K0FKEA
15 1 RV1 POTENTIOMETER, 100kΩ, SMT VISHAY TS63Y104KR10
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DEMO MANUAL DC1903A
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
L7 LINE/“2
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DEMO MANUAL DC1903A
Linear Technology Corporation
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© LINEAR TECHNOLOGY CORPORATION 2016
LT 0116 • PRINTED IN USA
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