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Instruction Manual for LINEAR TECHNOLOGY models including: DC1079A-A, DC1079A-B, DC1079A-A DC1079A-B Evaluation Board, DC1079A-A DC1079A-B, Evaluation Board, Board
DC1079A-A Analog Devices, Inc. - RADIOMAG GmbH
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DocumentDocumentDEMO MANUAL DC1079A-A/DC1079A-B
LTC4310-1/LTC4310-2 Hot Swappable I2C Isolators
DESCRIPTION
Demonstration circuit 1079A features the LTC4310 I2C isolator. The LTC®4310 provides bidirectional I2C communication between two I2C buses whose grounds are isolated from one another. Each LTC4310 encodes I2C bus logic states into signals that are transmitted across an isolation barrier to another LTC4310. The receiving LTC4310 decodes the transmission and drives its I2C bus to the appropriate logic state. The isolation barrier can be bridged by an inexpensive Ethernet (or other) transformer to achieve communications across voltage differences reaching thousands of volts, or it can be bridged by capacitors for lower voltage isolation. DC1079A shows both transformer and capacitor techniques. Separate supplies are connected on opposite sides of the isolation barrier.
Rise time accelerators provide strong pull-up currents on SCL and SDA rising edges to meet rise time specifications for heavily loaded systems. Data and clock Hot SwapTM circuitry prevent data corruption when a card is inserted into or removed from a live bus. When a bus is stuck low
for 37ms, the LTC4310 turns off its pull-down devices and generates up to sixteen clocks and a STOP bit in an attempt to free the bus. Driving EN low sets the LTC4310 in a very low current shutdown mode to conserve power. This is set with a jumper for each LTC4310 on the DC1079A.
The READY pin provides a digital output flag that pulls low to indicate that the LTC4310 is driving its SDA and SCL pins with the logic state information it is receiving on its RXP and RXN pins from the other LTC4310. An LED at each READY pin indicates that READY is low.
DC1079A-A is populated with the LTC4310-1 and is intended for use in I2C systems up to 100kHz. DC1079A-B is populated with the LTC4310-2 which is intended for I2C bus speeds from 100kHz to 400kHz.
Design files for this circuit board are available at http://www.linear.com/demo
L, LT, LTC, LTM, Hot Swap, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
BOARD PHOTO
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Figure 1. DC1079A
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DEMO MANUAL DC1079A-A/DC1079A-B
PERFORMANCE SUMMARY
Table 1. DC1079A Typical Setup and Performance Summary (TA = 25°C)
PARAMETER
CONDITIONS
Supply and Bus Voltage
VCC_A to GND_A, VCC_B to GND_B, VCC_C to GND_C, VCC_D to GND_D
Isolation Maximum I2C Clock
GND_A to GND_B, 100V Capacitor Coupling GND_C to GND_D, EPF8119S Transformer Coupling
DC1079A-A, LTC4310-1 DC1079A-B, LTC4310-2
Bus Pull-Up Resistors
DC1079A-A, LTC4310-1 DC1079A-B, LTC4310-2
MIN TYP MAX
3
5.5
100 1500
100 400
10 3.3
UNITS
V
V VRMS
kHz kHz
k k
QUICK START PROCEDURE
Demonstration circuit 1079A is easy to set up to evaluate the performance of the LTC4310. Refer to Figure 2 and Figure 3 for proper measurement equipment setup and follow the procedures below.
100V Isolation with Capacitor Coupling (Figure 2):
1. Connect first supply (3V to 5.5V) across VCC_A and GND_A.
2. Connect first I2C bus to SDA_A and SCL_A.
3. Set ENABLE_A Jumper to EN.
4. Connect second supply (3V to 5.5V) across VCC_B and GND_B.
5. Connect second I2C bus to SDA_B and SCL_B.
6. Set ENABLE_B Jumper to EN.
1500VRMS Isolation with Transformer Coupling (Figure 3): 1. Connect first supply (3V to 5.5V) across VCC_C and GND_C. 2. Connect first I2C bus to SDA_C and SCL_C.
3. Set ENABLE_C Jumper to EN.
4. Connect second supply (3V to 5.5V) across VCC_D and GND_D.
5. Connect second I2C bus to SDA_D and SCL_D.
6. Set ENABLE_D Jumper to EN.
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QUICK START PROCEDURE
V1 3V TO 5.5V
ENABLE1 SDA1 SCL1
READY1
DEMO MANUAL DC1079A-A/DC1079A-B
V2 3V TO 5.5V
+
ENABLE2 SDA2 SCL2
READY2
Figure 2. DC1079A Setup for Low Voltage Isolation and Capacitor Coupling
READY1
SCL1 SDA1 ENABLE1
READY2
SCL2 SDA2 ENABLE2
V1 3V TO 5.5V
+
V2 3V TO 5.5V
Figure 3. DC1079A Setup for High Voltage Isolation and Transformer Coupling
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DEMO MANUAL DC1079A-A/DC1079A-B
OPERATION
DC1079A demonstrates I2C communication sent across an isolation barrier with the LTC4310. For low voltage 100V isolation, a power supply between 3V to 5.5V is connected across VCC_A and GND_A. This supply provides the pull-up supply for the I2C bus connected to this side of the ground isolation. A second supply, isolated from the first supply, is connected across VCC_B and GND_B. The second I2C bus is connected to this side and pulled-up to VCC_B.
The state of the I2C bus on GND_A is transmitted by an LTC4310 to the corresponding LTC4310 on GND_B across small 100pF, 100V capacitors. And vice versa, the LTC4310 on GND_B reports its I2C bus state to the LTC4310 on GND_B. When both supplies are up, both LTC4310 devices are enabled (set by jumpers), communication between the two LTC4310 devices is established, and the bus lines are not stuck low, a READY signal is given by each LTC4310. A green LED on each side of the isolation is driven by the respective READY pin and indicates that I2C is linked between the two buses.
In an application with higher voltage isolation of 1500VRMS, an inexpensive Ethernet transformer is used in place of the coupling capacitors. This is demonstrated in the bottom half of the DC1079A. The setup and operation is the same above with the capacitor coupling, but the supplies and I2C buses are connected to GND_C and GND_D ground sides.
DC1079A-A and DC1079A-B DIFFERENCES
On the DC1079A-A, the LTC4310-1 is used at U1, U2, U3, and U4 and intended for bus speeds up to 100kHz. The DC1079A-B uses the LTC4310-2 in all four places instead and is intended for bus speeds from 100kHz to 400kHz. When the SDA (or SCL) bus is rising between 0V and 0.35
· VCC, the LTC4310 controls the bus rise rate to (0.35 · VCC)/900ns for the LTC4310-1 and to (0.35 · VCC)/300ns for the LTC4310-2.
Bus pull-up resistors R2 and R3 that go to VCC_A, R5 and R8 that go to VCC_B, R10 and R11 that go to VCC_C, and R13 and R16 that go to VCC_D are also different between the DC1079A-A and the DC1079A-B. The 10k pull-ups along with the LTC4310-1 on the DC1079A-A allows for approximately 50pF of bus capacitance with a supply of 5V, or 3pF with a 3.3V supply. On the DC1079A-B, the 3.3k pull-ups along with the LTC4310-2 allows for close to 100pF of bus capacitance with a supply of 5Vor 3.3V. Refer to the SDA, SCL Bus Pull-Up Resistor Value Selection section in the LTC4310 datasheet.
RADIATED EMISSIONS
DC1079A capacitor coupling and transformer coupling circuits have been tested and scanned for radiated emissions. The levels fall below the limits defined in the basic international EMI standard CIPR22 Class B. Figure 4 shows the results for the capacitor coupling and Figure 5 is the results for transformer coupling. Layout, parts placement, component selection, and wire connections will all have an effect with radiated emissions. Attention must be paid towards these items when testing for radiated emissions.
BOARD LAYOUT
DC1079A layout provides galvanic isolation on all four layers between the grounds as well as the vias, copper and pads referenced to the respective ground. Refer to the layout files.
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OPERATION
55
DEMO MANUAL DC1079A-A/DC1079A-B
45 35
AMPLITUDE (dBuV/m)
25 15
5
30
100
55
200
300
400
500
600
700
800
FREQUENCY (MHz)
Figure 4. DC1079A, Capacitor Coupling, Radiated Emissions Scan
900
1000
45 35
AMPLITUDE (dBuV/m)
25 15
5
30
100
200
300
400
500
600
700
800
FREQUENCY (MHz)
Figure 5. DC1079A, Transformer Coupling, Radiated Emissions Scan
900
1000
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DEMO MANUAL DC1079A-A/DC1079A-B
PCB LAYOUT
Top Silkscreen
Layer 1. Component Side
6
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Layer 2. GND Layer
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PCB LAYOUT
DEMO MANUAL DC1079A-A/DC1079A-B
Layer 3. GND Layer
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Layer 4. Bottom Layer
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DEMO MANUAL DC1079A-A/DC1079A-B
PARTS LIST
ITEM QTY REFERENCE
DC1079A Rev 3
1
6 C1, C2, C7, C8, C9, C10
2
5 C3, C4, C5, C6, C11
3
4 D1, D2, D3, D4
4
8 E1, E2, E7-E10, E16, E17
5 16 E3-E6, E11-E14, E18-E25
6
4 JP1, JP2, JP5, JP6
7
4 R1, R6, R9, R14
8
1 T1
9
4 XJP1, XJP2X, JP5, XJP6
DC1079A-A Rev 3
1
1
2 12 R2-R5, R7, R8, R10-R13, R16
3
4 U1, U2, U3, U4
DC1079A-B Rev 3
1
1
2
8 R2, R3, R5, R8, R10, R11, R13, R16
3
4 R4, R7, R12, R15
4
4 U1, U2, U3, U4
PART DESCRIPTION
CAP, 0603 0.1F 10V 10% X7R CAP, 0805 100pF 5% 100V COG LED, GREEN TURRET TURRET HEADER, 3-PIN, 2mm RES, 0603 1k 5% 1/10W XFMR, GALVANIC GROUND ISOLATION, 1500V SHUNT, 2mm
PCB ASSEMBLY RES, 0603 10k 5% 1/10W IC, I2C THROUGH SPLITTER
PCB ASSEMBLY RES, 0603 3.3k 5% 1/10W RES, 0603 10k 5% 1/10W IC, I2C THROUGH SPLITTER
MANUFACTURER/PART NUMBER
AVX 0603ZC104KAT AVX 08051A101JAT PANASONIC LN1351C-(TR) MILL-MAX-2501-2-00-80-00-00-07-0 MILL MAX 2308-2-00-80-00-00-07-0 SAMTEC TMM-103-02-L-S AAC CR16-102JM PAC ELEC. EPF8119S SAMTEC 2SN-BK-G
LINEAR TECH DC1079A REV 3 AAC CR16-103JM LINEAR TECH. LTC4310CDD-1
LINEAR TECH DC1079A REV 3 VISHAY CRCW06033K30JNEA AAC CR16-103JM LINEAR TECH. LTC4310CDD-2
8
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SCHEMATIC DIAGRAM
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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.
5
4
VCC_A
E2
D
GND_A
E7
E3 SDA_A SCL_A E5 READY_A E22
GND_A E19
C
A
3
JP1 EN
ENABLE_A
2
DIS
1
VCC_A
R1
R2 R3 R4
1K
[3] [3] 10K
READY_A
D1 GRN
C1
U1
0.1uF
[3]
1 ENABLE 2
SDA 3
SCL 4 READY 5
GND
RXN 10 9
RXP 8
VCC TXP 7
6 TXN
11 GND
3
CAPACITOR ISOLATION
C3 100pF 100V
C4 100pF 100V
C5 100pF 100V
C6 100pF 100V
C11 100pF 100V
2
1
REVISION HISTORY
ECO REV
DESCRIPTION
DATE
APPROVED
3
PRODUCTION
04/08/10
DILIAN R.
VCC_B
E1 VCC_B
3
D
R7 R5 R8 R6
JP2
EN
E8 GND_B
2
ENABLE_B
10K [3] [3] 1K
DIS
1
C2
READY_B
0.1uF U2
[3]
D2 GRN
10 RXN 9 RXP 8 VCC 7 TXP 6 TXN
ENABLE 1 2
SDA 3
SCL READY 4
5 GND
E4 SDA_B E6 SCL_B E23 READY_B
E18 GND_B
11 GND
B C
DEMO MANUAL DC1079A-A/DC1079A-B
E10 VCC_C
E16 GND_C
B
SDA_C
E11
SCL_C
E13
READY_C
E24
GND_C
E20
3
JP5 EN
ENABLE_C
2
DIS
1
VCC_C
R9
R10 R11 R12
1K
[3] [3] 10K
READY_C
D3 GRN
C7
U3
0.1uF
[3]
1 ENABLE 2
SDA 3 SCL 4 READY 5
GND
RXN 10 9
RXP VCC 8 TXP 7
6 TXN
11 GND
C
NOTES: UNLESS OTHERWISE SPECIFIED,
1. ALL CAPACITOR AND RESISTOR CASE SIZE ARE 0603. 2. INSTALL SHUNTS AS SHOWN.
A
[3] ASSY
U1-U4
R2, R3, R5, R8, R10, R11, R13, R16
-A
LTC4310CD-1
10k
-B
LTC4310CD-2
3.3k
5
4
1500 Vrms TRANSFORMER ISOLATION
C9 0.1uF
T1 EPF8119S
1 TD+ 2
CT 3 TD4 N/C 5
N/C 6
RD+ 7 CT(3) 8
RD-
TX+ 16 15
CT(2) TX- 14 N/C 13 12 N/C 11 RX+
CT(4) 10 9
RX-
C10 0.1uF
3
VCC_D
C8
0.1uF U4 [3]
JP6
R15 R13 R16 R14
2
10K [3] [3] 1K
READY_D
D4 GRN
1
EN ENABLE_D DIS
3
E9 VCC_D E17 GND_D
10 RXN 9 RXP 8 VCC 7 TXP 6 TXN
ENABLE 1 2
SDA SCL 3 READY 4
5 GND
B
E12 SDA_D E14 SCL_D E25 READY_D
E21 GND_D
11 GND
D
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DEMO MANUAL DC1079A-A/DC1079A-B
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
10 LinearTechnology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com
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dc1079af LT 0211 · PRINTED IN USA
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