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Hot-Swappable, Dual I2C Isolators, 5 kV ADuM2250/ADUM2251
FEATURES
Bidirectional I2C communication Open-drain interfaces Suitable for hot-swap applications 30 mA current sink capability 1000 kHz operation 3.0 V to 5.5 V supply/logic levels Wide body, 16-lead SOIC package with >8 mm creepage High temperature operation: 105C Safety and regulatory approvals UL recognition (pending) 5000 V rms for 1 minute per UL 1577 CSA Component Acceptance Notice #5A VDE Certificate of Conformity DIN V VDE V 0884-10 (VDE V 0884-10): 2006-12 VIORM = 846 V peak
GENERAL DESCRIPTION
The ADuM2250/ADUM2251 1 are hot-swappable digital isolators with nonlatching bidirectional communication channels that are compatible with I2C(R) interfaces. This eliminates the need for splitting I2C signals into separate transmit and receive signals for use with standalone optocouplers. The ADuM2250 provides two bidirectional channels supporting a complete isolated I2C interface. The ADUM2251 provides one bidirectional channel and one unidirectional channel for those applications where a bidirectional clock is not required. The ADuM2250/ADUM2251 contain hot-swap circuitry to prevent data glitches when an unpowered card is inserted onto an active bus. These isolators are based on iCoupler(R) chip-scale transformer technology from Analog Devices, Inc. iCoupler is a magnetic isolation technology with performance, size, power consumption, and functional advantages compared to optocouplers. The ADuM2250/ADUM2251 integrate iCoupler channels with semiconductor circuitry to enable a complete, isolated I2C interface in a small form-factor package.
1
APPLICATIONS
Isolated I2C, SMBus, or PMBus Interfaces Multilevel I2C interfaces Power supplies Networking Power-over-Ethernet
Protected by U.S. Patents 5,952,849; 6,873,065; and 7,075,329; other patents pending.
FUNCTIONAL BLOCK DIAGRAMS
GND1 1
16
GND2 NC VDD2 NC SDA2 SCL2 NC GND2
GND1 1
16
GND2 NC VDD2 NC SDA2 SCL2 NC GND2
ADuM2250
NC 2 VDD1 3 NC 4 SDA1 5 SCL1 6 GND1 7 NC 8 NC = NO CONNECT DECODE ENCODE DECODE ENCODE ENCODE DECODE ENCODE DECODE
15
ADUM2251
NC 2 VDD1 3 NC 4 SDA1 5 SCL1 6 GND1 7 NC 8 NC = NO CONNECT DECODE ENCODE ENCODE ENCODE DECODE DECODE
15
14
14
13
13
12
12
11
11
10
10
06670-001
Figure 1. ADuM2250 Functional Block Diagram
Figure 2. ADUM2251 Functional Block Diagram
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2007 Analog Devices, Inc. All rights reserved.
06670-002
9
9
ADuM2250/ADUM2251 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagrams............................................................. 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Electrical Characteristics............................................................. 3 Test Conditions............................................................................. 5 Package Characteristics ............................................................... 6 Regulatory Information............................................................... 6 Insulation and Safety-Related Specifications............................ 6 DIN V VDE V 0884-10 (VDE V 0884-10) Insulation Characteristics ...............................................................................7 Recommended Operating Conditions .......................................7 Absolute Maximum Ratings ............................................................8 ESD Caution...................................................................................8 Pin Configuration and Function Descriptions..............................9 Applications Information .............................................................. 10 Functional Description.............................................................. 10 Startup.......................................................................................... 11 Magnetic Field Immunity............................................................. 11 Outline Dimensions ....................................................................... 13 Ordering Guide .......................................................................... 13
REVISION HISTORY
4/07--Revision 0: Initial Version
Rev. 0 | Page 2 of 16
ADuM2250/ADUM2251 SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
DC Specifications
All voltages are relative to their respective ground. All minimum/maximum specifications apply over the entire recommended operating range, unless otherwise noted. All typical specifications are at TA = 25C, VDD1 = 5 V, and VDD2 = 5 V, unless otherwise noted. Table 1.
Parameter ADuM2250 Input Supply Current, Side 1, 5 V Input Supply Current, Side 2, 5 V Input Supply Current, Side 1, 3.3 V Input Supply Current, Side 2, 3.3 V ADUM2251 Input Supply Current, Side 1, 5 V Input Supply Current, Side 2, 5 V Input Supply Current, Side 1, 3.3 V Input Supply Current, Side 2, 3.3 V LEAKAGE CURRENTS SIDE 1 LOGIC LEVELS Logic Input Threshold1 Logic Low Output Voltages Input/Output Logic Low Level Difference2 SIDE 2 LOGIC LEVELS Logic Low Input Voltage Logic High Input Voltage Logic Low Output Voltage
1 2
Symbol IDD1 IDD2 IDD1 IDD2 IDD1 IDD2 IDD1 IDD2 IISDA1, IISDA2, IISCL1, IISCL2
Min
Typ 2.8 2.7 1.9 1.7 2.8 2.5 1.8 1.6 0.01
Max 5.0 5.0 3.0 3.0 6.0 4.7 3.0 2.8 10
Unit mA mA mA mA mA mA mA mA A
Test Conditions VDD1 = 5 V VDD2 = 5 V VDD1 = 3.3 V VDD2 = 3.3 V VDD1 = 5 V VDD2 = 5 V VDD1 = 3.3 V VDD2 = 3.3 V VSDA1 = VDD1, VSDA2 = VDD2, VSCL1 = VDD1, VSCL2 = VDD2
VSDA1IL, VSCL1IL VSDA1OL, VSCL1OL VSDA1, VSCL1 VSDA2IL, VSCL2IL VSDA2IH, VSCL2IH VSDA2OL, VSCL2OL
500 600 600 50
700 900 850
mV mV mV mV V V mV
ISDA1 = ISCL1 = 3.0 mA
ISDA1 = ISCL1 = 0.5 mA
0.3 x VDD2 0.7 x VDD2 400
ISDA2 = ISCL2 = 30 mA
VIL < 0.5 V, VIH > 0.7 V. VS1L = VS1OL - VS1IL. This is the minimum difference between the output logic low level and the input logic low threshold within a given component. This ensures that there is no possibility of the part latching up the bus to which it is connected.
Rev. 0 | Page 3 of 16
ADuM2250/ADUM2251
AC Specifications
All voltages are relative to their respective ground. All minimum/maximum specifications apply over the entire recommended operating range, unless otherwise noted. All typical specifications are at TA = 25C, VDD1 = 5 V, and VDD2 = 5 V, unless otherwise noted. See Figure 3 for a timing test diagram. Table 2.
Parameter MAXIMUM FREQUENCY OUTPUT FALL TIME 5 V Operation Side 1 Output (0.9 VDD1 to 0.9 V) Side 2 Output (0.9 VDD2 to 0.1 VDD2) 3 V Operation Side 1 Output (0.9 VDD1 to 0.9 V) Side 2 Output (0.9 VDD2 to 0.1 VDD2) PROPAGATION DELAY 5 V Operation Side 1 to Side 2, Rising Edge1 Side 1 to Side 2, Falling Edge2 Side 2 to Side 1, Rising Edge3 Side 2 to Side 1, Falling Edge4 3 V Operation Side 1 to Side 2, Rising Edge1 Side 1 to Side 2, Falling Edge2 Side 2 to Side 1, Rising Edge3 Side 2 to Side 1, Falling Edge4 PULSE-WIDTH DISTORTION 5 V Operation Side 1 -to Side 2, |tPLH12 - tPHL12| Side 2 to Side 1, |tPLH21 - tPHL21| 3 V Operation Side 1 to Side 2, |tPLH12 - tPHL12| Side 2 to Side 1, |tPLH21 - tPHL21| COMMON-MODE TRANSIENT IMMUNITY5
1 2 3
Symbol
Min 1000
Typ
Max
Unit kHz
Test Conditions
4.5 V VDD1, VDD2 5.5 V, CL1 = 40 pF, R1 = 1.6 k, CL2 = 400 pF, R2 = 180 tf1 tf2 13 32 26 52 120 120 ns ns 3.0 V VDD1, VDD2 3.6 V, CL1 = 40 pF, R1 = 1.0 k, CL2 = 400 pF, R2 = 120 tf1 tf2 13 32 32 61 120 120 ns ns 4.5 V VDD1, VDD2 5.5 V, CL1 = CL2 = 0 pF, R1 = 1.6 k, R2 = 180 tPLH12 tPHL12 tPLH21 tPHL21 95 162 31 85 130 275 70 155 ns ns ns ns 3.0 V VDD1, VDD2 3.6 V, CL1 = CL2 = 0 pF, R1 = 1.0 k, R2 = 120 tPLH12 tPHL12 tPLH21 tPHL21 82 196 32 110 125 340 75 210 ns ns ns ns 4.5 V VDD1, VDD2 5.5 V, CL1 = CL2 = 0 pF, R1 = 1.6 k, R2 = 180 PWD12 PWD21 67 54 145 85 ns ns 3.0 V VDD1, VDD2 3.6 V, CL1 = CL2 = 0 pF, R1 = 1.0 k, R2 = 120 PWD12 PWD21 |CMH|, |CML| 114 77 35 215 135 ns ns kV/s
25
tPLH12 propagation delay is measured from the Side 1 input logic threshold to an output value of 0.7 VDD2. tPHL12 propagation delay is measured from the Side 1 input logic threshold to an output value of 0.4 V. tPLH21 propagation delay is measured from the Side 2 input logic threshold to an output value of 0.7 VDD1. 4 tPHL21 propagation delay is measured from the Side 2 input logic threshold to an output value of 0.9 V. 5 CMH is the maximum common-mode voltage slew rate that can be sustained while maintaining VO > 0.8 VDD2. CML is the maximum common-mode voltage slew rate that can be sustained while maintaining VO < 0.8 V. The common-mode voltage slew rates apply to both rising and falling common-mode voltage edges. The transient magnitude is the range over which the common mode is slewed.
Rev. 0 | Page 4 of 16
ADuM2250/ADUM2251
TEST CONDITIONS
GND1 NC VDD1 NC SDA1 SCL1 CL1 CL1 GND1 NC
1 16
GND2 NC VDD2 NC SDA2 SCL2 NC
2
ADuM2250
15
3
14
R1
R1
4
DECODE ENCODE DECODE ENCODE
ENCODE DECODE ENCODE DECODE
13
R2
R2
5
12
6
11
7
10
CL2
CL2
NC = NO CONNECT
Figure 3. Timing Test Diagram
Rev. 0 | Page 5 of 16
06670-005
8
9
GND2
ADuM2250/ADUM2251
PACKAGE CHARACTERISTICS
Table 3.
Parameter Resistance (Input to Output) 1 Capacitance (Input to Output)1 Input Capacitance IC Junction-to-Ambient Thermal Resistance
1
Symbol RI-O CI-O CI JA
Min
Typ 1012 2.2 4.0 45
Max
Unit pF pF C/W
Test Conditions f = 1 MHz Thermocouple located at center of package underside
The device is considered a 2-terminal device; Pin 1 to Pin 8 are shorted together, and Pin 9 to Pin 16 are shorted together.
REGULATORY INFORMATION
The ADuM2250/ADUM2251 is approved by the following organizations. Table 4.
UL (Pending) Recognized under 1577 Component Recognition Program 1 Double insulation, 5000 V rms isolation rating CSA Approved under CSA Component Acceptance Notice #5A Reinforced insulation per CSA 60950-1-03 and IEC 60950-1 600 V rms (848 V peak) maximum working voltage Reinforced insulation per IEC 60601-1 250 V rms (353 V peak) maximum working voltage File 205078 VDE Certified according to DIN V VDE V 0884-10 (VDE V 0884-10): 2006-12 2 Reinforced insulation, 846 V peak
File E214100
1 2
File 2471900-4880-0001
In accordance with UL1577, each ADuM225x is proof tested by applying an insulation test voltage 6000 V rms for 1 second (current leakage detection limit = 10 A). In accordance with DIN V VDE V 0884-10, each ADuM225x is proof tested by applying an insulation test voltage 1590 V peak for 1 sec (partial discharge detection limit = 5 pC). The * marking branded on the component designates DIN V VDE V 0884-10 approval.
INSULATION AND SAFETY-RELATED SPECIFICATIONS
Table 5.
Parameter Rated Dielectric Insulation Voltage Minimum External Air Gap (Clearance) Minimum External Tracking (Creepage) Minimum Internal Gap (Internal Clearance) Tracking Resistance (Comparative Tracking Index) Isolation Group Symbol L(I01) L(I02) Value 5000 7.46 min 8.10 min 0.017 min >175 IIIa Unit V rms mm mm mm V Conditions 1-minute duration Measured from input terminals to output terminals, shortest distance through air Measured from input terminals to output terminals, shortest distance path along body Insulation distance through insulation DIN IEC 112/VDE 0303 Part 1 Material Group (DIN VDE 0110, 1/89, Table 1)
CTI
Rev. 0 | Page 6 of 16
ADuM2250/ADUM2251
DIN V VDE V 0884-10 (VDE V 0884-10) INSULATION CHARACTERISTICS
Note that the * marking on the package denotes DIN V VDE V 0884-10 approval for a 848 V peak working voltage. This isolator is suitable for reinforced isolation only within the safety limit data. Maintenance of the safety data is ensured by protective circuits. Table 6.
Description Installation Classification per DIN VDE 0110 For Rated Mains Voltage 300 V rms For Rated Mains Voltage 450 V rms For Rated Mains Voltage 600 V rms Climatic Classification Pollution Degree (DIN VDE 0110, Table 1) Maximum Working Insulation Voltage Input-to-Output Test Voltage, Method b1 Input-to-Output Test Voltage, Method a After Environmental Tests Subgroup 1 After Input and/or Safety Test Subgroup 2 and Subgroup 3 Highest Allowable Overvoltage Safety-Limiting Values Case Temperature Supply Current Insulation Resistance at TS Conditions Symbol Characteristic I to IV I to II I to II 40/105/21 2 846 1590 Unit
VIORM x 1.875 = VPR, 100% production test, tm = 1 sec, partial discharge < 5 pC VIORM x 1.6 = VPR, tm = 60 sec, partial discharge < 5 pC VIORM x 1.2 = VPR, tm = 60 sec, partial discharge < 5 pC Transient overvoltage, tTR = 10 seconds Maximum value allowed in the event of a failure; see Figure 4 IDD1 + IDD2 VIO = 500 V
VIORM VPR VPR
V peak V peak
1375 1018 VTR 6000
V peak V peak V peak
TS IS RS
150 555 >109
C mA
600
RECOMMENDED OPERATING CONDITIONS
Table 7.
Parameter Operating Temperature Supply Voltages 1 Input/Output Signal Voltage Capacitive Load, Side 1 Capacitive Load, Side 2 Static Output Loading, Side 1 Static Output Loading, Side 2
0 50 100 150 AMBIENT TEMPEARTURE (C) 200
06670-003
SAFE OPERATING VDD1 CURRENT (mA)
500
400
300
200
100
Symbol TA VDD1, VDD2 VSDA1, VSCL1, VSDA2, VSCL2 CL1 CL2 ISDA1, ISCL1 ISDA2, ISCL2
Min -40 3.0
Max +105 5.5 5.5 40 400 3 30
Unit C V V pF pF mA mA
0.5 0.5
0
1
All voltages are relative to their respective ground. See the Applications Information section for data on immunity to external magnetic fields.
Figure 4. Thermal Derating Curve, Dependence of Safety-Limiting Values on Case Temperature, per DIN V VDE V 0884-10
Rev. 0 | Page 7 of 16
ADuM2250/ADUM2251 ABSOLUTE MAXIMUM RATINGS
TA = 25C, unless otherwise noted. Table 8.
Parameter Storage Temperature Ambient Operating Temperature Supply Voltages1 Input/Output Voltage,1 Side 1 Input/Output Voltage,1 Side 2 Average Output Current, per Pin2 Average Output Current, per Pin2 Common-Mode Transients3
1 2
Symbol TST TA VDD1, VDD2 VSDA1, VSCL1 VSDA2, VSCL2 IO1 IO2
Min -65 -40 -0.5 -0.5 -0.5 -18 -100 -100
Max +150 +105 +7.0 VDD1 + 0.5 VDD2 + 0.5 +18 +100 +100
Unit C C V V V mA mA kV/s
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ESD CAUTION
All voltages are relative to their respective ground. See Figure 4 for maximum rated current values for various temperatures. 3 Refers to common-mode transients across the insulation barrier. Commonmode transients exceeding the absolute maximum rating may cause latchup or permanent damage.
Rev. 0 | Page 8 of 16
ADuM2250/ADUM2251 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
GND1* 1 NC 2 VDD1 3 NC 4 SDA1 5 SCL1 6 GND1* 7 NC 8 NC = NO CONNECT
06670-004
16 15
GND2* NC VDD2 NC SDA2 SCL2 NC GND2*
ADuM2250/ ADUM2251
TOP VIEW (Not to Scale)
14 13 12 11 10 9
*PIN 1 AND PIN 7 ARE INTERNALLY CONNECTED. CONNECTING BOTH TO GND1 IS RECOMMENDED. PIN 9 AND PIN 16 ARE INTERNALLY CONNECTED. CONNECTING BOTH TO GND2 IS RECOMMENDED.
Figure 5. Pin Configuration
Table 9. ADuM2250 Pin Function Descriptions
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Mnemonic GND1 NC VDD1 NC SDA1 SCL1 GND1 NC GND2 NC SCL2 SDA2 NC VDD2 NC GND2 Description Ground 1. Ground reference for Isolator Side 1. No Connect. Supply Voltage, 3.0 V to 5.5 V. No Connect. Data Input/Output, Side 1. Clock Input/Output, Side 1. Ground 1. Ground reference for Isolator Side 1. No Connect. Ground 2. Isolated ground reference for Isolator Side 2. No Connect. Clock Input/Output, Side 2. Data Input/Output, Side 2. No Connect. Supply Voltage, 3.0 V to 5.5 V. No Connect. Ground 2. Isolated ground reference for Isolator Side 2.
Table 10. ADUM2251 Pin Function Descriptions
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Mnemonic GND1 NC VDD1 NC SDA1 SCL1 GND1 NC GND2 NC SCL2 SDA2 NC VDD2 NC GND2 Description Ground 1. Ground reference for Isolator Side 1. No Connect. Supply Voltage, 3.0 V to 5.5 V. No Connect. Data Input/Output, Side 1. Clock Input, Side 1. Ground 1. Ground reference for Isolator Side 1. No Connect. Ground 2. Isolated ground reference for Isolator Side 2. No Connect. Clock Output, Side 2. Data Input/Output, Side 2. No Connect. Supply Voltage, 3.0 V to 5.5 V. No Connect. Ground 2. Isolated ground reference for Isolator Side 2.
Rev. 0 | Page 9 of 16
ADuM2250/ADUM2251 APPLICATIONS INFORMATION
FUNCTIONAL DESCRIPTION
The ADuM2250/ADUM2251 interface on each side to I2C signals. Internally, the bidirectional I2C signals are split into two unidirectional channels communicating in opposite directions via dedicated iCoupler isolation channels. One channel of each pair (the Side 1 input of each I/O pin in Figure 6) implements a special input buffer and output driver that can differentiate between externally generated inputs and its own output signals. It only transfers externally generated input signals to the corresponding Side 2 data or clock pin. Both the Side 1 and the Side 2 I2C pins are designed to interface to an I2C bus operating in the 3.0 V to 5.5 V range. A logic low on either side causes the corresponding I/O pin across the coupler to be pulled low enough to comply with the logic low threshold requirements of other I2C devices on the bus. Bus contention and latch-up is avoided by guaranteeing that the input low threshold at SDA1 or SCL1 is at least 50 mV less than the output low signal at the same pin. This prevents an output logic low at Side 1 being transmitted back to Side 2 and pulling down the I2C bus by latching the state. Because the Side 2 logic levels/thresholds and drive capabilities comply fully with standard I2C values, multiple ADuM2250/ ADUM2251 devices connected to a bus by their Side 2 pins can communicate with each other and with other devices having I2C compatibility as shown in Figure 7. Note the distinction between I2C compatibility and I2C compliance. I2C compatibility refers to situations in which the logic levels or drive capability of a component do not necessarily meet the requirements of the I2C specification but still allow the component to communicate with an I2C-compliant device. I2C compliance refers to situations in which the logic levels and drive capability of a component fully meet the requirements of the I2C specification. Because the Side 1 pin has a modified output level/input threshold, Side 1 of the ADuM2250/ADUM2251 can only communicate with devices fully compliant with the I2C standard. In other words, Side 2 of the ADuM2250/ADUM2251 is I2C-compliant while Side 1 is only I2C-compatible. The Side 1 I/O pins must not be connected to other I2C buffers that implement a similar scheme of dual I/O threshold detection. This latch-up prevention scheme is implemented in several popular I2C level shifting and bus extension products currently available from Analog Devices and other manufacturers. Care should be taken to review the data sheet of potential I2C bus buffering products to ensure that only one buffer on a bus segment implements a dual threshold scheme. A bus segment is a portion of the I2C bus that is isolated from other portions of the bus by galvanic isolation, bus extenders, or level shifting buffers. Table 11 shows how multiple ADuM2250/ ADUM2251 components can coexist on a bus as long as two Side 1 buffers are not connected to the same bus segment. Table 11. ADuM225x Buffer Compatibility
Side 1 Side 2 Side 1 No Yes Side 2 Yes Yes
The output logic low levels are independent of the VDD1 and VDD2 voltages. The input logic low threshold at Side 1 is also independent of VDD1. However, the input logic low threshold at Side 2 is designed to be at 0.3 VDD2, consistent with I2C requirements. The Side 1 and Side 2 I/O pins have open-collector outputs whose high levels are set via pull-up resistors to their respective supply voltages.
GND1 NC VDD1 NC SDA1 SCL1 GND1 NC
1 16
GND2 NC VDD2 NC SDA2 SCL2 NC GND2
06670-006
2
ADuM2250
15
3
14
4
DECODE ENCODE DECODE ENCODE
ENCODE DECODE ENCODE DECODE
13
5
12
6
11
7
10
8
9
SYMBOL INDICATES A DUAL THRESHOLD INPUT BUFFER. NC = NO CONNECT
Figure 6. ADuM2250 Block Diagram
I2C BUS
1 2 16
CPU OR SECONDARY BUS SEGMENT
VDD1 SDA1 SCK1 GND1
ADuM2250
15 14 13 12 11 10 9
3 4 5 6 7 8
VDD2 SDA2 SCK2
06670-007
GND2
Figure 7. Typical Isolated I2C Interface Using ADuM2250
Rev. 0 | Page 10 of 16
ADuM2250/ADUM2251
STARTUP
Both the VDD1 and VDD2 supplies have an under voltage lockout feature that prevents the signal channels from operating unless certain criteria is met. This feature is to avoid the possibility of input logic low signals from pulling down the I2C bus inadvertently during power-up/power-down. Criteria that must be met for the signal channels to be enabled are as follows: * * Both supplies must be at least 2.5 V. At least 40 s must elapse after both supplies exceed the internal start-up threshold of 2.0 V. The pulses at the transformer output have an amplitude greater than 1.0 V. The decoder has a sensing threshold at about 0.5 V, therefore establishing a 0.5 V margin in which induced voltages can be tolerated. The voltage induced across the receiving coil is given by
V = (-d / dt ) rn2 ; n = 1, 2, ... N
where: is the magnetic flux density (gauss). rn is the radius of the nth turn in the receiving coil (cm). N is the number of turns in the receiving coil. Given the geometry of the receiving coil in the ADuM2250/ ADUM2251 and an imposed requirement that the induced voltage be at most 50% of the 0.5 V margin at the decoder, a maximum allowable magnetic field is calculated, as shown in Figure 10.
100
Until both of these criteria are met for both supplies, the ADuM2250/ADUM2251 outputs are pulled high thereby ensuring a startup that avoids any disturbances on the bus. Figure 8 and Figure 9 illustrate the supply conditions for fast and slow input supply slew rates.
MAXIMUM ALLOWABLE MAGNETIC FLUX DENSITY (kgauss)
10
MINIMUM RECOMMENDED OPERATING SUPPLY, 3.0V SUPPLY VALID MINIMUM VALID SUPPLY, 2.5V INTERNAL STARTUP THRESHOLD, 2.0V
06670-008
1
0.1
0.01
40s
Figure 8. Start-Up Condition, Supply Slew Rate < 12.5 V/ms
10k 1M 10M 100k MAGNETIC FIELD FREQUENCY (Hz)
100M
Figure 10. Maximum Allowable External Magnetic Flux Density
MINIMUM RECOMMENDED OPERATING SUPPLY, 3.0V SUPPLY VALID MINIMUM VALID SUPPLY, 2.5V INTERNAL STARTUP THRESHOLD, 2.0V
06670-009
40s
Figure 9. Start-Up Condition, Supply Slew Rate > 12.5 V/ms
For example, at a magnetic field frequency of 1 MHz, the maximum allowable magnetic field of 0.2 kgauss induces a voltage of 0.25 V at the receiving coil. This is about 50% of the sensing threshold and does not cause a faulty output transition. Similarly, if such an event were to occur during a transmitted pulse (and had the worst-case polarity), it would reduce the received pulse from >1.0 V to 0.75 V (still well above the 0.5 V sensing threshold of the decoder).
MAGNETIC FIELD IMMUNITY
The ADuM2250/ADUM2251 are extremely immune to external magnetic fields. The limitation on the magnetic field immunity of the ADuM2250/ADUM2251 is set by the condition in which induced voltage in the receiving coil of the transformer is sufficiently large to either falsely set or reset the decoder. The following analysis defines the conditions under which this may occur. The 3 V operating condition of the ADuM2250/ADUM2251 is examined because it represents the most susceptible mode of operation.
Rev. 0 | Page 11 of 16
06670-010
0.001 1k
ADuM2250/ADUM2251
MAXIMUM ALLOWABLE CURRENT (kA)
The preceding magnetic flux density values correspond to specific current magnitudes at given distances away from the ADuM2250/ADUM2251 transformers. Figure 11 expresses these allowable current magnitudes as a function of frequency for selected distances. As seen, the ADuM2250/ADUM2251 is extremely immune and can be affected only by extremely large currents operated at high frequency and very close to the component. For the 1 MHz example, place a 0.5 kA current 5 mm away from the ADuM2250/ADUM2251 to affect the operation of the component. Note that at combinations of strong magnetic fields and high frequencies, any loops formed by printed circuit board traces could induce sufficiently large error voltages to trigger the threshold of succeeding circuitry. Care should be taken in the layout of such traces to avoid this possibility.
1000 DISTANCE = 1m 100
10 DISTANCE = 100mm 1 DISTANCE = 5mm 0.1
1k
10k
100k
1M
10M
100M
MAGNETIC FIELD FREQUENCY (Hz)
Figure 11. Maximum Allowable Current for Various Current-to-ADuM2250/ADUM2251 Spacings
Rev. 0 | Page 12 of 16
06670-011
0.01
ADuM2250/ADUM2251 OUTLINE DIMENSIONS
10.50 (0.4134) 10.10 (0.3976)
16 9
7.60 (0.2992) 7.40 (0.2913)
1 8
10.65 (0.4193) 10.00 (0.3937)
1.27 (0.0500) BSC 0.30 (0.0118) 0.10 (0.0039) COPLANARITY 0.10 0.51 (0.0201) 0.31 (0.0122)
2.65 (0.1043) 2.35 (0.0925)
0.75 (0.0295) 0.25 (0.0098)
8 0 0.33 (0.0130) 0.20 (0.0079)
45
SEATING PLANE
1.27 (0.0500) 0.40 (0.0157)
COMPLIANT TO JEDEC STANDARDS MS-013- AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 12. 16-Lead Standard Small Outline Package [SOIC_W] Wide Body (RW-16) Dimensions shown in millimeters (inches)
ORDERING GUIDE
Model ADuM2250ARWZ 1 ADuM2250ARWZ-RL1 ADUM2251ARWZ1 ADUM2251ARWZ-RL1
1
Number of Inputs, VDD1 Side 2 2 2 2
Number of Inputs, VDD2 Side 2 2 1 1
Maximum Data Rate (Mbps) 1 1 1 1
Temperature Range -40C to +105C -40C to +105C -40C to +105C -40C to +105C
030707-B
Package Description 16-Lead SOIC_W 16-Lead SOIC_W, 13" Reel 16-Lead SOIC_W 16-Lead SOIC_W, 13" Reel
Package Option RW-16 RW-16 RW-16 RW-16
Z = RoHS Compliant Part.
Rev. 0 | Page 13 of 16
ADuM2250/ADUM2251 NOTES
Rev. 0 | Page 14 of 16
ADuM2250/ADUM2251 NOTES
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ADuM2250/ADUM2251 NOTES
(c)2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06670-0-4/07(0)
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