Isolated RS485 Interface

Size: px

Start display at page:

Download "Isolated RS485 Interface"

Dortha Stone
5 years ago
Views:

1 Isolated RS485 Interface Functional Diagram ID (A-B) DE RE ISODE R D Mode 200 m L L L H X Receive -200 m L L L L X Receive -7< ID <12 X H X Z X Receive/Drive 1.5 H L H H H Drive -1.5 H L H L L Drive Open L L L H X Receive H = High Level, L = Low Level X = Irrelevant, Z = High Impedance Features +3.3 Input Supply Compatible 2500 RMS Isolation (1 min.) 25 ns Maximum Propagation Delay 35 Mbps Data Rate 1 ns Pulse Skew (typ.) Designed for Multi-point Transmission on Long Bus Lines in Noisy Environments ±60 ma Driver Output Capability Thermal Shutdown Protection Meets or Exceeds ANSI RS-485 and ISO 8482:1987 (E) -40 C to +85 C Temperature Range PROFIBUS International Component Recognition 16-Pin SOIC Package UL1577 Approval Pending IEC Approval Pending Applications Profibus/RS485 Systems Multiple Data Point Transmission Description The IL485 is a galvanically isolated, high-speed differential bus transceiver, designed for bidirectional data communication on balanced transmission lines. Isolation is achieved through patented* Isoloop technology. The IL485 is the first isolated RS485 interface in a standard 16-pin SOIC package that meets the ANSI Standards EIA/TIA-422-B and RS485 and is compatible with 3.3 input supplies. The IL485 has current limiting and thermal shutdown features to protect against output short circuits and bus contention situations that could cause excessive power dissipation. With 1 ns pulse skew and 16 ns propagation delay, the IL485 is ideal for PROFIBUS applications. Isoloop is a registered trademark of NE Corporation. *U.S. Patent number 5,831,426; 6,300,617 and others. RE. J NE Corporation alley iew Road, Eden Prairie, MN Phone: (952) Fax: (952) NE Corporation

2 Absolute Maximum Ratings (11) Parameters Symbol Min. Typ. Max. Units Test Conditions Storage Temperature T S C Ambient Operating Temperature T A C oltage Range at A or B Bus Pins Supply oltage (1) DD1, DD Digital Input oltage -0.5 DD Digital Output oltage -0.5 DD + 1 Continuous Total Power Dissipation C mw C Maximum Output Current I O 95 ma Lead Solder Temperature 260 C 10 sec. ESD 2 k HBM Recommended Operating Conditions Parameters Symbol Min. Typ. Max. Units Test Conditions Supply oltage DD DD Input oltage at any Bus Terminal (separately or common mode) I IC 12-7 High-Level Digital Input oltage IH Low-Level Digital Input oltage IL 0.8 Differential Input oltage (2) ID +12/-7 High-Level Output Current (Driver) I OH -60 ma High-Level Digital Output Current I OH 8 ma (Receiver) Low-Level Output Current (Driver) I OL 60 ma Low-Level Digital Output Current I OL 8 ma (Receiver) Ambient Operating Temperature T A C Digital Input Signal Rise and Fall Times t IR,t IF DC Stable DD1 = 3.3 DD1 = 5.0 Insulation Specifications Parameters Symbol Min. Typ. Max. Units Test Conditions Creepage Distance mm Barrier Impedance > Ω pf Leakage Current 0.2 µa 240 RMS, 60 Hz Safety & Approvals IEC TU Certificate Numbers: Approval Pending Classification: Reinforced Insulation Model Package Pollution Degree Material Group Max. Working oltage IL '' SOIC II III 300 RMS UL 1577 Component Recognition program. File #: Approval Pending Rated 2500 RMS for 1 minute (SOIC) 2

3 IL485 Pin Connections 1 DD1 Input Power Supply 2 GND 1 Input Power Supply Ground Return 3 R Output Data from Bus 4 RE Read Data Enable (if RE is high, R= high impedance) 5 DE Drive Enable 6 D Data Input to Bus 7 NC No Internal Connection 8 GND 1 Input Power Supply Ground Return. 9 GND 2 Output Power Supply Ground Return. 10 ISODE Isolated DE Output for use in Profibus applications where the state of the isolated drive enable node needs to be monitored. 11 NC No Internal Connection 12 A Non-inverting Bus Line 13 B Inverting Bus Line 14 NC No Internal Connection 15 GND 2 Output Power Supply Ground Return. 16 DD2 Output Power Supply 3

4 Driver Section Electrical specifications are T min to T max unless otherwise stated. Parameters Symbol Min. Typ. (5) Max. Units Test Conditions Input Clamp oltage IK -1.5 I L = -18 ma Output voltage O 0 6 I O = 0 Differential Output oltage (2) OD I O = 0 Differential Output oltage (2) OD R L = 54 Ω, DD = 5 Differential Output oltage (2)(6) OD R L = 54 Ω, DD = 4.5 Change in Magnitude of Differential Output oltage (7) OD ±0.2 R L = 54 Ω or 100 Ω 3 Common Mode Output oltage OC -1 R L = 54 Ω or 100 Ω Change in Magnitude of Common Mode Output oltage (7) OC ±0.2 R L = 54 Ω or 100 Ω Output Current (4) 1 Output Disabled I O ma O = O = -7 High Level Input Current I IH 10 µa I = 3.5 Low Level Input Current I IL -10 µa I = 0.4 Short-circuit Output Current I OS mα O = -6 O = 0 O = 8 Supply Current ( DD2 = +5 ) I DD No Load ( DD1 = +5 ) I DD ma (Outputs Enabled) ( DD1 = +3.3 ) I DD Switching Specifications Parameters Symbol Min. Typ. (5) Max. Units Test Conditions Maximum Data Rate 35 Mbps R L = 54 Ω, C L = 50 pf Differential Output Prop Delay t D (OD) ns R L = 54 Ω, C L = 50 pf Pulse Skew (10) t S (P) 1 6 ns R L = 54 Ω, C L = 50 pf Differential Output Rise & Fall Time t T (OD) 8 10 ns R L = 54 Ω, C L = 50 pf Output Enable Time To High Level t PZH ns R L = 54 Ω, C L = 50 pf Output Enable Time To Low Level t PZL ns R L = 54 Ω, C L = 50 pf Output Disable Time From High Level t PHZ ns R L = 54 Ω, C L = 50 pf Output Disable Time From Low Level t PLZ ns R L = 54 Ω, C L = 50 pf Skew Limit (3) t SK (LIM) 2 12 ns R L = 54 Ω, C L = 50 pf Notes: (These apply to both driver and receiver sections) 1. All voltage values are with respect to network ground except differential I/O bus voltages. 2. Differential input/output voltage is measured at the noninverting terminal A with respect to the inverting terminal B. 3. Skew limit is the maximum propagation delay difference between any two devices at 25 C. 4. The power-off measurement in ANSI Standard EIA/TIA-422-B applies to disabled outputs only and is not applied to combined inputs and outputs. 5. All typical values are at DD1, DD2 = 5 or DD1 = 3.3 and T A = 25 C. 6. The minimum OD2 with a 100 Ω load is either ½ OD1 or 2, whichever is greater. 7. OD and OC are the changes in magnitude of OD and OC, respectively, that occur when the input is changed form one logic state to the other. 8. This applies for both power on and power off, refer to ANSI standard RS-485 for exact condition. The EIA/TIA-422-B limit does not apply for a combined driver and receiver terminal. 9. Includes 8 ns read enable time. Maximum propagation delay is 25 ns after read assertion. 10. Pulse skew is defined as the t PLH t PHL of each channel. 4

5 Receiver Section Electrical specifications are T min to T max unless otherwise stated. Parameters Symbol Min. Typ. (5) Max. Units Test Conditions Positive-going Input IT+ 0.2 O = 2.7, Threshold oltage Negative-going Input Threshold oltage IT Hysteresis oltage ( IT+ - IT- ) HYS 60 m High Level Digital Output oltage OH DD ID = 200 m I OH = -20 µa Low Level Digital Output oltage OL 0.2 ID = -200 m I OH = 20 µa High-impedance-state output current I OZ ±20 µa O = 0.4 to ( DD2-0.5) Line Input Current (8) I I -0.8 ma 1 I O = -0.4 ma O = 0.5, I O = 8 ma I = 12 I = -7 Other Input (11) = 0 Input Resistance r I 50 kω Supply Current ( DD2 = +5) I DD No load ( DD1 = +5) ( DD1 = +3.3) I DD1 I DD ma Outputs Enabled Parameters Switching 5 Symbol Min. Typ. (5) Max. Units Test Conditions Maximum Data Rate 35 Mbps R L = 54 Ω, C L = 50 pf Propagation Delay (9) t PD ns O = -1.5 to 1.5, Pulse Skew (10) t SK (P) 1 6 ns C L = 15 pf O = -1.5 to 1.5, C L = 15 pf Skew Limit (3) t SK (LIM) 2 8 ns R L = 54 Ω, C L = 50 pf Output Enable Time To High Level t PZH ns C L = 15 pf Output Enable Time To Low Level t PZL ns C L = 15 pf Output Disable Time From High Level t PHZ ns C L = 15 pf Output Disable Time From Low Level t PLZ ns C L = 15 pf Parameters Switching 3.3 Symbol Min. Typ. (5) Max. Units Test Conditions Maximum Data Rate 35 Mbps R L = 54 Ω, C L = 50 pf Propagation Delay (9) t PD ns O = -1.5 to 1.5, Pulse Skew (10) t SK (P) 2 6 ns C L = 15 pf O = -1.5 to 1.5, C L = 15 pf Skew Limit (3) t SK (LIM) 4 8 ns R L = 54 Ω, C L = 50 pf Output Enable Time to High Level t PZH ns C L = 15 pf Output Enable Time to Low Level t PZL ns C L = 15 pf Output Disable Time from High Level t PHZ ns C L = 15 pf Output Disable Time from Low Level t PLZ ns C L = 15 pf Electrostatic Discharge Sensitivity This product has been tested for electrostatic sensitivity to the limits stated in the specifications. However, NE recommends that all integrated circuits be handled with appropriate care to avoid damage. Damage caused by inappropriate handling or storage could range from performance degradation to complete failure. 5

6 Application Information Power Consumption IsoLoop devices achieve their low power consumption from the manner by which they transmit data across the isolation barrier. By detecting the edge transitions of the input logic signal and converting these to narrow current pulses, a magnetic field is created around the GMR Wheatstone bridge. Depending on the direction of the magnetic field, the bridge causes the output comparator to switch following the input logic signal. Since the current pulses are narrow, about 2.5 ns wide, the power consumption is independent of mark-to-space ratio and solely dependent on frequency. This has obvious advantages over optocouplers whose power consumption is heavily dependent on its onstate and frequency. The approximate power supply current per channel is: I IN = 40 x f x 1 ma f MAX 4 Power Supplies Low ESR capacitors such as ceramic are required to decouple the supplies. Both DD1 and DD2 must be bypassed with 47 nf capacitors. These should be placed as close as possible to DD pins for proper operation. In addition, DD2 should have a 10 µf tantalum capacitor connected in parallel with the 47 nf capacitor. Where f = operating frequency f MAX = 50 MHz IR Soldering Profile 6 NE Corporation alley iew Road Eden Prairie, MN USA Telephone: (952) Fax (952) Internet:

7 0.3'' 16-pin SOIC Package Ordering Information and alid Part Numbers 7 NE Corporation alley iew Road Eden Prairie, MN USA Telephone: (952) Fax (952) Internet:

8 ISB-DS-001-IL485-J Changes 1. Page 1: Revision letter added. 2. Page 1: Ordering Information Removed. 3. Page 2: IEC Reinforced Insulation added. 4. Page 4: Notes added. 5. Page 6: IR Soldering Profile added 6. Page 7: Ordering Information added. 8 NE Corporation alley iew Road Eden Prairie, MN USA Telephone: (952) Fax (952) Internet:

9 About NE An ISO 9001 Certified Company NE Corporation is a high technology components manufacturer having the unique capability to combine spintronic Giant Magnetoresistive (GMR) materials with integrated circuits to make high performance electronic components. Products include Magnetic Field Sensors, Magnetic Field Gradient Sensors (Gradiometer), Digital Magnetic Field Sensors, Digital Signal Isolators and Isolated Bus Transceivers. NE is a leader in GMR research and in 1994 introduced the world s first products using GMR material, a line of GMR magnetic field sensors that can be used for position, magnetic media, wheel speed and current sensing. NE is located in Eden Prairie, Minnesota, a suburb of Minneapolis. Please visit our Web site at or call (952) for information on products, sales or distribution. NE Corporation alley iew Road Eden Prairie, MN USA Telephone: (952) Fax: (952) Internet: isoinfo@nve.com The information provided by NE Corporation is believed to be accurate. However, no responsibility is assumed by NE Corporation for its use, nor for any infringement of patents, nor rights or licenses granted to third parties, which may result from its use. No license is granted by implication, or otherwise, under any patent or patent rights of NE Corporation. NE Corporation does not authorize, nor warrant, any NE Corporation product for use in life support devices or systems or other critical applications without the express written approval of the President of NE Corporation. Specifications shown are subject to change without notice. ISB-DS-001-IL485-J September 29, NE Corporation alley iew Road Eden Prairie, MN USA Telephone: (952) Fax (952) Internet:

Isolated RS485-3V Interface. Features. Applications. Description

Isolated RS485-3V Interface. Features. Applications. Description Isolated RS485-3V Interface Functional Diagram Function Table V ID (A-B) DE RE ISODE R D MODE 0.2V L L L H X Receive 0.2V L L L L X Receive -7