KY485LEEN

KY485LEEN ESD-Enhanced, Fail-safe, Slew-Rate-limited RS-485/RS-422 Transceivers General Description The KY485LEEN +5V, half-duplex, ±20kV ESDprotected RS-485/RS-422-compatible transceivers feature one driver and one receiver. The KY485LEEN include a hot-swap capability to eliminate false transitions on the bus during powerup or live insertion. Features      The KY485LEEN features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free transmission up to 1Mbps. The KY485LEEN feature a 1/8-unit load receiver input impedance, allowing up to 256 transceivers on the bus. These devices are intended for half-duplex communications. All driver outputs are protected to ±20kV ESD using the Human Body Model and ±20kV ESD using the Air-Gap Discharge Model.  +5V Operation Hot-Swappable for Telecom Applications Enhanced Slew-Rate Limiting Facilitates Error-Free Data Transmission Extended ESD Protection for RS-485 I/O Pins ±16kV High fanout driving 1/8Unit load , Allowing up to 256 Transceivers on the Bus. 8 Pin-SO Package Applications      Isolated RS-485 Interfaces Utility Meters Industrial Controls Industrial Motor Drives Automated HVAC Systems TheKY485LEEN is available in an 8-pin SO package. The devices operate over the extended -40°C to +125°C temperature range. Absolute Maximum Ratins (All voltages referenced to GND.) KY485LEEN Supply Voltage VCC...............................................................+6V DE, RE-, DI..............................................................-0.3V to +6 A, B........................................................................... -8V to +13V Short-Circuit Duration (RO, A, B) to GND ..................Continuous Continuous Power Dissipation (TA = +70°C) 8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW Operating Temperature Range ...........................-40°C to +125°C Junction Temperature......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering 10s) ..................................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Package SOIC8 Package Information KY485LEEN Rev.1.0 KEYSEMI Proprietary Information Unauthorized Photocopy and Duplication Prohibited © 2017 KEYSEMI All Rights Reserved KY485LEEN ESD-Enhanced, Fail-safe, Slew-Rate-limited RS-485/RS-422 Transceivers DC Electrical Characteristics (VCC = +5V ± 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) PARAMETER SYMBOL CONDITIONS Differential Driver Output (no load) VOD1 Figure1 Differential Driver Output VOD2 MIN TYP MAX UNITS DRIVER 5 Figure1,R = 50Ω (RS-422) 2.0 Figure1,R = 27Ω (RS-485) 1.5 V V Change in Magnitude of Differential Output Voltage (Note 2) Driver Common-Mode Output Voltage Change In Magnitude of Common-Mode Voltage (Note 2) ∆VOD Figure1,R =50Ωor R= 27Ω 0.2 V VOC Figure1,R=50Ωor R = 27Ω 3 V ∆VOC Figure1,R=50Ωor R = 27Ω 0.2 V Input High Voltage VIH1 DE , DI , RE Input Low Voltage VIL1 DE, DI, RE DI Input Hysteresis VHYS KY485LEEN Input Current IIN1 DE, DI, Input Current (A and B) IIN4 DE = GND, VCC=GND or 5.25V Driver Short-Circuit Output Current (Note 3) VOD1 2.0 V 0.8 100 mV ±2 RE 125 VIN=12V VIN = -7V -7V ≤ VOUT ≤ VCC -75 -250 250 ±25 -7V ≤ VCM ≤ +12V -200 µA µA mA 0V ≤ VOUT ≤ 12V 0V ≤ VOUT ≤ VCC V mA mA RECEIVER Receiver Differential Threshold Voltage VTH Receiver Input Hysteresis ∆VTH Receiver Output High Voltage VOH IO = 4mA, VID = -200mV; Receiver Output Low Voltage VOL IO = -4mA, VID = -50mV 0.4 V Three-State Output Current at Receiver IOZR 0.4V ≤ VO ≤ 2.4V ±1 µA Receiver Input Resistance RIN -7V ≤ VCM ≤ +12V 96 Receiver Output Short-Circuit Current IOSR 0V ≤ VRO ≤ VCC ±7 -125 -50 25 mV mV Vcc-1.5 V kΩ ±95 mA SUPPLY CURRENT Supply Current Supply Current in Shutdown Mode ICC ISHDN No load, DE = VCC 530 900 RE- =DI=GND or VCC DE = GND 500 600 DE = GND, VRE- = VCC 2.5 10 Air Gap Discharge IEC 61000-4-2 ±16 Human Body Model ±8 Human Body Model ±5 µA µA ESD Protection ESD Protection(A,B) ESD Protection(all other pins) KV KV Note 1: All currents into the device are positive; all currents out of the device are negative. All voltages are referred to device KY485LEEN Rev1.0 KEYSEMI CORPORATION 2 KY485LEEN ESD-Enhanced, Fail-safe, Slew-Rate-limited RS-485/RS-422 Transceivers ground unless otherwise noted. Note 2: ∆VOD and ∆VOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 3: Maximum current level applies to peak current just prior to fold-back-current limiting; minimum current level applies during current limiting. Switching Characteristics (VCC = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) PARAMETER SYMBOL tDPLH Driver Input to Output tDPHL Driver Output Skew | tDPLH - tDPHL | CONDITIONS MIN Figures3 and 5, RDIFF = 54Ω, CL1 = CL2 = 100pF 250 1000 250 1000 tDSKEW Figures 3 and 5, RDIFF = 54Ω, CL1 = CL2 = 100pF Driver Rise or Fall Time tDR, tDF Figures 3 and 5, RDIFF = 54Ω, CL1 = CL2 = 100pF Maximum Data Rate fMAX Driver Enable to Output High tDZH Driver Enable to Output Low tDZL Driver Disable Time from Low tDLZ Driver Disable Time from High tDHZ Receiver Input to Output tRPLH, tRPHL | tRPLH - tRPHL | Differential Receiver Skew tRSKD Receiver Enable to Output Low tRZL Receiver Enable to Output High tRZH Receiver Disable Time from Low tRLZ Receiver Disable Time from High tRHZ Time to Shutdown tSHDN Driver Enable from Shutdown to Output High Driver Enable from Shutdown to Output Low Receiver Enable from Shutdown to Output High Receiver Enable from Shutdown to Output Low tDZH(SHDN) tDZL(SHDN) tRZH(SHDN) tRZL(SHDN) TYP MAX 720 ns 720 -3 ns ±100 200 UNITS 530 750 1000 2000 kbps Figures4 and 6, CL = 100pF, S2 closed 2500 ns Figures4 and 6,CL= 100pF, S1 closed 2500 ns 100 ns 100 ns 200 250 ns 3 ±30 ns 20 50 ns 20 50 ns 20 50 ns 20 50 ns 200 600 ns 4500 ns 4500 ns 3500 ns 3500 ns Figures 4 and 6, CL = 15pF, S1 closed Figures 4 and 6, CL = 15pF, S2 closed Figures 7 and 9; | VID | ≥ 2.0V;rise and fall time of VID ≤ 15ns Figures 7 and 9; | VID | ≥ 2.0V;rise and fall time of VID ≤ 15ns Figures 2 and 8, CL = 100pF, S1 closed Figures 2 and 8, CL = 100pF, S2 closed Figures 2 and 8 , CL = 100pF, S1 closed Figures 2 and 8, CL = 100pF, S2 closed (Note 4) Figures 4 and 6, CL = 15pF, S2 closed Figures 4 and 6, CL = 15pF, S1 closed Figures 2 and 8, CL = 100pF, S2 closed Figures 2 and 8, CL = 100pF, S1 closed 50 ns Note 4: The device is put into shutdown by bringing RE high and DE low. If the enable inputs are in this state for less than 50ns, the device is guaranteed not to enter shutdown. If the enable inputs are in this state for at least 600ns, the device is guaranteed to have entered shutdown. KY485LEEN Rev1.0 KEYSEMI CORPORATION 3 KY485LEEN ESD-Enhanced, Fail-safe, Slew-Rate-limited RS-485/RS-422 Transceivers Figure 1 Driver DC Test Load Figure 2 Receiver Enable/Disable Timing Test Load Figure 3 Driver Timing Test Circuit Figure 4 Driver Enable/Disable Timing Test Load Figure 5 Driver Propagation Delays Figure 6 Driver Enable and Disable Times Figure 7 Receiver Propagation Delays Figure 8 Receiver Enable and Disable Times Figure 9 Receiver Propagation Delay Test Circuit KY485LEEN Rev1.0 KEYSEMI CORPORATION 4 KY485LEEN ESD-Enhanced, Fail-safe, Slew-Rate-limited RS-485/RS-422 Transceivers Pin Description PIN NAME FUNCTION 1 RO Receiver Output. When RE is low and if A - B ≥ -50mV, RO will be high; if A - B ≤ -200mV, RO will be low. Receiver Output Enable. Drive RE low to enable RO; RO is high impedance when RE is high. Drive RE high and DE low to enter low-power shutdown mode. RE is a hot-swap input (see the Hot-Swap Capability section for more details). 2 RE 3 DE 4 DI Driver Output Enable. Drive DE high to enable driver outputs. These outputs are high impedance when DE is low. Drive RE high and DE low to enter low-power shutdown mode. DE is a hot-swap input (see the Hot-Swap Capability section for more details). Driver Input. With DE high, a low on DI forces non-inverting output low and inverting output high. Similarly, a high on DI forces non-inverting output high and inverting output low. 5 GND Ground 6 A Non-inverting Receiver Input and Non-inverting Driver Output 7 B Inverting Receiver Input and Inverting Driver Output 8 Vcc Positive Supply, VCC = +5V ±5%. Bypass VCC to GND with a 0.1µF capacitor. Function Table TRANSMITTING INPUTS DE 1 1 0 0 RE X X 0 1 DI 1 0 X X RECEIVING INPUTS RE 0 0 0 1 1 KY485LEEN Rev1.0 DE X X X 1 0 A-B ≥ -0.05V ≤ -0.2V Open/shorted X X KEYSEMI CORPORATION OUTPUTS B/Z 0 1 High-Z Shutdown A/Y 1 0 High-Z OUTPUTS RO 1 0 1 High-Z Shutdown 5 KY485LEEN Applications Information 256 Transceivers on the Bus The standard RS-485 receiver input impedance is 12kΩ (one-unit load), and the standard driver can drive up to 32 unit loads. The KY485LEEN family of transceivers have a 1/8unit-load receiver input impedance (96kΩ), allowing up to 256 transceivers to be connected in parallel on one communication line. Any combination of these devices and/or other RS485 transceivers with a total of 32 unit loads or less can be connected to the line. Low-Power Shutdown Mode Low-power shutdown mode is initiated by bringing both RE- high and DE low. In shutdown, the devices typically draw only 2uA of supply current. RE- and DE may be driven simultaneously; the parts are guaranteed not to enter shutdown if is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown. Reduced EMI and Reflections KY485LEEN is slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. Driver Output Protection Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus contention. The first, a fold-back current limit on the output stage, provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Operating Characteristics). The second, a thermal shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature becomes excessive. Fail-Safe The KY485LEEN guarantees a logic-high receiver output when the receiver inputs are shorted or open, or when they are connected to a terminated transmission line with all drivers disabled. This is done by setting the receiver threshold between -50mV and -200mV. If the differential receiver input voltage (A-B) is greater than or equal to -50mV, RO is logic high. If A-B is less than or equal to -200mV, RO is logic low. In the case of a terminated bus with all transmitters disabled, the receiver’s differential input voltage is pulled to 0V by the termination. With the receiver thresholds of KY485LEEN, this results in a logic high with KY485LEEN Rev1.0 ESD-Enhanced, Fail-safe, Slew-Rate-limited RS-485/RS-422 Transceivers a 50mV minimum noise margin. Unlike previous fail-safe devices, the -50mV to -200mV threshold complies with the ±200mV EIA/TIA485 standard. Hot-Swap Capability When circuit boards are inserted into a hot or powered back plane, differential disturbances to the data bus can lead to data errors. Upon initial circuit-board insertion, the data communication processor undergoes its own powerup sequence. During this period, the processor’s logic-output drivers are high impedance and are unable to drive the DI and RE- inputs of these devices to a defined logic level. Leakage currents up to ±10μA from the highimpedance state of the processor’s logic drivers could cause standard CMOS enable inputs of a transceiver to drift to an incorrect logic level. Additionally, parasitic circuit-board capacitance could cause coupling of VCC or GND to the enable inputs. Without the hot-swap capability, these factors could improperly enable the transceiver’s driver. To overcome both these problems, When VCC rises, an internal power-up signal Turn from low to high and keeps about 20uS then turns to low. During the 20uS high stage, this signal controls the internal logic to force to disable the driver and enable the receiver regardless the state of the DE and RE-. ESD Protection As with all KEYSEMI devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handing and assembly. The driver outputs and receiver inputs of KY485LEEN have extra protection against static electricity. KEYSEMI’s engineers have developed stateof-the-art structures to protect these pins against ESD of ±20kV without damage. The ESD structures withstand high ESD in all states: normal operation shutdown, and powered down. After an ESD event the KY485LEEN keep working without latch-up or damage. ESD protection can be tested in various ways. The transmitter outputs and receiver inputs of the KY485LEEN are characterized for protection to the following limits: ±20kV using the Human Body Model ±20kV using the Air Gap Discharge Method specified in IEC61000-4-2 ESD Test Conditions ESD performance depends on a variety of KEYSEMI CORPORATION 6 KY485LEEN conditions. Contact GIC for a reliability report that documents test setup, test methodology, and test results. Human Body Model Figure 10a shows the Human Body Model, and Figure10b shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5kΩ resistor. IEC 61000-4-2 The IEC 61000-4-2 standard covers ESD testing and performance of finished equipment. However, it does not specifically refer to integrated circuits. The KY485LEEN help you design equipment to meet IEC 61000-4-2 without the need for additional ESD-protection components. The major difference between tests done using the Human Body Model and IEC 61000-4-2 is higher peak current in IEC 61000-4-2 because series resistance is lower in the IEC 61000-42 model. Hence, the ESD withstand voltage measured to IEC 61000-4-2 is generally lower than that measured using the Human Body ESD-Enhanced, Fail-safe, Slew-Rate-limited RS-485/RS-422 Transceivers Model. Figure 10c shows the IEC 61000-4-2 model, and Figure 10d shows the current waveform for IEC61000-4-2 ESD Contact Discharge test. Machine Model The machine model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. The objective is to emulate the stress caused when I/O pins are contacted by handling equipment during test and assembly. Of course, all pins require this protection, not just RS-485 inputs and outputs. The Air-Gap test involves approaching the device with a charged probe. The Contact-Discharge method connects the probe to the device before the probe is energized. Typical Applications The KY485LEEN transceiver is designed for bidirectional data communications on multipoint bus transmission lines. Figure 11 shows typical network applications circuits. To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. Figure 10a Human Body ESD Test Model Figure 10c IEC 61000-4-2 ESD Test Model Figure 10b Human Body Current Waveform Figure 10d IEC 61000-4-2 ESD Current Waveform Figure 11 Typical Half-Duplex RS-485 Network KY485LEEN Rev1.0 KEYSEMI CORPORATION 7 KY485LEEN ESD-Enhanced, Fail-safe, Slew-Rate-limited RS-485/RS-422 Transceivers KY485LEEN Outline Dimension TOP VIEW FRONT VIEW SIDE VIEW KY485LEEN Rev1.0 KEYSEMI CORPORATION 8