Quad Fault-Protected RS-485/RS-422 Receiver with Fault Detection

Transcription

1 General Description The MX14891E quad fault-protected RS-485/RS-4 receiver is ideal for applications requiring high data rates and reduced noise in rugged environments. Each receiver features a wide common-mode input range of -0V to +0V and is guaranteed to receive data at speeds up to 35Mbps. ll receiver inputs are fault-protected against voltage shorts in the ±40V range. Per-channel fault detection provides warning of irregular conditions, such as short circuits and open connections. The MX14891E is available in a 0-pin TQFN-EP (4mm x 4mm) and operates over the -40 C to +15 C temperature range. pplications Encoder Interfaces Motor Controllers Servo Control Commutation Benefits and Features High Flexibility Simplifies Design Switching Rates up to 35Mbps 1.6V to 5.5V Logic Interface Integrated Fault Detection Reduces Downtime Open-Wire and Short-Circuit Detection Overvoltage and Undervoltage Fault Detection Integrated Protection Ensures Robust Communication ±40V Fault Protection Range ±0V Common Mode Range ±5kV HBM ESD ±7kV ir-gap IEC ESD ±10kV Contact IEC ESD -40 C to +15 C Operating Temperature Range Ordering Information appears at end of data sheet. Typical Operating Circuit 5V 3.3V to 5V ENCODER RS-485/ RS-4 RS-485/ RS-4 B RS-485/ RS-4 Z RS-485/ RS-4 Y 10Ω 10Ω 10Ω 10Ω B B Z Z Y Y VCC Rx RxB RxZ RxY VL O FULT BO BFULT ZO ZFULT YO YFULT 5V 5V 5V 5V SIC MX14891E MOTOR CONTROLLER ; Rev 1; 3/15

2 bsolute Maximum Ratings (ll voltages referenced to GND) VCC V to +6V VL V to (VCC + 0.3V) O, BO, ZO, YO V to (VL + 0.3V) FULT, BFULT, ZFULT, YFULT, V to +6V,, B, B, Z, Z, Y, Y...-40V to +40V Short-Circuit Duration (_O, _FULT to GND)...Continuous Continuous Power Dissipation (T = +70 C) TQFN (derate 5.6mW/ C above +70 C)...051mW Operating Temperature Range C to +15 C Junction Temperature C Storage Temperature Range C to +150 C Lead Temperature (soldering, 10s) C Soldering Temperature (reflow) C Stresses beyond those listed under bsolute 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 Thermal Characteristics (Note 1) Junction-to-mbient Thermal Resistance (θ J )...39 C/W Junction-to-Case Thermal Resistance (θ JC )...6 C/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to Electrical Characteristics (V CC = 5V±10%, V L = 1.6V to V CC, T = -40 C to +15 C, unless otherwise noted. Typical values are at V CC = 5V, V L = 3.3V, T = +5 C.) (Notes, 3) POWER SUPPLY PRMETER SYMBOL CONDITIONS MIN TYP MX UNITS Supply Voltage V CC V Supply Current I CC Outputs not switching, no load 9 14 m Logic Supply Voltage V L V RS-485/RS-4 RECEIVERS (Rx, RxB, RxZ, RxY) Differential Threshold Voltage V TH -0V V CM +0V mv Differential Input Hysteresis ΔV TH -0V V CM +0V 30 mv Single-Ended Input Current I IN V CC = 0V or 5V Low Differential Voltage Fault Threshold V IN = -10V V IN = +10V V TH_DFP -0V V CM +0V, positive V TH_DFN -0V V CM +0V, negative μ mv Maxim Integrated

3 Electrical Characteristics (continued) (V CC = 5V±10%, V L = 1.6V to V CC, T = -40 C to +15 C, unless otherwise noted. Typical values are at V CC = 5V, V L = 3.3V, T = +5 C.) (Notes, 3) PRMETER SYMBOL CONDITIONS MIN TYP MX UNITS Single-Ended Input Fault Threshold V TH_SELP Positive V TH_SELN Negative V LOGIC INTERFCE (O, FULT, BO, BFULT, ZO, ZFULT, YO, YFULT) Output High Voltage V OH O, BO, ZO, YO, I OUT = -3m V L - 0.4V V Output Low Voltage V OL O, BO, ZO, YO, FULT, BFULT, ZFULT, YFULT, I OUT = +3m PROTECTION 0.4 V Thermal-Shutdown Threshold T SHDN Temperature rising +160 C Thermal-Shutdown Hysteresis T HYST 10 C Fault-Protected Input Voltage Range (,, B, B, Z, Z, Y, Y) V IN_F V ESD Protection (,, B, B, Z, Z, DIY, Y) IEC air-gap discharge to GND ±7 IEC contact discharge to GND ±10 Human Body Model ±5 kv ESD Protection (ll Other Pins) Human Body Model ± kv Maxim Integrated 3

4 Switching Characteristics (V CC = 5V±10%, V L = 1.6V to V CC, T = -40 C to +15 C, unless otherwise noted. Typical values are at V CC = 5V, V L = 3.3V, T = +5 C.) (Notes, 3) PRMETER SYMBOL CONDITIONS MIN TYP MX UNITS RECEIVER (Rx, RxB, RxZ, RxY) (Note 4) Maximum Data Rate DR MX 35 Mbps Receiver Propagation Delay t DPLH 5 ns C L = 15pF, V ID = ±3V, Figure 1, Figure t DPHL 5 ns Receiver Propagation Delay Skew t DPLH - t DPHL Receiver Channel-to-Channel Skew t HLSKEW C L = 15pF, V ID = ±3V, Figure 1, Figure 0 5 ns t CSKEW C L = 15pF, V ID = ±3V, Figure 1, Figure 0 8 ns FULT DETECTION (FULT, BFULT, ZFULT) (Note 4) Differential Fault Propagation Delay to _FULT Output ctive Differential Slew Rate to void Fault larm Output Single-Ended Propagation Delay to _FULT Output ctive t DFLH R FULT = 5kW, C FULT = 15pF, Figure 1, Figure 3 R FULT = 5kW, C FULT = 15pF, Figure 1, Figure 3 t SEFLH 970 R FULT = 5kW, C FULT = 15pF t SEFHL μs 1 V/μs Note : ll devices 100% production tested at T = 5 C. Specifications over temperature are guaranteed by design. Note 3: Currents into the device are positive; all currents out of the device are negative. ll voltages are referenced to ground, unless otherwise noted. Note 4: Capacitive load includes test prove and fixture capacitance. μs Maxim Integrated 4

5 Test Circuits and Waveforms VL RFULT CFULT _FULT IN VIN VID Rx _O CL VIN IN Figure 1. Receiver Test Circuit RISE/FLL TIMES ns +3V to +4V VID 0V 0V -3V to -4V VOH _O VCC VCC VOL tplh tphl Figure. Receiver Propagation Delay +3V to +4V FDIFH VID 0V FDIFL -3V to -4V VOH _FULT VCC VCC VOL tdflh tdfhl Figure 3. Fault Detection Timing Maxim Integrated 5

6 Typical Operating Characteristics (VCC = 5V, VL = 3.3V, T = +5 C, unless otherwise noted.) SUPPLY CURRENT (m) PROPGTION DELY vs. TEMPERTURE t PLH t PHL toc01 I CC (m) SUPPLY CURRENT vs. DT RTE Rx and RxB switching, all other inputs are low toc0 V OL (V) _FULT OUTPUT VOLTGE vs. SINK CURRENT _FULT is asserted. toc TEMPERTURE ( C) DT RTE (Mbps) SINK CURRENT (m) LOW DIFFERENTIL INPUT FULT toc RECEIVER OUTPUT VOLTGE LOW vs. SINK CURRENT toc05 6 RECEIVER OUTPUT VOLTGE HIGH vs. SOURCE CURRENT toc06 00mV/div GND V OL (V) V L = 3V V OH (V) V L = 5V V L = 3V 0.15 V L = 5V FULT V/div µs/div SINK CURRENT (m) SOURCE CURRENT (m) COMMON-MODE VOLTGE FULT (HIGH) toc07 COMMON MODE VOLTGE FULT (LOW) toc08 00 RECEIVER DIFFERENTIL THRESHOLD VOLTGE vs. COMMON MODE VOLTGE toc09 GND 150 V OUTN V INSIDE V BCKUP DO 5V/div GND _FULT 5V/div DO 5V/div _FULT 5V/div V TH (mv) HIGH LOW ms/div ms/div COMMON MODE VOLTGE (V) Maxim Integrated 6

7 Pin Configuration TOP VIEW Z V CC O Z FULT *EP ZO 14 N.C. V L BFULT 13 ZFULT MX14891E BO TQFN 4mm 4mm YFULT 11 5 B YO Y Y GND B * EXPOSED PD. CONNECT TO GND. Pin Description PIN NME FUNCTION 1 FULT Open-Drain Fault Output for Receiver. FULT asserts low during a fault condition on Receiver (Rx). See the FULT CONDITION section for more information. N.C. No Connection. Not internally connected. 3 V L Logic Interface Supply Input. V CC must always be greater than or equal to V L. 4 BO Receiver B Output 5 B Non-Inverting Input for Receiver B 6 B Inverting Input for Receiver B 7 GND Ground Maxim Integrated 7

8 Pin Description (continued) PIN NME FUNCTION 8 Y Inverting Input for Receiver Y 9 Y Non-Inverting Input for Receiver Y 10 YO Receiver Y Output 11 YFULT 1 ZFULT Open-Drain Fault Output for Receiver Y. YFULT asserts low during a fault condition on receiver Y. See the FULT CONDITION section for more information. Open-Drain Fault Output for Receiver Z. ZFULT asserts low during a fault condition on receiver Z. See the FULT CONDITION section for more information. 13 BFULT 14 ZO Receiver Z Output Open-Drain Fault Output for Receiver B. BFULT asserts low during a fault condition on receiver B. See the FULT CONDITION section for more information. 15 Z Non-Inverting Input for Receiver Z 16 Z Inverting Input for Receiver Z 17 V CC Supply Input. Bypass V CC to ground through a 0.1μF capacitor as close as possible to the device. V CC must always be greater than or equal to V L. 18 Inverting Input for Receiver 19 Non-Inverting Input for Receiver 0 O Receiver Output EP Exposed Pad. Connect EP to ground. Not intended as the primary ground connection. Maxim Integrated 8

9 Truth Tables Receiver Fault Logic (Rx, RxB, RxZ, RxY) DIFFERENTIL INPUT VOLTGE X = Don t care V ID > +0.45V SINGLE-ENDED INPUT VOLTGE (,, B, B, Z, Z, Y, Y) OUTPUT STTE (O, BO, ZO, YO) _FULT *Receiver operates normally, although thresholds may deviate from limits in the Electrical Characteristics table. FULT CONDITION H H No Fault +0.7V < V ID < +0.45V H Indeterminate Indeterminate -0.V V ID +0.V -0V V SE +0V Indeterminate L Low Differential Input Voltage Fault -0.45V V ID -0.7V L Indeterminate Indeterminate V ID -0.45V L H No Fault X -40V < V SE < -18.5V VLID* L Single-Ended Voltage Fault X -18.5V < V SE < -14.5V VLID* Indeterminate X +14.5V < V SE < +18.5V VLID* Indeterminate Single-Ended Indeterminate Voltage Single-Ended Indeterminate Voltage X +18.5V < V SE < +40V VLID* L Single-Ended Voltage Fault Maxim Integrated 9

10 Detailed Description The MX14891E quad fault-protected RS-485/RS-4 receiver is ideal for applications requiring high data rates and reduced noise in rugged environments. Each receiver features a wide common-mode input range of -0V to +0V and is guaranteed to receive data at speeds up to 35Mbps ll receiver inputs are fault-protected against voltage shorts in the ±40V range. Per-channel fault-detection provides warning of irregular conditions such as short circuits and open connections. Detecting Faults Signal integrity is essential for reliable system operation. Degraded signals could cause problems ranging from simple errors to loss of data. The MX14891E detects common RS-4845/RS-4 faults. These faults include low differential input signals, open-wire, short-circuits, and input voltages that are outside normal operating voltage ranges (below -18V and above +18V). See the Truth Tables for more information. Detecting Small Differential Signals Each receiver on the MX14891E is capable of detecting small DC and C signals. Small DC signals can occur due to open wires or shorts, both of which are explained in the Detecting Short-Circuit and Open-Circuit Faults sections. Small differential C signals can result from either cable attenuation of long or inadequate cables, or due to poor wiring. The fault comparators are high speed and will detect low C signal amplitudes up to 35Mbps Detecting Short-Circuit and Open-Circuit Faults The MX14891E receivers detect short circuits on the inputs. When the and inputs are shorted together, the differential input voltage is 0V, generating a small-signal input voltage fault (Figure 4). Open-circuit detection is similar to detecting a short-circuit condition and relies on the differential termination resistor across the receiver inputs. When an input is open, the termination resistor pulls the non-inverting and inverting inputs to the same voltage, generating a fault condition. The _FULT output asserts when either a short-circuit or open-circuit condition is detected. Thermal Shutdown The MX14891E enters thermal shutdown when the chip temperature rises to above 160 C (typ). Receiver outputs are undefined and the _FULT outputs are off when the device is in thermal shutdown. pplications Information Cable Termination Transmission line termination is required for RS-485/ RS-4 high-speed signals on long cables. 10W termination resistors are commonly used to match the characteristic impedance of the cable. NORML OPERTION Figure 4. Short-Circuit Detection SHORT CIRCUIT TO Maxim Integrated 10

11 Functional Diagram V CC V L MX14891E Rx O FULT B B RxB BO BFULT Z Z RxZ ZO ZFULT Y Y RxY YO YFULT GND Ordering Information PRT TEMP RNGE PIN PCKGE MX14891ETP+ -40 C to +15 C 0 TQFN-EP MX14891ETP+T -40 C to +15 C 0 TQFN-EP +Denotes a lead(pb)-free/rohs-compliant package. T = Tape and reel. *EP = Exposed pad. Chip Information PROCESS: BiCMOS Package Information For the latest package outline information and land patterns (footprints), go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PCKGE TYPE PCKGE CODE OUTLINE NO. LND PTTERN NO. 0 TQFN-EP T044-3C Maxim Integrated 11

12 Revision History REVISION NUMBER REVISION DTE DESCRIPTION PGES CHNGED 0 1/14 Initial release 1 3/15 dded MX14891ETP+ part number and tightened Electrical Characteristics limits. 1-4, 11 For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim Integrated s website at Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. 015 Maxim Integrated Products, Inc. 1