MAX485 Low Power, Slew-Rate-Limited RS-485/RS-422 Transceiver

Transcription

1 MX485 Low Power, Slew-ate-Limited S-485/S-422 Transceiver DESCIPTION The MX485 is low-power transceivers for S-485 and S-422 communication. IC contains one driver and one receiver. The driver slew rates of the MX485 is not limited, allowing them to transmit up to 2.5Mbps. These transceivers draw between 120µ and 500µ of supply current when unloaded or fully loaded with disabled drivers. ll parts operate from a single 5V supply. Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit. The MX485 is designed for half-duplex applications FETUES Low Quiescent Current: 300µ -7V to +12V Common-Mode Input Voltage ange Three-State Outputs 30ns Propagation Delays, 5ns Skew Full-Duplex and Half-Duplex Versions vailable Operate from a Single 5V Supply llows up to 32 Transceivers on the us Data rate: 2,5 Mbps Current-Limiting and Thermal Shutdown for Driver Overload Protection PPLICTIONS Low-Power S-485 Transceivers Low-Power S-422 Transceivers Level Translators Transceivers for EMI-Sensitive pplications Industrial-Control Local rea Networks ODEING INFOMTION PT NO. Temp. ange ( C) Package MX485CP 0 to 70 8 Pin DIP MX485CS 0 to 70 8 Pin SOP MX485EP -40 to 85 8 Pin DIP MX485ES -40 to 85 8 Pin SOP PINOUT TYPICL PPLICTION O E DE DI TOP VIEW D V CC GND O1 E1 DE1 DI1 D V CC1 GND1 t DIP8 / SOP8 O2 E2 V CC2 t DE2 DI2 D GND2 1

2 PIN DESCIPTIONS Pin No. PIN NME DESCIPTION 01 O eceiver Output. If the receiver output is enabled(e low), then if > by 200mV, O will be high. If < by 200mV, then O will be low. 02 E eceiver Output Enable. low enables the receiver output, O. high input forces the receiver output into a high impedance state. 03 DE Driver Outputs Enable. high on DE enables the driver output. and, and the chip will function as a line driver. low input will force the driver outputs into a high impedance state and the chip will function as a line receiver. 04 DI Driver Input. If the driver outputs are enabled (DE high), then a low on DI forces the outputs low and high. high on DI with the driver outputs enabled will force high and low. 05 GND Ground Connection. 06 Driver Output/eceiver Input. 07 Driver Output/eceiver Input. 08 Vcc Positive Supply; 4.75 < Vcc < SOLUTE MXIMUM TINGS Supply Voltage (V CC )....12V Control Input Voltage...- to (V CC +) Driver Input Voltage (DI) - to (V CC +) Driver Output Voltage (, ).. -8V to +12.5V eceiver Input Voltage (, ). -8V to +12.5V eceiver Output Voltage (O). - to (V CC +) Continuous Power Dissipation. (T = +70 C) 8-Pin Plastic DIP (derate 9.09mW/ C above +70 C)...727mW 8-Pin SO (derate 5.88mW/ C above +70 C) 471mW Storage Temperature ange. -65 C to +160 C Lead Temperature (soldering, 10sec) C DC ELECTICL CHCTEISTICS (V CC = 5V ±5%, T = T MIN to T MX, unless otherwise noted.) (Notes 1, 2) PMETE SYMOL CONDITIONS MIN TYP MX UNITS Differential Driver Output (no load) V OD1 5 V Differential Driver Output (with load) V OD2 = 50Ω (S-422) 2 V = 27Ω (S-485), Figure Change in Magnitude of Driver V OD = 27Ω or 50Ω, Figure V Differential Output Voltage for Complementary Output States Driver Common-Mode Output V OC = 27Ω or 50Ω, Figure 4 3 V Voltage Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States V OD = 27Ω or 50Ω, Figure V Input High Voltage V IH DE, DI, E 2.0 V Input Low Voltage V IL DE, DI, E 0.8 V Input Current I IN1 DE, DI, E ±2 µ Input Current I IN2 DE = ; V IN = 12V 1.0 m (, ) V CC = or 5.25V, V IN = -7V -0.8 eceiver Differential Threshold V TH -7V V CM 12V V Voltage eceiver Input Hysteresis V TH VCM = 70 mv eceiver Output High Voltage V OH IO = -4m, V ID = 200mV 3.5 V eceiver Output Low Voltage V OL IO = 4m, VID = -200mV 0.4 V 2

3 DC ELECTICL CHCTEISTICS (continued) (VCC = 5V ±5%, T = TMIN to TMX, unless otherwise noted.) (Notes 1, 2) MX485 PMETE SYMOL CONDITIONS MIN TYP MX UNITS Three-State (high impedance) I OZ 0.4V V O 2.4V ±1 µ Output Current at eceiver eceiver Input esistance IN -7V V CM 12V 12 kω No-Load Supply Current I CC DE = V CC (Note 3) E = or V CC DE = µ Driver Short-Circuit Current, V O = High I OSD1-7V V O 12V (Note 4) m Driver Short-Circuit Current, m I OSD2-7V V O 12V (Note 4) V O = Low eceiver Short-Circuit Current I OS V O V CC 7 95 m SWITCHING CHCTEISTICS (VCC = 5V ±5%, T = TMIN to TMX, unless otherwise noted.) (Notes 1, 2) PMETE SYMOL CONDITIONS MIN TYP MX UNITS Driver Input to Output t PLH DIFF = 54Ω ns t PHL C L1 = C L2 = 100pF Driver Output Skew to Output t SKEW DIFF = 54Ω, C L1 = C L2 = 100pF 5 10 ns Driver Enable to Output High t ZH C L = 100pF, S2 closed ns Driver Enable to Output Low t ZL C L = 100pF, S1 closed ns Driver Disable Time from Low t LZ C L = 15pF, S1 closed ns Driver Disable Time from High t HZ C L = 15pF, S2 closed ns t PLH - t PHL Differential eceiver Skew t SKD DIFF = 54Ω 13 ns eceiver Enable to Output Low t ZL C L = 15pF, S1 closed ns eceiver Enable to Output High t ZH C L = 15pF, S2 closed ns eceiver Disable Time from t LZ C L = 15pF, S1 closed ns Low eceiver Disable Time from High t HZ C L = 15pF, S2 closed ns Maximum Data ate f MX 2.5 Mbps Note 1: ll currents into device pins are positive; all currents out of device pins are negative. ll voltages are referenced to device ground unless otherwise specified. Note 2: ll typical specifications are given for V CC = 5V and T = +25 C. Note 3: Supply current specification is valid for loaded transmitters when DE =. Note 4: pplies to peak current. See Typical Operating Characteristics. 3

4 TESTING CICUITS V OD V OC ECEIVE OUTPUT TEST POINT C L 15pF 1k S1 S2 1k V CC Figure 1. Driver DC Test Load Figure 2. eceiver Timing Test Load DI DE DIFF C L1 C L2 E 15pF O OUTPUT UNDE TEST 500Ω C L S1 S2 V CC Figure 3. Driver/eceiver Timing Test Circuit Figure 4. Driver Timing Test Load #2 SWITCHING TIME WVEFOMS DI t PLH t PHL 1/2 V O V O V O V O 1/2 VO 10% t r t SKEW 80% V DIFF = V() V() t f t SKEW 90% 20% Figure 5. Driver Propagation Delays DE 5V, V OL t ZL 2. OUTPUT NOMLLY LOW t LZ V OH, t ZH 2. OUTPUT NOMLLY HIGH t HZ Figure 6. Driver Enable and Disable Times 4

5 SWITCHING TIME WVEFOMS V OH V OL t PHL OUTPUT t PLH V OD2, V OD2 INPUT Figure 7. eceiver Propagation Delays E 5V t ZL OUTPUT NOMLLY LOW t LZ t ZH OUTPUT NOMLLY HIGH t HZ Figure 8. eceiver Enable and Disable Times FUNCTION TLES Transmitting INPUTS LINE OUTPUTS E DE DI CONDITION X 1 1 No Fault 0 1 X 1 0 No Fault 1 0 X 0 X X Z Z X 1 X Fault Z Z eceiving INPUTS OUTPUTS E DE V V Inputs Open X Z 5

6 PCKGE DIP8 Package (Narrow.300 Inch) 0.400* (10.160) MX ± 0.015* (6.477 ± 0.381) ( ) ( ) ± (3.302 ± 0.127) ( ) ( ) (1.651) TYP (2.54) SC (3.175) MIN ± (0.457 ± 0.076) (0.508) MIN SOP8 Package (Narrow.150 Inch) * ( ) ( ) ** ( ) ( ) ( ) TYP ( ) ( ) ( ) ( ) TYP (1.270) SC 6