Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsInterface ICsInterface IC - transceivers RS422, RS485 1/1 SOIC 8 N

+5.0V, ±30kV ESD-Protected, Fail-Safe,

Hot-Swap, RS-485/RS-422 Transceiver

MAX14780E

19-5652; Rev 3; 1/15

General Description

The MAX14780E is a +5V, ±30kV HBM ESD half duplex

RS-485/422 transceiver.

The MAX14780E features reduced slew-rate drivers that

minimize EMI and reduce reflections caused by improp-

erly terminated cables, allowing error-free data transmis-

sion up to 500kbps.

The MAX14780E is available in an 8-pin SO and PDIP

packages operating over a temperature range from

-40°C to +85°C.

Applications

Utility Meters

Lighting Systems

Industrial Control

Telecom

Security Systems

Instrumentation

Benefits and Features

Integrated Protection Increases Robustness

S ±30kV HBM ESD per JEDEC JS-001-2012

S ±12kV Contact ESD per IEC 61000-4-2

S ±15kV Air Gap ESD per IEC 61000-4-2

S True Fail-Safe Receiver Prevents False

Transitions on Receiver Input Short or Open

S Hot Swap Eliminates False Transitions During

Power-Up or Hot Insertion

S Short-Circuit Protected Outputs Low Current

Reduces Power Consumption

Low Current Reduces Power Consumption

S 10µA Shutdown Current

S 1.2mA of Supply Current When Unloaded

Ordering Information

+Denotes a lead(Pb)-free/RoHS-compliant package.

Typical Operating Circuit

0.1µF

TYPICAL HALF-DUPLEX OPERATING CIRCUIT

GND

MAX14780E

PART TEMP RANGE PIN-PACKAGE

MAX14780EESA+

-40NC to +85NC

8 SO

MAX14780EEPA+

-40NC to +85NC

8 PDIP

For pricing, delivery, and ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

Summary of content (14 pages)

PAGE 1
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver General Description The MAX14780E is a +5V, ±30kV HBM ESD half duplex RS-485/422 transceiver. The MAX14780E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 500kbps. The MAX14780E is available in an 8-pin SO and PDIP packages operating over a temperature range from -40°C to +85°C.
PAGE 2
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) Supply Voltage (VCC)............................................................ +6V Control Input Voltage (RE, DE)................................-0.3V to +6V Driver Input Voltage (DI)..........................................-0.3V to +6V Driver Output Voltage (A, B).....................................-8V to +13V Receiver Input Voltage (A, B)......................
PAGE 3
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver DC ELECTRICAL CHARACTERISTICS (continued) (VCC = +5.0V ±10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5.0V and TA = +25NC.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP VCC 0.6 MAX UNITS RO Output-High Voltage VOH IO = -1mA V RO Output-Low Voltage VOL IO = 1mA 0.
PAGE 4
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver RECEIVER SWITCHING CHARACTERISTICS WITH INTERNAL SRL (500kbps) (VCC = +5.0V ±10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5.0V and TA = +25NC.
PAGE 5
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver Test Circuits and Waveforms (continued) S1 D 0 OR VCC OUT RL = 500Ω CL 50pF GENERATOR 50Ω VCC DE VCC/2 tDZH, tDZH(SHDN) 0 0.25V OUT VOH VOM = (0 + VOH)/2 0 tDHZ Figure 4. Driver Enable and Disable Times (tDHZ, tDZH, tDZH(SHDN)) VCC RL = 500Ω S1 0 OR VCC D OUT CL 50pF GENERATOR 50Ω VCC DE VCC/2 tDZL, tDZL(SHDN) 0 tDLZ VCC VOM = (VOL + VCC)/2 OUT VOL 0.25V Figure 5.
PAGE 6
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver Test Circuits and Waveforms (continued) RECEIVER OUTPUT B VID ATE R A +1V B -1V tRPLH VOH A RO tRPHL VCC/2 VOL THE RISE TIME AND FALL TIME OF INPUTS A AND B < 4ns Figure 6. Receiver Propagation Delay Test Circuit Figure 7. Receiver Propagation Delays S1 +1.5V S3 VCC 1kΩ -1.5V VID CL 15pF GENERATOR S2 50Ω S1 OPEN S2 CLOSED VS3 = +1.5V S1 CLOSED S2 OPEN VS3 = -1.
PAGE 7
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver Typical Operating Characteristics (VCC = +5.0V, TA = +25°C, unless otherwise noted.) 1.30 1.20 DE = VCC 1.10 DE = 0 1.00 0.80 40 30 20 MAX14780E toc03 50 40 30 20 10 0 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 1 2 4 3 0 5 0 1 3 2 4 5 OUTPUT LOW VOLTAGE (V) RECEIVER OUTPUT-HIGH VOLTAGE vs. TEMPERATURE RECEIVER OUTPUT-LOW VOLTAGE vs. TEMPERATURE DRIVER DIFFERENTIAL OUTPUT CURRENT vs.
PAGE 8
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver Typical Operating Characteristics (continued) (VCC = +5.0V, TA = +25°C, unless otherwise noted.) 7 6 5 4 3 2 1 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 tDPHL 500 tDPLH 450 400 350 300 MAX14780E toc12 550 180 RECEIVER PROPAGATION DELAY (ns) 8 600 MAX14780E toc11 SHUTDOWN CURRENT (µA) 9 DRIVER PROPAGATION DELAY (ns) MAX14780E toc10 10 RECEIVER PROPAGATION DELAY vs.
PAGE 9
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver Pin Configuration + RO 1 R RE 2 DE 3 DI 4 D 8 VCC 7 B 6 A 5 GND SO/PDIP Pin Description PIN NAME FUNCTION 1 RO Receiver Output. When RE is low and if (A - B) R -50mV, RO is high; if (A - B) P -200mV, RO is low. 2 RE 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.
PAGE 10
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver Detailed Description The MAX14780E high-speed transceiver for RS-485/ RS-422 communication contains one driver and one receiver. This device features fail-safe circuitry, which guarantees a logic-high receiver output when the receiver inputs are open or shorted, or when they are connected to a terminated transmission line with all drivers disabled (see the Fail-Safe section).
PAGE 11
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver CMOS input. Whenever VCC drops below 1V, the hotswap input is reset. For RE there is a complementary circuit employing two pMOS devices pulling RE to VCC. ±30kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly.
PAGE 12
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 150pF RD 330Ω I 100% 90% DISCHARGE RESISTANCE STORAGE CAPACITOR IPEAK RC 50MΩ TO 100MΩ DEVICE UNDER TEST 10% tr = 0.7ns TO 1ns t 30ns 60ns Figure 10c. IEC 61000-4-2 ESD Test Model Applications Information The standard RS-485 receiver input impedance is 12kΩ (1-unit load), and the standard driver can drive up to 32-unit loads.
PAGE 13
MAX14780E +5.0V, ±30kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceiver 120Ω 120Ω DE B B DI D D DI DE RO A B A B A A R R RO RE RE R R D D MAX14780E DI DE RO RE DI DE RO RE Figure 11. Typical Half-Duplex RS-485 Network Package Information Typical Applications The MAX14780E transceiver is designed for bidirectional data communications on multipoint bus transmission lines. Figure 11 shows a typical network applications circuit.
PAGE 14
MAX14780E +5.