Descripción general

The MAX14783E is a half-duplex RS-485 transceiver that operates at either 3.3V or 5V rails with high ±35kV ESD performance and up to 42Mbps data rate. The device is optimized for high speeds over extended cable runs while maximizing tolerance to noise.

The MAX14783E is available in 8-pin µMAX, 8-pin SO, and 8-pin TDFN-EP packages. The device in the TDFN-EP package operates over the -40°C to +125°C temperature range. The MAX14783E in the μMAX and SO packages operates over the -40°C to +85°C and -40°C to +125°C temperature ranges.

 

Aplicaciones

Motion Controllers

Field Bus Networks

Encoder Interfaces

Backplane Busses

 

Ventajas y características

Integrated Protection Increases Robustness

High ESD Protection

±35kV HBM ESD per JEDEC JS-001-2012

±20kV Air Gap per IEC 61000-4-2

±12kV Contact ESD per IEC 61000-4-2

±4kV EFT per IEC 61000-4-4

Short-Circuit Protected Outputs

True Fail-Safe Receiver Prevents False Transition on Receiver Input Short or Open Events

Hot-Swap Capability Eliminates False Transitions

During Power-Up or Hot Insertion

3V to 5.5V Supply Voltage Range

High-Speed Data Rates up to 42Mbps

-40°C to +125°C Operating Temperature

Allows Up to 32 Transceivers on the Bus

Low 10µA (max) Shutdown Current for Lower Power Consumption

 

More Information

Descripción detallada

The MAX14783E is a 3.3V/5V ESD-protected RS-485/RS-422 transceiver intended for high-speed, half-duplex communications. Integrated hot-swap functionality eliminates false transitions on the bus during power-up or hot insertion.

The device features fail-safe receiver inputs guaranteeing a logic-high receiver output when inputs are shorted or open. The IC has a 1-unit load receiver input impedance, allowing up to 32 transceivers on the bus.

True Fail Safe

The MAX14783E 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. If the differential receiver input voltage (A–B) is greater than or equal to -10mV, RO is logic-high.

Driver Single-Ended Operation

The A and B outputs can either be used in the standard differential operating mode, or can be used as singleended outputs. Since the A and B driver outputs swing rail-to-rail, they can individually be used as standard TTL logic outputs.

Hot-Swap Inputs

When circuit boards are inserted in a hot or powered backplane, disturbances on the enable inputs and differential receiver inputs can lead to data errors. Upon initial circuit board insertion,the processor undergoes its power-up sequence. During this period, the processor output drivers are high impedance and are unable to drive the DE and RE inputs of the MAX14783E to a defined logic level. Leakage currents up to 10µA from the high impedance outputs of a controller could cause DE and RE to drift to an incorrect logic state. Additionally,parasitic circuit board capacitance could cause coupling of VCC or GND to DE and RE. These factors could improperly enable the driver or receiver. The MAX14783E features integrated hot-swap inputs that help to avoid these potential problems.

When VCC rises, an internal pulldown circuit holds DE low and RE high. After the initial power-up sequence, the pulldown circuit becomes transparent, resetting the hot swap-tolerable inputs.

±35kV ESD Protection

ESD protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs of the MAX14783E have extra protection against static electricity. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, the MAX14783E keeps working without latch-up or damage.

Protección de la salida del conductor

Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus connection. The first, a current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range. The second, a thermal-shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature exceeds +160°C (typ).