IL4822 / IL4622 / IL4685

10

NVE Corporation

11409 Valley View Road, Eden Prairie, MN 55344

(952) 829-9217

www.nve.com

YouTube.com/NveCorporation

iso-apps@ www.nve.com

Optional External Regulation

An external regulator can be connected to the VF pin and used in addition to the parts’ internal low drop-out regulator for voltages

up to approximately 7.5 volts. The maximum output current decreases at higher regulator output voltages, but the output power

capacity remains approximately 250 milliwatts.

Transceiver Operation

Receiver Features

The receiver output “R” has tri-state capability via the active low RE input.

Driver Features

The driver features low propagation delay skew to maximize bit width and minimize EMI. Drivers have tri-state capability via the

active-high DE input.

True 3.3-volt Bus Operation

IL46xx parts are guaranteed to provide the minimum RS-485 / RS-422 differential voltages with a 3.0-volt bus supply, providing true 3.3-volt

bus operation with ample design margins.

Deterministic Power Up and Brownout Detection

IL46xx parts have circuitry to disable the transceiver bus until the driver-side voltage (VDD2B, normally provided by the DC-to-

DC convertor) reaches approximately 2.5 volts on power-up. The transceiver is disabled when the voltage drops below

approximately 2.3 volts on power-down. This brownout circuitry ensures the transceiver does not “crash” the bus on power up,

power down, or brownout, and eliminates the need for external power supply monitors. In addition, a patented refresh circuit

maintains the correct transceiver output state with respect to data input (DC correctness). The refresh circuit ensures the bus

outputs will follow the Function Table shown on Page 1 after power up.

Hot Plug Operation

Deterministic power-up allows IL46xx nodes to “hot plug” into the bus since the bus driver will be in a high-impedance state until

the DC-to-DC convertor output is enough for the bus driver to operate.

Unpowered Nodes

The bus driver reverts to high impedance when VDD2 is not present so that unpowered nodes do not disturb bus operation.

Full Fail-Safe

The receiver is fully fail-safe, meaning it guarantees a logic high state on “R” if the “A” and “B” bus inputs are unconnected,

shorted together, or connected to a terminated bus with all the transmitters disabled (terminated/undriven).

Rigorous PROFIBUS Compatibility

Unlike most other transceivers, IL4822 transceivers meet stringent PROFIBUS standards for maximum differential output voltage

as well as other PROFIBUS requirements.

Thermal Shutdown

Internal DC-to-DC convertor thermal management circuitry gradually limits the output voltage and power output to approximately

250 mW as the junction temperature increases to avoid thermal overload (see Figure 10).

In addition, the bus driver is disabled when the driver die temperature exceeds approximately 150 °C, and re-enabled when the die

temperature drops below approximately 135 °C. The receiver and DC-to-DC convertor sections continue to operate during thermal

shutdown.

Internal Connections

Ground Connections

There are two pins for each ground connection: pin 2 is internally connected to pin 8 and pin 15 is internally connected to pin 9.

All four ground pins should be soldered to circuit board traces to maximize power dissipation.