News & Events
Intersil Adds New 3.3-V RS-485/422 Transceivers to Interface Family
-- New 3.3-V transceivers operate over a +/-10% voltage range to reduce supply cost
MILPITAS, CA, October 15, 2003 Intersil Corporation (NASDAQ: ISIL), a world leader in the design and manufacture of high performance analog solutions, today announced two new RS-485/422 serial data transceivers designed for 3.3-V applications. The ISL83483 and ISL83485 operate from a wide +/-10% voltage range of +3 to +3.6 V, which relaxes supply requirements and reduces costs. Many competing products require a more costly +/-5% supply tolerance. Applications for these data transceivers include, but are not limited to, factory automation, security networks and building environmental control.
Both the ISL83483 and ISL83485 are half-duplex transceivers whose receive (Rx) and transmit (Tx) functions are multiplexed, reducing pin count and package size with only 8-leads. Rx inputs feature a fail-safe-if-open design, which ensures a logic high Rx output if Rx inputs are floating. A "lock-out" feature keeps the Rx output disabled, when exiting shutdown, until the Rx has determined what state it should go to. This prevents the Rx output from accidentally generating an interrupt while the Rx wakes up. Although these are 3.3-V devices, their logic inputs can be driven with 5-V logic levels in mixed voltage systems.
Driver outputs are short circuit protected, even for voltages exceeding the power supply voltage. Additionally, on-chip thermal shutdown circuitry disables the Tx outputs to prevent damage if power dissipation becomes excessive. Each device supports a combination of up to 32 drivers and receivers on a single bus enabling bi-directional communications over a single twisted-pair cable. In addition, both devices have an automatic low-power shutdown feature in which the device draws only 15 nA (typical).
The ISL83483 is slew-rate limited for error free data transmission in applications where the data rate is less than 250 kbps, typically used for long runs. Slew-rate limiting reduces EMI and minimizes reflections from improperly terminated transmission lines, or unterminated stubs in multi-drop and multipoint applications.
The ISL83485 can operate up to 10 Mbps for high-speed applications. These transceivers are built using the Intersil BiCMOS process and meet both the RS-485 and RS-422 standards for balanced (differential) communication. Balanced data-transmission schemes offer robust noise immunity for data communications over long distances.
The typical use for RS-485 is a single PC connected to several addressable devices that share the same cable. RS-422 is similar to RS-485 except that only one driver and up to ten receivers are allowed on the bus. The single driver limitation requires two twisted pairs for bi-directional communications.
ISL83483 and ISL83485 Technical Details
- Pin-for-pin replacements for competing products of similar nomenclature
- +3.3 V supply, +/-10% voltage tolerance, +3.0 to +3.6 V range
- Half -duplex bi-directional operation, differential signaling
- Low power shutdown mode
- Logic inputs accept 5-V logic levels
- Rx lock-out prevents errors during wakeup
- RS-485 and RS-422 compliant
- ISL83483 slew-rate limited, less than 250 kbps data rate, low EMI
- ISL83485 10 Mbps data rate
- -7 to +12 V common-mode input voltage range for reliable operation over long, noisy runs
- Single-unit RS-485 loading allows 32 units on the bus
- On-chip thermal shutdown
- Driver outputs short-circuit protected
- 8-lead PDIP and SOIC packages
The ISL83483 and ISL83485 are available now. Suggested resale pricing for 100- to 999-unit quantities is $1.21 each for the ISL83483IB (SOIC package) and ISL83483IP (PDIP package) and $1.05 each for the ISL83485IB (SOIC package) and ISL83485IP (PDIP package). Both are available on tape and reel. Visit this Intersil Web site for cross-reference and other information: http://www.intersil.com/design/interface/rs-485.asp About Intersil
Intersil Corporation is a leader in the design and manufacture of high performance analog semiconductors. The company’s products address three of the industry’s fastest growing markets - flat panel displays, optical storage (CD and DVD recordable) and power management. Intersil products include power management devices for battery management, hot-swap and hot-plug controllers, linear regulators, supervisory ICs, switching DC-DC regulators and power MOSFET drivers; optical storage laser diode drivers; DSL line drivers; video and high performance operational amplifiers; data converters; interface ICs; analog switches and multiplexers; crosspoint switches; voice-over-IP devices; and ICs for military, space and rad-hard applications. For more information about Intersil or to find out how to become a member of our winning team, visit the company’s web site and career page at: www.intersil.com
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