SP485E - Enhanced Low Power Half-Duplex RS-485/RS-422 Transceiver | MaxLinear
MPN: SP485E ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.62 | $16.20 |
| 100 | $1.28 | $128.00 |
| 500 | $1.05 | $525.00 |
| 1,000 | $0.92 | $920.00 |
SP485E Overview
An RS-485/RS-422 transceiver is a physical-layer interface IC that converts a single-ended UART signal into a differential signal suitable for transmission over twisted-pair cable. RS-485 is the most widely used industrial multipoint bus standard, supporting up to 32 unit loads (256 with repeaters) over cable lengths up to 1200 m. Within the broader hierarchy, the SP485E belongs to: transceiver -> line driver/receiver -> interface IC -> integrated circuit -> semiconductor. Half-duplex operation means a single differential pair carries data in both directions, but only one direction at a time, controlled by a driver-enable pin.
Key features of the SP485E include ±200 mV receiver input sensitivity, 12 kΩ minimum input impedance (typically 15 kΩ), a wide common-mode range of −7 V to +12 V, and tri-state driver and receiver enable pins. The receiver failsafe design guarantees a known output state when the bus is idle, open, or shorted. Supply current is typically below 1 mA in active mode, supporting battery-powered and energy-conscious designs.
Architecturally, the BiCMOS process combines bipolar drive strength with CMOS logic density, achieving older bipolar designs' robustness at a fraction of the quiescent power. The wide common-mode range accommodates large ground potential differences between networked nodes, which is essential in industrial installations where motor drives, PLCs, and sensors share long cable runs.
Typical applications include factory-floor RS-485 networks, building-automation daisy chains, point-of-sale terminals, industrial sensor backbones, and multidrop utility metering. The enhanced ESD rating simplifies board design by reducing or eliminating external TVS protection.
A key design consideration is termination: a 120 Ω resistor across the differential pair at each cable end minimizes reflections for high-speed or long-cable links. Biasing resistors may also be required on an idle bus to maintain the failsafe state when no driver is enabled. The 8-pin SOIC footprint is pin-to-pin compatible with the industry-standard MAX485 and ST485, enabling drop-in replacement.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, giving engineers a single reference for sourcing and second-sourcing the SP485E.
Drop-in alternatives for SP485E — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SP485EEN-L
✅ Drop-In📋 Reference alternative (not in catalog)
SP485EEP-L
✅ Drop-In📋 Reference alternative (not in catalog)
SP481EEN-L
✅ Drop-In📋 Reference alternative (not in catalog)
MAX485ESA+T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX485CPA+
✅ Drop-In✓ In Stock
$7.3596 / Unit
View Datasheet →ST485ECDR
✅ Drop-In📋 Reference alternative (not in catalog)
SN75176BDR
✅ Drop-In✓ In Stock
$0.1055 / Unit
View Datasheet →SP485E Specifications
| Function | Transceiver |
| Protocol | RS-485, RS-422 |
| Number of Drivers/Receivers | 1/1 |
| Duplex | Half-duplex |
| Data Rate | 2.5 Mbps (max, SP485E non-slew-limited) |
| Supply Voltage (VCC) | 4.75 V to 5.25 V |
| Receiver Input Sensitivity | ±200 mV |
| Receiver Input Impedance | 12 kΩ minimum, 15 kΩ typical |
| Common-Mode Range | −7 V to +12 V |
| ESD Protection (HBM) | ±15 kV |
| ESD Protection (IEC 61000-4-2 Air Discharge) | ±15 kV |
| Package | 8-pin NSOIC or PDIP |
| Mounting Type | Surface Mount (NSOIC) or Through-Hole (PDIP) |
| Process Technology | BiCMOS |
| Failsafe Receiver | Yes (open, shorted, idle bus) |
| Tri-State Enable Pins | Yes (DE, RE) |
| RoHS Status | Compliant |
SP485E Pin Configuration
| Pin 1 | RO — Receiver Output (logic-level, referenced to VCC/GND) |
| Pin 2 | RE — Receiver Enable (active-low; tie low or to DE for normal operation) |
| Pin 3 | DE — Driver Enable (active-high; tie high or to RE for normal operation) |
| Pin 4 | DI — Driver Input (TTL/CMOS logic-level) |
| Pin 5 | GND — Ground reference |
| Pin 6 | A — Non-inverting differential bus input/output |
| Pin 7 | B — Inverting differential bus input/output |
| Pin 8 | VCC — 5V supply input (4.75 V to 5.25 V) |
Typical Applications
SP485E is suitable for 6 applications: Industrial RS-485 Multidrop Networks, Building Automation and HVAC Networks, Point-of-Sale and Retail Peripherals, Utility Metering and Smart-Grid Backhaul, Solar Inverter and Energy-Storage Communications, Security and Access-Control Panels.
Industrial RS-485 Multidrop Networks
The SP485E is a natural fit for industrial multidrop RS-485 networks where multiple nodes communicate over a single twisted pair. Its half-duplex topology with one driver and one receiver, combined with the wide −7 V to +12 V common-mode range, accommodates large ground potential differences between distributed motor drives, PLCs, and sensors across factory floors. The ±15 kV ESD rating significantly improves field reliability versus MAX485-class parts, reducing warranty returns from cable-handling events. Cable lengths up to 1200 m at speeds up to 2.5 Mbps are achievable with proper 120 Ω termination at both cable ends.
Recommended
Building Automation and HVAC Networks
In building-automation backbones for HVAC controllers, lighting control panels, and access systems, the SP485E provides the reliable physical layer for daisy-chained RS-485 buses. Its 5 V supply and BiCMOS low-power operation keep quiescent draw under 1 mA, suitable for always-on wall controllers and thermostats. The ±200 mV receiver sensitivity and built-in failsafe guarantee defined bus states when segments are idle or being serviced, preventing spurious commands in lighting and access-control systems. With proper shielding and 120 Ω termination, a single SP485E bus can span multi-floor commercial installations reliably.
Recommended
Point-of-Sale and Retail Peripherals
Point-of-sale terminals, barcode scanners, and electronic cash drawers often use RS-485 daisy chains to connect multiple peripherals to a central terminal with a single cable run. The SP485E's 2.5 Mbps capability supports fast polling of receipt printers, customer displays, and scanners without bottlenecking the bus. Its 8-pin SOIC footprint keeps the PCB compact inside space-constrained terminal enclosures, and the enhanced ±15 kV ESD protection defends against static discharge from frequent cable insertion by retail staff. The receiver failsafe feature prevents phantom-key scans when segments are temporarily disconnected for service.
Recommended
Utility Metering and Smart-Grid Backhaul
Smart electricity, water, and gas meters frequently use RS-485 multidrop links to aggregate consumption data from multiple units in a residential or commercial cluster. The SP485E's wide common-mode range (−7 V to +12 V) tolerates the ground offsets that occur in large multi-unit installations sharing a single backbone cable. Its low quiescent current minimizes the impact on battery-backed metering nodes, while the enhanced ESD rating handles the transients induced by long outdoor cable runs near switching loads. The 1200 m cable reach at lower data rates easily covers typical multi-unit residential or light-industrial metering clusters.
Recommended
Solar Inverter and Energy-Storage Communications
Solar inverters, battery management systems, and DC string monitors increasingly use RS-485 to coordinate module-level data across PV installations. The SP485E provides a robust 5 V physical layer that survives the high-voltage transients common in solar installations when paired with external isolation. Its ±15 kV ESD rating reduces the need for separate TVS protection, simplifying the BOM for cost-sensitive residential PV string combiners. The 2.5 Mbps data rate supports frequent telemetry updates from many parallel inverters without bus saturation, and the half-duplex architecture minimizes wiring complexity in field installations.
Recommended
Security and Access-Control Panels
Access-control panels, card readers, and alarm sensors are frequently daisy-chained on RS-485 buses running through commercial buildings. The SP485E's failsafe receiver prevents false door-unlock commands when a reader is disconnected or the bus is shorted, a critical safety property for security systems. Its enhanced ±15 kV ESD rating protects against static discharge from installer cabling work, reducing field-failure rates. The 8-pin SOIC footprint allows compact panel-internal PCB layouts, while the BiCMOS low quiescent current keeps standby power consumption minimal across many daisy-chained security nodes.
Recommended
Recommended Products Summary
Engineering reference data for SP485E — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SP485EEN-L | SP481EEN-L | MAX485ESA+T | ST485ECDR | SN75176BDR |
|---|---|---|---|---|---|---|
| Brand | MaxLinear | MaxLinear | MaxLinear | Analog Devices | STMicroelectronics | Texas Instruments |
| Package | NSOIC-8 or PDIP-8 | NSOIC-8 - same | NSOIC-8 - same | NSOIC-8 - same | NSOIC-8 - same | NSOIC-8 - same |
| Protocol | RS-485, RS-422 | RS-485, RS-422 | RS-485, RS-422 | RS-485, RS-422 | RS-485, RS-422 | RS-485, RS-422 |
| Duplex | Half-duplex | Half-duplex | Half-duplex | Half-duplex | Half-duplex | Half-duplex |
| Data Rate | 2.5 Mbps | 2.5 Mbps | 250 kbps (slew-rate-limited) | 2.5 Mbps | 2.5 Mbps | 2.5 Mbps (typical) |
| Supply Voltage | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V |
| ESD Protection (HBM) | ±15 kV | ±15 kV | ±15 kV | ±2 kV (typical) | ±2 kV (typical) | ±2 kV (typical) |
| Common-Mode Range | −7 V to +12 V | −7 V to +12 V | −7 V to +12 V | −7 V to +12 V | −7 V to +12 V | −7 V to +12 V |
Key Differentiators
- ±15 kV enhanced ESD protection on bus pins (vs MAX485ESA+T)
- Industry-leading 2.5 Mbps data rate (vs SP481EEN-L)
- Wide common-mode range for industrial ground offsets (vs SN75176BDR)
Design Notes
Place the SP485E close to the bus terminals and route the differential A/B pair as a matched-impedance pair with controlled 100 Ω differential impedance. Keep the A/B traces short, parallel, and routed over a continuous ground plane to minimize reflections and EMI. The DE/RE control lines should be routed away from the bus traces to avoid capacitive coupling, and a 100 nF decoupling capacitor should be placed within 5 mm of the VCC pin.
Do not leave DE and RE floating; the SP485E draws higher supply current if both are in undefined states. Tie RE low and drive DE high only when the UART is transmitting. When designing failsafe biasing for an idle bus, add a pull-up on A and a pull-down on B with values in the 100 kΩ to 1 MΩ range to keep the differential voltage above the +200 mV threshold and prevent phantom receiver outputs. Avoid mixing the SP485E with 3.3V transceivers on the same bus without level shifters, since 5V common-mode transients will damage 3.3V parts.
Use a 120 Ω termination resistor at each end of the bus cable only, never at intermediate nodes, to prevent excessive loading. If stub lengths exceed approximately 1/10 of the driver's rise time (about 4 cm at 2.5 Mbps), the SP485E's 2.5 Mbps non-slew-limited drivers may cause reflections; in such cases, switch to the slew-rate-limited SP485 or SP481E siblings. For long cables or noisy industrial environments, add a common-mode choke and TVS protection array externally even though the SP485E has ±15 kV ESD protection, to defend against surge events beyond the ESD window.
Compliance Information
RoHS compliant per MaxLinear product page. Not AEC-Q100 qualified - the SP485E is intended for industrial/commercial RS-485 applications, not automotive. Meets RS-485 and RS-422 standards per TIA/EIA-485 and TIA/EIA-422, and is tested to IEC 61000-4-2 Air Discharge at ±15 kV.
