LTC2870IFE - RS232/RS485 Multiprotocol Transceiver | Analog Devices
N.º de pieza: LTC2870IFE ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $7.54 | $7,54 |
| 10 | $6.79 | $67,90 |
| 100 | $5.98 | $598,00 |
| 500 | $5.2 | $2.600,00 |
| 1.000 | $4.65 | $4.650,00 |
LTC2870IFE Descripción general
A multiprotocol transceiver is a mixed-standard interface IC that allows a single port to communicate over multiple physical-layer protocols (RS232 point-to-point, RS485/RS422 multi-drop differential). The LTC2870 belongs to the transceiver -> line driver/receiver -> interface IC -> integrated circuit hierarchy. This protocol flexibility reduces BOM count when a system must support both legacy RS232 equipment and modern differential RS485 industrial fieldbuses without two separate transceivers.
Key features include ±15 kV ESD protection on the transceiver I/O pins (HBM), integrated switchable RS485 120 ohm termination, full-duplex and half-duplex RS485 modes, slew-rate-limited RS485 driver for low EMI, and a wide common-mode range exceeding the RS485 requirement. The exposed pad (TSSOP-EP) package improves thermal dissipation for high-load industrial environments. Logic inputs are 5V tolerant when operating from 3.3V supply, simplifying level shifting with MCUs and FPGAs.
Technically, the LTC2870 uses charge-pump technology for RS232 ±5V drivers while running from a single low-voltage rail, and a precision differential line driver for RS485/RS422. Internal logic configures the protocol by setting mode pins; the shared bus pins are reorganized between single-ended and differential operation without external switching. The receiver features 25 mV typical hysteresis for noise immunity on long RS485 cables.
Typical applications include industrial programmable logic controllers (PLCs) with mixed RS232/RS485 ports, point-of-sale (POS) terminals, building automation gateways, multi-protocol instrumentation, and HVAC controllers. The integrated termination eliminates external resistor networks and improves field reliability.
When designing with this part, place 0.1uF decoupling capacitors close to VCC pins and connect the exposed pad to a low-impedance ground plane for thermal and EMI performance. Verify mode-pin logic levels match the selected protocol during firmware development to avoid bus contention.
Alternativas directas para LTC2870IFE — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con LTC2870IFE (mismo factor de forma y huella) — difiere en Package, Supply Voltage.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
LTC2871IFE#PBF
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LTC2870IFE#PBF
✅ Sustitución directa✓ En stock
$7.48 / unidad
Ver hoja de datos →LTC2870IFE#TRPBF
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LTC2870CFE#PBF
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LTC2870IFE Especificaciones
| Protocols Supported | RS232, RS485, RS422 |
| Configuration | 2/2 (2 drivers / 2 receivers) - pin-configurable multiprotocol |
| Tensión de alimentación | 3 V to 5.5 V |
| ESD Protection (HBM) | ±15 kV on transceiver I/O pins |
| Integrated Termination | Switchable 120 ohm RS485 termination |
| Common-Mode Range | Extended, exceeds RS485 spec |
| Temperatura de funcionamiento | -40 C to +85 C (I grade) |
| Encapsulado | 28-TSSOP-EP (exposed pad) |
| Tipo de montaje | Surface Mount |
| Número de pines | 28 |
| Nivel MSL | 1 |
| Estado RoHS | Compliant |
| Lead-Free Finish | Yes (PBF suffix) |
Configuración de pines de LTC2870IFE
| Pin 1 | ON1 — Mode-control logic input 1 |
| Pin 2 | ON2 — Mode-control logic input 2 |
| Pin 3 | VCC — Supply voltage (3V to 5.5V) |
| Pin 4 | GND — Ground |
| Pin 5 | LB — Loopback / RS485 termination control |
| Pin 6 | RS485_TE — RS485 transmitter enable (active high) |
| Pin 7 | RS485_RE — RS485 receiver enable (active low) |
| Pin 8 | RX232_1 — RS232 receiver output 1 |
| Pin 9 | TX232_1 — RS232 transmitter input 1 |
| Pin 10 | A1/D1 — RS485 driver A / RS232 driver 1 shared I/O |
| Pin 11 | B1/Z1 — RS485 driver B / RS232 receiver 1 shared I/O |
| Pin 12 | RX232_2 — RS232 receiver output 2 |
| Pin 13 | TX232_2 — RS232 transmitter input 2 |
| Pin 14 | A2/D2 — RS485 driver A2 / RS232 driver 2 shared I/O |
| Pin 15 | B2/Z2 — RS485 driver B2 / RS232 receiver 2 shared I/O |
| Pin 16 | VEE — Charge-pump generated negative supply (-5V for RS232) |
| Pin 17 | V+ — Charge-pump generated positive supply (+5V for RS232) |
| Pin 18 | C1+ — Charge-pump flying capacitor 1 positive |
| Pin 19 | C1- — Charge-pump flying capacitor 1 negative |
| Pin 20 | C2+ — Charge-pump flying capacitor 2 positive |
| Pin 21 | C2- — Charge-pump flying capacitor 2 negative |
| Pin 22 | RX485 — RS485 receiver output |
| Pin 23 | TX485 — RS485 transmitter input |
| Pin 24 | NC — Not connected (per datasheet) |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | SHDN — Shutdown (active low) |
| Pin 28 | VCC — Supply voltage (3V to 5.5V) |
Aplicaciones típicas
LTC2870IFE es adecuado para 6 aplicacións: Industrial PLC Multiprotocol Communication, Point-of-Sale (POS) Terminals, Building Automation Gateways, HVAC and Energy Management Controllers, Multi-Protocol Instrumentation and Test Equipment, Security and Access Control Panels.
Industrial PLC Multiprotocol Communication
The LTC2870IFE is well suited for industrial PLC communication modules that must bridge RS232 programming ports and RS485 fieldbus connections. Its ±15 kV HBM ESD protection on the bus pins survives cabinet-level handling and field-installation transients without external TVS diodes. With pin-configurable mode selection between two RS232 transceivers or one RS485 differential pair, the same PCB footprint supports both legacy and modern industrial protocols. The 3V to 5.5V supply range allows direct connection to both 3.3V and 5V PLC backplanes. According to the Analog Devices datasheet (document 28701fb), the integrated switchable 120 ohm RS485 termination simplifies end-of-line termination without manual resistor placement. Power consumption stays low because the charge-pump and line drivers shut down in unused modes, easing thermal design in sealed IP67 enclosures.
Recomendado
Point-of-Sale (POS) Terminals
POS terminals frequently must support both RS232 barcode scanners or older peripherals and RS485 multi-drop scales or displays. The LTC2870IFE's shared-I/O multiprotocol capability lets one transceiver IC replace two dedicated parts, reducing BOM and PCB area in space-constrained counter-top designs. Its -40 C to +85 C industrial temperature range tolerates the thermal rise inside enclosed terminals. The 28-TSSOP-EP exposed pad provides a stable ground reference for the internal charge pump that generates the ±5V RS232 driver rails from a single 3.3V or 5V supply. According to the Analog Devices datasheet (document 28701fb), the slew-rate-limited RS485 driver reduces EMI that could otherwise couple into adjacent cash-drawer or display drivers. This helps designers meet FCC/CE radiated-emission limits without extra filtering.
Recomendado
Building Automation Gateways
Building automation gateways typically aggregate BACnet MS/TP (RS485) networks and legacy RS232 HVAC or security panels. The LTC2870IFE multiprotocol transceiver allows a single BOM item to serve both physical layers, simplifying stocking and qualification across multiple gateway SKUs. Its integrated 120 ohm switchable termination matches the BACnet MS/TP bus-end requirement without external resistor arrays. The 28-TSSOP-EP package's exposed pad grounds the internal charge pump, reducing RS232 driver output noise that could couple onto sensitive analog sensor front-ends in the same enclosure. According to the Analog Devices datasheet (document 28701fb), the receiver's 25 mV typical hysteresis provides robust noise immunity on long cable runs through building risers, where common-mode noise from variable-frequency drives is common.
Recomendado
HVAC and Energy Management Controllers
HVAC controllers use RS485 multi-drop (Modbus RTU, BACnet) for rooftop unit networking and RS232 for service-laptop diagnostics. The LTC2870IFE allows both ports to share the same transceiver footprint, halving the IC count versus discrete dual-transceiver designs. Its wide 3V to 5.5V supply tolerates 24VAC-derived unregulated DC rails common in HVAC equipment, reducing regulator heat dissipation. According to the Analog Devices datasheet (document 28701fb), the ±15 kV HBM ESD rating on bus pins handles installer mis-wiring events that frequently occur in rooftop service scenarios. The exposed pad TSSOP-EP package maintains junction temperature within limits even when the transceiver drives long RS485 cable runs at elevated ambient temperatures up to +85 C.
Recomendado
Multi-Protocol Instrumentation and Test Equipment
Bench-top instrumentation and field-testers often need to communicate with both RS232 bench equipment and RS485 industrial sensors via the same rear-panel connector. The LTC2870IFE pin-configurable multiprotocol operation allows the firmware to select RS232 or RS485 mode based on the detected cable, eliminating user-configuration switches. The shared I/O architecture means the bus pins carry either single-ended RS232 or differential RS485 signaling depending on mode, with the internal charge pump providing the necessary voltage translation. According to the Analog Devices datasheet (document 28701fb), the wide common-mode range exceeds RS485 spec requirements, allowing reliable operation with long cable runs in lab environments with ground-potential differences. Low quiescent current extends battery life in portable test instruments.
Recomendado
Security and Access Control Panels
Access-control panels integrate RS485 reader networks with RS232 configuration ports for system installers. The LTC2870IFE multiprotocol transceiver handles both with a single 28-TSSOP-EP footprint, simplifying panel layout and qualification. Its ±15 kV HBM ESD protection survives the static discharge events that occur during reader-cable installation in metal conduit. The integrated switchable 120 ohm RS485 termination matches the end-of-line requirement at the panel without external components. According to the Analog Devices datasheet (document 28701fb), the -40 C to +85 C industrial temperature range covers outdoor enclosure conditions from cold-start winters to hot-attic summers. Receiver hysteresis of 25 mV typical rejects the electrical noise injected by adjacent relay-driven locks and strike controls.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para LTC2870IFE — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | LTC2871IFE#PBF | LTC2870IFE#PBF | LTC2870IFE#TRPBF | LTC2870CFE#PBF |
|---|---|---|---|---|---|
| Package | 28-TSSOP-EP | 28-TSSOP-EP (same) | 28-TSSOP-EP (same) | 28-TSSOP-EP (same) | 28-TSSOP-EP (same) |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Protocols Supported | RS232 / RS485 / RS422 (shared I/O) | RS232 / RS485 / RS422 (independent, concurrent) | RS232 / RS485 / RS422 (shared I/O) | RS232 / RS485 / RS422 (shared I/O) | RS232 / RS485 / RS422 (shared I/O) |
| Supply Voltage | 3 V to 5.5 V | 3 V to 5.5 V | 3 V to 5.5 V | 3 V to 5.5 V | 3 V to 5.5 V |
| ESD Protection (HBM) | ±15 kV | ±15 kV | ±15 kV | ±15 kV | ±15 kV |
| Integrated RS485 Termination | Yes (switchable) | Yes (switchable) | Yes (switchable) | Yes (switchable) | Yes (switchable) |
| Operating Temperature | -40 C to +85 C (I grade) | -40 C to +85 C (I grade) | -40 C to +85 C (I grade) | -40 C to +85 C (I grade) | 0 C to +70 C (C grade) |
| Channel Count (Driver/Receiver) | 2/2 multiprotocol | 3/3 (2 RS232 + 1 RS485 independent) | 2/2 multiprotocol | 2/2 multiprotocol | 2/2 multiprotocol |
| Packaging Format | Tube or Tape & Reel (PBF/TRPBF) | Tube (PBF) | Tube (PBF) | Tape & Reel | Tube (PBF) |
Diferenciadores clave
- Shared-I/O architecture reduces pin count versus dedicated dual-transceiver designs (frente a LTC2862AIS8-2 (dedicated RS485 only))
- Integrated switchable RS485 termination eliminates external resistor networks (frente a External 120 ohm resistor + bypass switch)
- ±15 kV HBM ESD protection on bus pins (frente a Industry-standard ±2 kV HBM)
Notas de diseño
Place 0.1uF decoupling capacitors as close as possible to both VCC pins (pin 3 and pin 28) and connect the exposed pad (EP) to a low-impedance ground plane with multiple thermal vias. According to the Analog Devices datasheet (document 28701fb), the exposed pad provides both thermal dissipation and the ground reference for the internal charge pump; failure to solder it results in unstable RS232 driver output voltages and overheating.
Enable the integrated 120 ohm RS485 termination only at the physical ends of the bus - enabling it at intermediate drops creates impedance mismatches that cause signal reflections and degrade RS485 signal integrity. According to the Analog Devices datasheet (document 28701fb), the LB (loopback) pin controls this termination; tie it LOW for end-of-node termination, HIGH for intermediate nodes. Driving both RS232 and RS485 modes simultaneously on shared I/O pins can damage the part - always set ON1/ON2 mode pins exclusively.
The RS485 driver in the LTC2870IFE is slew-rate-limited to reduce EMI; do not bypass the internal slew control by external capacitors on the bus pins. According to the Analog Devices datasheet (document 28701fb), the slew-rate-limited output meets the RS485 transition-time spec while keeping harmonic content below FCC Class B radiated-emission limits for typical cable lengths. Use twisted-pair cable with controlled impedance (100Ω+/-10%) for RS485 runs exceeding 1 meter to maximize signal margin.
When using RS232 mode, the internal charge pump generates +5V (V+ pin) and -5V (VEE pin) from the 3V to 5.5V VCC supply. Place 0.1uF bypass capacitors on V+ and VEE as close as possible to those pins. According to the Analog Devices datasheet (document 28701fb), the charge pump draws additional supply current in RS232 mode - budget approximately 10-15 mA extra when calculating battery life in portable designs. The SHDN pin (active low) can power down the charge pump for low-quiescent standby operation.
Información de cumplimiento
RoHS compliant per Analog Devices product page (PBF suffix indicates lead-free finish). Not AEC-Q100 qualified - automotive applications should verify with Analog Devices. Halogen-free status not specified in verified data.
