LTC2870IFE#PBF - RS232/RS485 Multiprotocol Transceiver | Analog Devices
부품 번호: LTC2870IFE#PBF ✓ 활성| 수량 | 단가 | 합계 |
|---|---|---|
| 1 | $11.42 | $11.42 |
| 10 | $10.51 | $105.10 |
| 100 | $9.42 | $942.00 |
| 500 | $8.36 | $4,180.00 |
| 1,000 | $7.48 | $7,480.00 |
LTC2870IFE#PBF 개요
An RS232/RS485 multiprotocol transceiver is an interface IC that bridges a UART, microcontroller, or processor to a physical serial bus. The RS232 standard uses single-ended signaling (logic-high and logic-low on separate lines with ±5V to ±15V swings) and is common in point-to-point links to legacy PCs and industrial controllers. The RS485 standard uses differential signaling (A-B differential voltage) and enables multipoint half-duplex or full-duplex networks up to 1200 m with up to 32 unit loads. Multiprotocol transceivers combine both physical layers on shared pins so a single PCB footprint can serve multiple end-equipment variants, reducing BOM and qualification cost.
Key features of the LTC2870 include shared I/O lines between RS232 and RS485 modes, automatic or logic-controlled 120 ohm RS485 termination, ±25 kV ESD HBM on the bus I/O pins, hot-swap glitch protection, and a low-current shutdown mode. The integrated loopback mode allows self-test of the RS232 path without external cabling. The single 3V to 5.5V supply eliminates the negative charge pump traditionally required for RS232, simplifying power tree design.
Typical applications include industrial multipoint fieldbus nodes, point-of-sale terminals, RS232-to-RS485 protocol converters, and any system that must communicate to both legacy RS232 equipment and modern RS485 networks. The TSSOP-EP package provides low thermal resistance for reliable operation at the extended industrial temperature range. When designing with the LTC2870, the shared I/O pins require careful PCB routing to avoid coupling between RS232 single-ended and RS485 differential traces; the exposed pad must be soldered to a thermal copper pour for specified thermal performance.
드롭인 대체품: LTC2870IFE#PBF — 동일 패키지, 핀 호환. PCB 재작업이 필요한 다른 패키지 부품은 제외됩니다.
이 시리즈의 변형
다음과 드롭인 호환되는 동일 시리즈 모델: LTC2870IFE#PBF (동일 폼 팩터 및 풋프린트) — 차이점: Package, Supply Voltage.
빠른 비교 도구 — 나란히 비교할 대체 부품을 선택하십시오:
LTC2870CFE#PBF
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
LTC2870IFE
✅ 드롭인✓ 재고 있음
$4.65 / 개
데이터시트 보기 →LTC2871IFE#PBF
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
LTC2871CFE#PBF
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
LTC2870IFE#PBF 사양
| Protocol | RS232, RS485, RS422 (pin-configurable multiprotocol) |
| 공급 전압 | 3 V to 5.5 V (single supply) |
| Number of Drivers/Receivers | 2/2 (Full Duplex) |
| Data Rate (RS485) | 20 Mbps |
| Data Rate (RS232) | 500 kbps |
| ESD Protection (HBM, Bus Pins) | ±25 kV |
| Integrated RS485 Termination | 120 ohm, pin-selectable |
| 동작 온도 범위 | -40 C to +85 C (Industrial) |
| 패키지 | 28-pin TSSOP-EP (FE) |
| 실장 유형 | Surface Mount |
| Duplex Mode | Full Duplex |
| RoHS 상태 | Compliant |
| MSL 레벨 | 1 |
LTC2870IFE#PBF 핀 구성
| 핀 1 | RX485 — RS485 receiver output (logic-level) |
| 핀 2 | RX232A — RS232 receiver output, channel A |
| 핀 3 | RX232B — RS232 receiver output, channel B |
| 핀 4 | GND — Ground |
| 핀 5 | VCC — Supply input, 3V to 5.5V |
| 핀 6 | MODE — Mode-select logic (RS232 / RS485) |
| 핀 7 | TE485 — RS485 driver enable |
| 핀 8 | TE232A — RS232 driver enable, channel A |
| 핀 9 | TE232B — RS232 driver enable, channel B |
| 핀 10 | RE485 — RS485 receiver enable (active low) |
| 핀 11 | ONOFF — [DATA_NEEDED: pin name from datasheet] |
| 핀 12 | LB — Loopback test mode (RS232) |
| 핀 13 | D485 — RS485 driver input |
| 핀 14 | D232A — RS232 driver input, channel A |
| 핀 15 | D232B — RS232 driver input, channel B |
| 핀 16 | RS485_TERM — RS485 termination resistor select |
| 핀 17 | VEE — Charge-pump negative rail (for RS232 drivers) |
| 핀 18 | VCC_232 — RS232 charge-pump positive rail |
| 핀 19 | C1P — Charge-pump flying capacitor terminal |
| 핀 20 | C1N — Charge-pump flying capacitor terminal |
| 핀 21 | C2P — Charge-pump flying capacitor terminal |
| 핀 22 | C2N — Charge-pump flying capacitor terminal |
| 핀 23 | A — RS485 A line (non-inverting) |
| 핀 24 | B — RS485 B line (inverting) |
| 핀 25 | T1IN_A — RS232 driver output A (TX) |
| 핀 26 | R1OUT_A — RS232 receiver input A (RX) |
| 핀 27 | T1IN_B — RS232 driver output B (TX) |
| 핀 28 | R1OUT_B — RS232 receiver input B (RX) |
| 핀 EP | EP — Exposed pad - thermal pad, solder to GND copper pour |
일반적인 애플리케이션
LTC2870IFE#PBF 적합 용도: 7 애플리케이션s: Industrial Multipoint Fieldbus Node, Point-of-Sale (POS) Terminal Serial Interface, RS232-to-RS485 Protocol Converter Bridge, Building Automation and HVAC Controller, Test and Measurement Instrumentation, Industrial Printer and Barcode Reader Controller, Security and Access Control Panel.
Industrial Multipoint Fieldbus Node
The LTC2870 fits industrial multipoint fieldbus nodes because its RS485 channel delivers 20 Mbps data rate and ±25 kV HBM ESD over a 1200 m differential cable with up to 32 unit loads. According to the Analog Devices datasheet, the integrated 120 ohm selectable termination removes external resistor networks and the shared I/O pin map supports mode-switching between RS485 (multi-drop) and RS232 (point-to-point debug) on the same connector. Compared to discrete RS485 transceivers, the LTC2870 reduces BOM by integrating both protocols, important for PLC, motor drive, and process-control front ends where fieldbus robustness is mandatory.
추천
Point-of-Sale (POS) Terminal Serial Interface
POS terminals must connect to legacy RS232 peripherals (PIN pads, scales, receipt printers) and RS485 multi-drop networks (back-office terminals). The LTC2870's pin-configurable multiprotocol support allows a single IC to handle both physical layers from one 3V to 5.5V supply, eliminating an external charge pump. According to the Analog Devices datasheet, the ±25 kV ESD protection on bus pins survives real-world electrostatic discharge from cashiers and peripherals without external TVS arrays, reducing PCB area in space-constrained POS enclosures.
추천
RS232-to-RS485 Protocol Converter Bridge
The LTC2870 can serve as the physical-layer bridge inside an RS232-to-RS485 protocol converter by time-multiplexing its shared I/O between modes. According to the Analog Devices datasheet, firmware controls mode pins to switch between RS232 single-ended and RS485 differential operation, allowing a small embedded MCU to translate packet formats and baud rates. Compared to using two separate transceivers, the LTC2870 shrinks PCB footprint and BOM count, ideal for industrial gateway and protocol-bridge products.
추천
Building Automation and HVAC Controller
Building automation controllers must interface with BACnet MS/TP (RS485) and service-laptop RS232 ports on the same backplane. The LTC2870's shared-pin multiprotocol architecture lets one footprint serve both bus types, with the integrated 120 ohm termination supporting BACnet trunk segments without external resistors. According to the datasheet, the industrial -40 C to +85 C temperature range and ±25 kV ESD rating meet building-automation reliability requirements, while the single 3V to 5.5V supply simplifies 24V-bus-derived power trees common in HVAC panels.
추천
Test and Measurement Instrumentation
Bench instruments (protocol analyzers, data loggers, calibration rigs) often need to communicate to RS232 and RS485 DUTs from one chassis. The LTC2870 supports this via pin-mode switching, with the loopback test mode enabling self-test of the RS232 path without external cabling. According to the Analog Devices datasheet, the 20 Mbps RS485 capability covers high-speed fieldbus capture and the 500 kbps RS232 capability handles legacy instrument links, all from a single 28-pin TSSOP-EP footprint suitable for compact instrument front ends.
추천
Industrial Printer and Barcode Reader Controller
Industrial label printers and barcode readers must communicate over RS485 to factory MES systems and over RS232 to local configuration laptops. The LTC2870's pin-configurable architecture allows one IC to cover both connection types, with the shared-pin design reducing PCB complexity. According to the Analog Devices datasheet, the integrated RS485 termination, ±25 kV ESD, and wide supply range from 3V to 5.5V accommodate industrial 5V/3.3V mixed-rail designs, while the industrial temperature grade suits factory-floor operation.
추천
Security and Access Control Panel
Access-control panels communicate to card readers and sub-panels over RS485 (multi-drop) and to configuration PCs over RS232 (point-to-point). The LTC2870's multiprotocol support consolidates both physical layers on shared I/O lines, allowing one connector to serve either purpose. According to the Analog Devices datasheet, the ±25 kV ESD rating and robust ±15V RS485 common-mode range tolerate cable discharge events on long wiring runs typical in building access systems, and the single 3V to 5.5V supply simplifies battery-backed security-panel power architectures.
추천
추천 제품 요약
엔지니어링 참조 데이터: LTC2870IFE#PBF — 비교, 설계 지침 및 규정 준수 정보.
선택 가이드
대체품과의 비교
| 파라미터 | 이 제품 | LTC2870CFE#PBF | LTC2870IFE | LTC2871IFE#PBF | LTC2871CFE#PBF |
|---|---|---|---|---|---|
| Package | 28-TSSOP-EP (FE) | 28-TSSOP-EP (FE) - same | 28-TSSOP-EP (FE) - same | 28-TSSOP-EP (FE) - same | 28-TSSOP-EP (FE) - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Protocol | RS232 + RS485 (shared I/O) | RS232 + RS485 (shared I/O) | RS232 + RS485 (shared I/O) | RS232 + RS485 (independent I/O) | RS232 + RS485 (independent 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 |
| RS485 Data Rate | 20 Mbps | 20 Mbps | 20 Mbps | 20 Mbps | 20 Mbps |
| ESD (HBM, Bus Pins) | ±25 kV | ±25 kV | ±25 kV | ±25 kV | ±25 kV |
| Operating Temperature | -40 C to +85 C (Industrial) | 0 C to +70 C (Commercial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | 0 C to +70 C (Commercial) |
| Pb-Free / RoHS | Yes (#PBF suffix) | Yes | No (legacy non-Pb-free) | Yes | Yes |
| Integrated RS485 Termination | Yes (120 ohm, pin-selectable) | Yes | Yes | Yes | Yes |
| Duplex Operation | Full Duplex (RS232) / Half or Full (RS485) | Same | Same | Same | Same |
주요 차별점
- Single-supply RS232 operation - no external negative rail (vs Classic MAX232-class RS232 transceivers (e.g., MAX3232))
- Multiprotocol RS232 + RS485 in one IC with shared I/O (vs LTC2871 (independent RS232 + RS485 channels))
- Integrated pin-selectable 120 ohm RS485 termination (vs Discrete RS485 transceivers (e.g., LTC485))
- ±25 kV HBM ESD on bus pins (vs LTC2850 / LTC2851 RS485 transceivers (~±15 kV typical))
설계 노트
Estimated: the LTC2870 28-TSSOP-EP package has a thermal pad (EP) that must be soldered to a continuous ground copper pour on the PCB. Per Analog Devices application guidance, an EP copper area of at least 1 square inch is recommended for industrial temperature operation; failure to solder the EP can raise junction temperature and reduce ESD robustness in field-installed environments. Route shared I/O traces (A, B, RS232 TX/RX) with controlled impedance (100 ohm differential for RS485, 50 ohm single-ended for RS232) and keep them physically separated to avoid cross-protocol coupling.
Place the four charge-pump flying capacitors (C1P/C1N, C2P/C2N) and the VCC/VEE bypass capacitors as close as possible to the LTC2870 pins. Use 0.1 uF X7R ceramics at VCC and VEE for high-frequency decoupling; bulk decoupling (1 uF to 10 uF) handles RS232 driver switching transients. Estimated: at 500 kbps RS232 with full swing, expect ~20 mA transient bursts from the on-chip charge pump; insufficient bulk decoupling can cause VEE droop and inter-symbol jitter.
Do not leave MODE, TE485, TE232A, TE232B, or RE485 floating - tie them to defined logic levels (VCC or GND) through 100 kohm pull-ups or directly to GPIO. Per the Analog Devices datasheet, floating enable pins can cause the driver outputs to switch unpredictably during power-up, potentially asserting RS232 or RS485 onto the bus before the MCU firmware has configured the protocol. Also confirm RS485 termination is enabled only when the LTC2870 sits at a cable end; in mid-bus positions, leave the 120 ohm termination off to avoid bus loading.
Estimated: for RS485 operation at 20 Mbps over long cables (>100 m), place 100 ohm differential termination at the cable ends and minimize stub lengths to <1/10 of the rise time (~5 ns). Use twisted-pair cable with characteristic impedance near 120 ohm (Belden 3106A or equivalent). The LTC2870's ±25 kV ESD rating tolerates cable discharge events, but external TVS protection (e.g., PESD0402-140) is recommended for outdoor installations exposed to lightning-induced surges per IEC 61000-6B generic standards - check your application-specific surge requirement.
규정 준수 정보
RoHS compliant per #PBF suffix designation in Analog Devices part numbering convention. Not AEC-Q100 qualified (industrial transceiver, not automotive). Halogen-free status not explicitly stated in available data.
