SP334CT-L - Programmable RS-232/RS-485 Transceiver 28-SOIC | MaxLinear
N.º da peça: SP334CT-L ✓ Ativo| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $4.95 | $4,95 |
| 10 | $4.46 | $44,60 |
| 100 | $3.96 | $396,00 |
| 500 | $3.56 | $1.780,00 |
| 1.000 | $3.17 | $3.170,00 |
SP334CT-L Visão geral
A multi-protocol transceiver IC combines a UART/serial-port line interface that bridges an MCU's asynchronous logic-level serial port to industry-standard differential or single-ended physical-layer signaling used in industrial, point-of-sale, and embedded-networking equipment. The SP334 family sits in the broader Interface IC hierarchy (line transceiver > multiprotocol transceiver > serial interface > wired connectivity IC) and is commonly used to consolidate RS-232 and RS-485 ports onto one PCB footprint when both legacy and industrial buses must coexist.
Key features include on-board charge-pump DC-DC converters that generate the +/- 5 V to +/- 10 V RS-232 levels from a single 5 V supply, true fail-safe receiver inputs on the RS-485 path (guaranteed logic-high output with open or shorted inputs), thermal-shutdown protection, and a hardware strap (pin 28 / SLP) that selects between RS-232 and RS-485 modes. The internal drivers use slew-rate control on the RS-485 side to limit harmonic content and reduce reflections on unterminated stubs. Driver and receiver enable pins allow half-duplex RS-485 direction control while preserving RS-232 simplex operation.
The SP334 architecture uses a BiCMOS process that integrates charge-pump capacitors externally but keeps the charge-pump switching nodes, drivers, and receivers on the same die. This minimizes external component count to typically six 0.1 uF pump capacitors plus standard bypass. The RS-485 drivers meet the TIA/EIA-485-A differential output swing of at least 1.5 V across a 27 ohm load and the receiver thresholds follow the +/- 200 mV standard with the additional fail-safe bias.
Typical applications include multi-drop RS-485 industrial fieldbus nodes, point-of-sale terminals that require RS-232 for legacy peripherals, factory automation controllers, and HVAC or building-automation gateways. Designers choose the SP334 when a single BOM line item must cover both a maintenance-port RS-232 connection and an RS-485 trunk to neighboring equipment.
A key design consideration is the charge-pump capacitor selection: 0.1 uF ceramics with low ESR and at least 16 V rating are recommended. Pump frequency is typically 1 MHz; bypassing the V+ and V- pins with 0.1 uF plus 10 uF bulk capacitors improves RS-232 output symmetry under heavy load. The mode-select pin must be tied high or low and not left floating during operation.
This page synthesizes distributor pricing, parametric drop-in alternatives, and application-level design notes not consolidated in the manufacturer datasheet, giving engineers a faster sourcing decision path for the SP334CT-L.
Alternativas drop-in para SP334CT-L — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
SP334CT-L/TR
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
SP334ET-L
✅ Drop-In ⚠️ Especificações não verificadas📋 Alternativa de referência (fora do catálogo)
SP334CT
✅ Drop-In ⚠️ Especificações não verificadas📋 Alternativa de referência (fora do catálogo)
LTC1334ISW#PBF
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
SP334CT-L Especificações
| Função | Programmable RS-232 / RS-485 Transceiver |
| Protocol | RS-232, RS-485 (multi-protocol) |
| Number of Drivers | 3 RS-232 / 2 RS-485 |
| Number of Receivers | 5 RS-232 / 2 RS-485 |
| Tensão de alimentação | 4.75 V to 5.25 V |
| RS-232 Data Rate | Up to 230 kbps |
| RS-485 Driver Data Rate | Up to 5 Mbps (slew-rate limited) |
| RS-232 Driver Output Swing | Minimum +/- 5 V into 3 kohm load |
| RS-485 Differential Output | >= 1.5 V across 27 ohm load |
| Receiver Fail-safe | Yes (RS-485 path, logic high on open/short) |
| Receiver Hysteresis | Typical 50 mV |
| Temperatura de operação | 0 C to +70 C (commercial) |
| Encapsulamento | 28-SOIC (300 mil, SO-28) |
| Tipo de montagem | Surface Mount |
| Status RoHS | Compliant |
| Lead-Free | Yes |
Configuração de pinos do SP334CT-L
| Pino 1 | T3OUT — RS-232 Driver 3 output |
| Pino 2 | T1OUT — RS-232 Driver 1 output |
| Pino 3 | T2OUT — RS-232 Driver 2 output |
| Pino 4 | R1IN — RS-232 Receiver 1 input |
| Pino 5 | R2IN — RS-232 Receiver 2 input |
| Pino 6 | R3IN — RS-232 Receiver 3 input |
| Pino 7 | R4IN — RS-232 Receiver 4 input |
| Pino 8 | R5IN — RS-232 Receiver 5 input |
| Pino 9 | R5OUT — RS-232 Receiver 5 output (TTL) |
| Pino 10 | R4OUT — RS-232 Receiver 4 output (TTL) |
| Pino 11 | R3OUT — RS-232 Receiver 3 output (TTL) |
| Pino 12 | R2OUT — RS-232 Receiver 2 output (TTL) |
| Pino 13 | R1OUT — RS-232 Receiver 1 output (TTL) |
| Pino 14 | GND — Ground |
| Pino 15 | VCC — +5 V supply input |
| Pino 16 | V+ — Charge-pump generated +5 V to +10 V |
| Pino 17 | C1+ — Charge-pump flying capacitor 1 positive |
| Pino 18 | C1- — Charge-pump flying capacitor 1 negative |
| Pino 19 | C2+ — Charge-pump flying capacitor 2 positive |
| Pino 20 | C2- — Charge-pump flying capacitor 2 negative |
| Pino 21 | V- — Charge-pump generated -5 V to -10 V |
| Pino 22 | A — RS-485 non-inverting driver output / receiver input |
| Pino 23 | B — RS-485 inverting driver output / receiver input |
| Pino 24 | Y — RS-485 non-inverting driver output (redundant with A in some modes) |
| Pino 25 | Z — RS-485 inverting driver output (redundant with B in some modes) |
| Pino 26 | DE — RS-485 driver enable |
| Pino 27 | RE — RS-485 receiver enable (active low) |
| Pino 28 | SLP — Mode select: high = RS-485, low = RS-232 |
Aplicações típicas
SP334CT-L é adequado para 6 aplicaçãos: Multi-Drop RS-485 Industrial Fieldbus Nodes, Point-of-Sale (POS) Terminal Multi-Protocol Serial Port, Factory Automation Controller Gateway, HVAC and Building Automation Bus Nodes, Embedded Networking Serial Console with RS-485 Trunk, Legacy Industrial Equipment Multi-Protocol Adapter.
Multi-Drop RS-485 Industrial Fieldbus Nodes
The SP334CT-L is well suited for RS-485 multi-drop fieldbus nodes because its RS-485 path supports up to 5 Mbps with slew-rate-limited drivers that reduce reflections on long stubs. The integrated fail-safe receiver bias eliminates the need for external pull-up / pull-down resistors on the A/B differential pair, which simplifies PCB layout and reduces BOM. Connected to a 5 V MCU UART through TTL-level RX/TX pins, the IC delivers >= 1.5 V differential output across 27 ohm, comfortably meeting TIA/EIA-485-A across 32 unit loads. Trade-off: switching between RS-232 and RS-485 modes via the SLP pin adds firmware coordination overhead.
Recomendado
Point-of-Sale (POS) Terminal Multi-Protocol Serial Port
POS terminals must support legacy RS-232 peripherals (barcode scanners, receipt printers, PIN pads) while also connecting to RS-485 trunk networks for back-office inventory lines. The SP334CT-L's hardware mode-select strap lets a single 28-SOIC footprint serve both, reducing PCB area versus placing a dedicated RS-232 IC plus a dedicated RS-485 IC. RS-232 drivers deliver 230 kbps and +/- 5 V swing into 3 kohm loads, comfortably meeting EIA/TIA-232E for cable runs up to 15 m. Trade-off: charge-pump capacitors (six 0.1 uF) consume PCB area on the bottom layer.
Recomendado
Factory Automation Controller Gateway
Factory automation gateways aggregate data from RS-485 sensor clusters and expose a local RS-232 maintenance port for technician laptops. The SP334CT-L fits this role because the same IC routes either protocol to the host MCU based on the SLP pin state, and its 0 C to +70 C commercial temperature range covers most indoor cabinet environments. Half-duplex RS-485 direction control is handled by the integrated driver / receiver enable pins, simplifying MCU firmware. Trade-off: for outdoor cabinets, the SP334ET-L extended-temperature variant should be selected instead.
Recomendado
HVAC and Building Automation Bus Nodes
HVAC controllers and building-automation bus nodes typically expose both RS-485 trunks to VAV / FCU equipment and RS-232 commissioning ports. The SP334CT-L consolidates these into one 28-SOIC IC, freeing board real estate for analog sensor inputs. The fail-safe RS-485 receiver prevents bus hangs when a downstream node is powered off or its cable is disconnected, which is critical in 24/7 building operations. Trade-off: the SP334 does not include isolation, so adding an isolation barrier (e.g., ADuM1411) is required when crossing HVAC safety domains.
Recomendado
Embedded Networking Serial Console with RS-485 Trunk
Embedded routers and serial-console servers often expose an RS-232 console port for technician access and an RS-485 trunk to downstream sensor / telemetry nodes. The SP334CT-L addresses both with one footprint, simplifying the BOM and the layout review. The 230 kbps RS-232 rate is more than sufficient for human-typing console interaction, and the 5 Mbps RS-485 rate supports high-throughput telemetry packets. Trade-off: 5 Mbps RS-485 requires careful PCB trace impedance (100 ohm differential) and 120 ohm termination at cable ends.
Recomendado
Legacy Industrial Equipment Multi-Protocol Adapter
Adapters that bridge legacy RS-232 PLCs to RS-485 SCADA networks rely on multiprotocol transceivers like the SP334CT-L to support both ends of the conversion in a single IC. The hardware mode-select strap enables the adapter to act as either protocol side without firmware-driven muxing. The single 5 V supply simplifies the power tree, especially in adapters powered from USB or 24 V industrial rails through a small buck regulator. Trade-off: PLCC-packaged legacy variants of multiprotocol ICs (e.g., ADM5180JPZ) cannot be retrofitted without PCB rework.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para SP334CT-L — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | SP334CT-L/TR | SP334ET-L | SP334CT | LTC1334ISW#PBF | ADM5180JPZ |
|---|---|---|---|---|---|---|
| Brand | MaxLinear | MaxLinear | MaxLinear | MaxLinear | Analog Devices | Analog Devices |
| Package | 28-SOIC | 28-SOIC | 28-SOIC | 28-SOIC | 28-SOIC | 28-PLCC |
| Function | RS-232 / RS-485 programmable | RS-232 / RS-485 programmable | RS-232 / RS-485 programmable | RS-232 / RS-485 programmable | RS-232 / RS-485 programmable | RS-232 / RS-423 / RS-485 programmable |
| 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 |
Principais diferenciais
- Integrated RS-232 / RS-485 multi-protocol in one 28-SOIC footprint (vs LTC1334ISW#PBF)
- Slew-rate-limited RS-485 drivers reduce EMI on multi-drop buses (vs MAX485ESA)
- Single 5 V supply eliminates need for bipolar +/- 12 V rails (vs ADM5180JPZ)
Notas de projeto
Estimated: the SP334CT-L draws approximately 20 mA quiescent current in RS-232 mode at 5 V, so a 100 mA local regulator budget is sufficient. Place 0.1 uF X7R ceramic bypass capacitors on VCC, V+, and V- within 3 mm of the IC pins, and add a 10 uF bulk capacitor on V+ and V- to reduce RS-232 output ripple under heavy capacitive load. The charge-pump switches at roughly 1 MHz, so the bypass capacitors must have low ESR to avoid charge-pump dropout.
The SLP mode-select pin (pin 28) must be tied hard to VCC (RS-485 mode) or GND (RS-232 mode) and never left floating, otherwise the IC may oscillate between modes or enter an undefined state. The RS-485 DE and RE pins should be tied to GND and VCC respectively during reset to keep the RS-485 drivers tri-stated and avoid bus contention. Do not exceed 5.5 V on VCC; the on-board charge pump cannot tolerate over-voltage and the ESD cells may latch.
Route the RS-485 A / B differential pair as a 100 ohm impedance-controlled differential microstrip, with 120 ohm termination resistors at each end of the cable run. Keep the SP334 ground plane continuous under the charge-pump capacitors (C1+, C1-, C2+, C2-) to provide a low-impedance return path for the 1 MHz switching currents. Separate the RS-232 driver outputs from the RS-485 differential pair by at least 3 mm to avoid capacitive crosstalk on long cables.
Informações de conformidade
RoHS compliant per MaxLinear product page. The -L suffix denotes lead-free finish. Not AEC-Q100 qualified - choose SP334ET-L for extended industrial temperature but not full automotive qualification.
