SP334CT-L - Programmable RS-232/RS-485 Transceiver 28-SOIC | MaxLinear
MPN: SP334CT-L ✓ Hoạt độngSP334CT-L Tóm tắt
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.
Bộ thay thế dễ dàng lắp đặt cho SP334CT-L — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
SP334CT-L/TR
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
SP334ET-L
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
SP334CT
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
LTC1334ISW#PBF
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
SP334CT-L Thông số kỹ thuật
| Chức năng | 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 |
| Điện áp cung cấp | 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 |
| Nhiệt độ hoạt động | 0 C to +70 C (commercial) |
| Hộp | 28-SOIC (300 mil, SO-28) |
| Kiểu lắp đặt | Surface Mount |
| Trạng thái RoHS | Compliant |
| Lead-Free | Yes |
Cấu hình chân SP334CT-L
| Chân 1 | T3OUT — RS-232 Driver 3 output |
| Chân 2 | T1OUT — RS-232 Driver 1 output |
| Chân 3 | T2OUT — RS-232 Driver 2 output |
| Chân 4 | R1IN — RS-232 Receiver 1 input |
| Chân 5 | R2IN — RS-232 Receiver 2 input |
| Chân 6 | R3IN — RS-232 Receiver 3 input |
| Chân 7 | R4IN — RS-232 Receiver 4 input |
| Chân 8 | R5IN — RS-232 Receiver 5 input |
| Chân 9 | R5OUT — RS-232 Receiver 5 output (TTL) |
| Chân 10 | R4OUT — RS-232 Receiver 4 output (TTL) |
| Chân 11 | R3OUT — RS-232 Receiver 3 output (TTL) |
| Chân 12 | R2OUT — RS-232 Receiver 2 output (TTL) |
| Chân 13 | R1OUT — RS-232 Receiver 1 output (TTL) |
| Chân 14 | GND — Ground |
| Chân 15 | VCC — +5 V supply input |
| Chân 16 | V+ — Charge-pump generated +5 V to +10 V |
| Chân 17 | C1+ — Charge-pump flying capacitor 1 positive |
| Chân 18 | C1- — Charge-pump flying capacitor 1 negative |
| Chân 19 | C2+ — Charge-pump flying capacitor 2 positive |
| Chân 20 | C2- — Charge-pump flying capacitor 2 negative |
| Chân 21 | V- — Charge-pump generated -5 V to -10 V |
| Chân 22 | A — RS-485 non-inverting driver output / receiver input |
| Chân 23 | B — RS-485 inverting driver output / receiver input |
| Chân 24 | Y — RS-485 non-inverting driver output (redundant with A in some modes) |
| Chân 25 | Z — RS-485 inverting driver output (redundant with B in some modes) |
| Chân 26 | DE — RS-485 driver enable |
| Chân 27 | RE — RS-485 receiver enable (active low) |
| Chân 28 | SLP — Mode select: high = RS-485, low = RS-232 |
Ứng dụng tiêu biểu
SP334CT-L phù hợp cho 6 Áp dụngs: 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.
Được đề xuất
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.
Được đề xuất
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.
Được đề xuất
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.
Được đề xuất
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.
Được đề xuất
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.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho SP334CT-L — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | 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 |
Bảo phân biệt quan trọng
- Integrated RS-232 / RS-485 multi-protocol in one 28-SOIC footprint (vsLTC1334ISW#PBF)
- Slew-rate-limited RS-485 drivers reduce EMI on multi-drop buses (vsMAX485ESA)
- Single 5 V supply eliminates need for bipolar +/- 12 V rails (vsADM5180JPZ)
Ghi chú thiết kế
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.
Thông tin tuân thủ
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.
