SN74AXC8T245RJWR - 8-Bit Dual-Supply Bus Transceiver | Texas Instruments
MPN： SN74AXC8T245RJWR ✓ 啟用中SN74AXC8T245RJWR 概覽
A bus transceiver is a digital logic IC that bridges two buses operating at different voltage levels, allowing data to flow in either direction while protecting each side from incompatible logic levels. The SN74AXC8T245 belongs to TI's AXC family of voltage-level translators, which sit in the broader hierarchy: level translator -> bus transceiver -> logic IC -> semiconductor. The AXC series extends the older AVC and LVC families to lower supply nodes (0.7 V, 0.8 V, 0.9 V) used in modern ASICs, FPGAs, and processors while remaining backward-compatible with industry-standard 1.8 V, 2.5 V, and 3.3 V nodes.
Key features include configurable direction control per direction (DIR pin), an active-low output-enable (OE) input that disables both ports to a high-impedance state, 12 mA balanced output drive strength, and ±24 mA DC latch-up protection. The Ioff circuitry disables the outputs when either VCC rail is powered down, preventing backflow current into a partially powered system - a critical requirement for hot-swap and multi-rail designs.
Technical depth: the AXC architecture uses TI's advanced CMOS process with internal edge-rate accelerators that limit output rise/fall times to reduce EMI while preserving sufficient bandwidth for RGMII and similar multi-hundred-MHz interfaces. The dual-rail design means the DIR and OE control pins are always referenced to VCCA, simplifying control logic on the lower-voltage side.
Typical applications include RGMII level shifting between an SoC and a PHY, I2C/SPI/UART bridging in mixed-voltage embedded systems, memory-bus isolation, and processor-to-peripheral translation in industrial and consumer designs. The 24-pin UQFN (4x2 mm) footprint keeps board area minimal.
Design consideration: always populate both VCCA and VCCB decoupling capacitors (0.1 uF ceramic) within 2 mm of the respective pins, and ensure OE is held low until both rails have ramped to valid levels to avoid bus contention at startup. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
直接替換替代品，適用於 SN74AXC8T245RJWR — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： SN74AXC8T245RJWR （相同外形與佔位） — 差異在於 Direction Control, Function, Number of Elements, Operating Temperature, Output Enable.
SN74AXC8T245RJWRG4
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
SN74AXC8T245RHLR
✅ 直接替換📋 參考替代品（不在目錄中）
SN74AXC8T245PWR
✅ 直接替換📋 參考替代品（不在目錄中）
SN74AVC8T245DGVR
✅ 直接替換聯絡詢價
查看資料表 →CAXC8T245QRHLRQ1
✅ 直接替換📋 參考替代品（不在目錄中）
SN74AXC8T245RJWR 最大額定值與電氣特性
| 功能 | 8-bit dual-supply bus transceiver with voltage translation |
| Logic Family | AXC |
| Number of Bits | 8 |
| Number of Elements | 1 (8 bits per element) |
| Data Flow | Bidirectional, non-inverting |
| 輸出類型 | Tri-State (3-State) |
| Direction Control | DIR pin (per channel group) |
| Output Enable | Active-low OE input |
| VCCA / VCCB Supply Range | 0.65 V to 3.6 V (each port independent) |
| Output Drive Current | 12 mA |
| 工作溫度 | -40C to +125C |
| Ioff Support | Yes (partial-power-down safe) |
| Package Type | UQFN-24 (RJW) 4x2 mm |
| 安裝類型 | Surface Mount |
| RoHS 狀態 | Compliant |
| Lead-Free | Yes |
SN74AXC8T245RJWR 腳位配置
| 腳位 1 | DIR — Direction control input; LOW = B to A, HIGH = A to B |
| 腳位 2 | OE — Output enable, active low; tie HIGH to disable outputs |
| 腳位 3 | A1 — Port A data I/O 1 |
| 腳位 4 | A2 — Port A data I/O 2 |
| 腳位 5 | A3 — Port A data I/O 3 |
| 腳位 6 | A4 — Port A data I/O 4 |
| 腳位 7 | GND — Common ground |
| 腳位 8 | A5 — Port A data I/O 5 |
| 腳位 9 | A6 — Port A data I/O 6 |
| 腳位 10 | A7 — Port A data I/O 7 |
| 腳位 11 | A8 — Port A data I/O 8 |
| 腳位 12 | VCCA — Port A supply voltage, 0.65 V to 3.6 V |
| 腳位 13 | VCCB — Port B supply voltage, 0.65 V to 3.6 V |
| 腳位 14 | B8 — Port B data I/O 8 |
| 腳位 15 | B7 — Port B data I/O 7 |
| 腳位 16 | B6 — Port B data I/O 6 |
| 腳位 17 | B5 — Port B data I/O 5 |
| 腳位 18 | GND — Common ground |
| 腳位 19 | B4 — Port B data I/O 4 |
| 腳位 20 | B3 — Port B data I/O 3 |
| 腳位 21 | B2 — Port B data I/O 2 |
| 腳位 22 | B1 — Port B data I/O 1 |
| 腳位 23 | VCCB — Port B supply voltage (alternate pin) |
| 腳位 24 | VCCA — Port A supply voltage (alternate pin) |
典型應用
SN74AXC8T245RJWR 適用於 7 應用s: RGMII Level Shifting Between SoC and Ethernet PHY, Mixed-Voltage GPIO Expansion in Industrial Systems, Memory-Bus Isolation and Voltage Translation, I2C / SPI / UART Bridge Between Sub-1 V ASIC and 3.3 V Peripheral, JTAG and Debug Port Level Shifting, Server and Networking Card Voltage Adapters, Automotive Infotainment Signal Routing.
RGMII Level Shifting Between SoC and Ethernet PHY
The SN74AXC8T245RJWR bridges the RGMII bus between an SoC and a 1.8 V or 2.5 V Ethernet PHY. Per TI parametric data, the AXC's 0.65 V to 3.6 V dual-rail range covers SoC cores running at 0.8 V or 0.9 V on the A-port while the B-port sits at 1.8 V for the PHY. The 12 mA drive cleanly handles the 125 MHz DDR strobe lanes typical of RGMII without adding significant jitter. DIR control lets designers point A-to-B during TX and B-to-A during RX within the same BOM, eliminating a separate PHY-side translator. Active-low OE also enables two-device bus sharing when designing managed switches.
推薦
Mixed-Voltage GPIO Expansion in Industrial Systems
The SN74AXC8T245RJWR expands 3.3 V or 1.8 V GPIO from a microcontroller to 0.8 V logic peripherals in industrial controller designs. The 0.65 V VCCA minimum supports modern processors running at 0.8 V or 0.9 V cores, while VCCB can be independently set to 1.8 V, 2.5 V, or 3.3 V as required. The 12 mA drive and Ioff support make it robust against capacitive loads and partial-power-down events. Eight channels fit typical SPI or UART bridge use cases when the A-port and B-port voltages differ.
推薦
Memory-Bus Isolation and Voltage Translation
The SN74AXC8T245RJWR isolates and translates memory buses between an MCU at 1.8 V and an SDRAM at 3.3 V, or between an FPGA at 0.9 V and a NOR flash at 1.8 V. AXC's Ioff partial-power-down support is essential for battery-backed designs where the memory rail may drop out while the controller rail stays up. The active-low OE enables external bus arbitration when multiple masters share the same memory island. The -40C to +125C industrial temperature range suits outdoor and factory deployments.
推薦
I2C / SPI / UART Bridge Between Sub-1 V ASIC and 3.3 V Peripheral
The SN74AXC8T245RJWR is a drop-in translator when an FPGA, ASIC, or SoC running at 0.8 V / 0.9 V must communicate with a 3.3 V sensor, ADC, or legacy peripheral over I2C, SPI, or UART. Because the AXC family is bidirectional and configurable per direction via DIR, a single IC handles both TX and RX paths with proper direction control. The 12 mA drive meets the source-current needs of SPI MOSI at 50 MHz, while the fast edge rates keep rise/fall times well within SPI timing budgets. Adding 33 ohm series resistors near the source reduces ringing on long PCB traces.
推薦
JTAG and Debug Port Level Shifting
The SN74AXC8T245RJWR aligns JTAG or SWD debug-port voltages between a debugger at 3.3 V and a target MCU at 0.9 V or 1.8 V. By tying DIR to a dedicated MCU GPIO, the design can dynamically choose whether the translator pushes data toward the target or toward the debugger without manual re-wiring. Ioff prevents backflow into a powered-down target, important when the target is in deep-sleep or off for battery saving. The 24-pin UQFN (4x2 mm) footprint keeps the debug header compact on small IoT PCBs.
推薦
Server and Networking Card Voltage Adapters
The SN74AXC8T245RJWR is used on PCIe, SAS, and storage-controller add-in cards to bridge a 0.85 V or 0.9 V host ASIC to 1.8 V SERDES or 3.3 V peripheral logic. The 12 mA drive and fast edge rates suit SERDES control-plane signals, while the Ioff protection isolates hot-swapped cards from a powered backplane. Multiple AXC devices can share an OE bus, giving the host ASIC system-level control over which card's data lines are connected. The -40C to +125C industrial range covers typical networking-card thermal envelopes.
推薦
Automotive Infotainment Signal Routing
The SN74AXC8T245RJWR routes audio, control, and display data lines in automotive infotainment systems where microcontrollers operate at 3.3 V and codecs or displays require 1.8 V. For AEC-Q100 qualified applications, use the automotive-grade SN74AXC8T245QRHLRQ1 derivative. The industrial temperature range of the standard part suits under-dash infotainment designs, but ECU and under-hood applications require Q1-qualified parts. The small UQFN footprint fits dense head-unit boards.
推薦
推薦產品摘要
工程參考資料，適用於 SN74AXC8T245RJWR — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | SN74AXC8T245RJWRG4 | SN74AXC8T245RHLR | SN74AXC8T245PWR | SN74AVC8T245DGVR | CAXC8T245QRHLRQ1 |
|---|---|---|---|---|---|---|
| Package | UQFN-24 (RJW) 4x2 mm | UQFN-24 (RJW) 4x2 mm - same footprint | VQFN-24 EP (RHL) - larger footprint | TSSOP-24 (PW) - different footprint | TVSOP-24 (DGV) - different footprint | VQFN-24 EP (RHL) - different footprint |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Logic Family | AXC | AXC | AXC | AXC | AVC | AXC |
| Number of Channels | 8 bidirectional | 8 bidirectional | 8 bidirectional | 8 bidirectional | 8 bidirectional | 8 bidirectional |
| VCCA / VCCB Range | 0.65 V to 3.6 V | 0.65 V to 3.6 V | 0.65 V to 3.6 V | 0.65 V to 3.6 V | 1.2 V to 3.6 V | 0.65 V to 3.6 V |
| Output Drive Current | 12 mA | 12 mA | 12 mA | 12 mA | 12 mA | 12 mA |
| Output Type | Tri-State | Tri-State | Tri-State | Tri-State | Tri-State | Tri-State |
| Ioff Support | Yes | Yes | Yes | Yes | Yes | Yes |
| Automotive Grade (AEC-Q100) | No | No | No | No | No | Yes (AEC-Q100) |
主要差異化特點
- True sub-1 V supply support (0.65 V minimum) on both ports (對比SN74AVC8T245DGVR (AVC family))
- Smallest 24-pin footprint within TI's AXC family (對比SN74AXC8T245RHLR (RHL VQFN-24 EP))
- Automotive grade available with same AXC silicon (對比CAXC8T245QRHLRQ1)
設計說明
Place 0.1 uF X7R ceramic decoupling capacitors within 2 mm of both VCCA and VCCB pins, with a 4.7 uF or 10 uF bulk capacitor nearby to suppress transients during output switching. Tie OE to GND through a 100 kohm pull-down to ensure outputs default to high-impedance during power-up, preventing bus contention if the controller has not yet configured its GPIO. Both rails must reach valid levels before DIR toggles, otherwise data corruption may occur.
Route the A-port and B-port signals on separate PCB layers to minimize crosstalk, and place the translator between the two buses. For high-speed RGMII/SERDES control-plane signals, add 33 ohm series damping resistors at each output within 5 mm of the IC to tame transmission-line ringing. Keep ground return paths short and uninterrupted; the UQFN-24 EP thermal pad is critical for thermal dissipation and must be soldered to a flooded ground plane with multiple thermal vias.
Do not assume 5 V tolerance on the inputs: both port inputs are absolute-maximum protected only to 4.6 V regardless of VCC set point, so interfacing a 5 V system requires a translator with true 5 V tolerance (e.g., TXS family). Avoid leaving DIR floating - tie it to VCCA or GND with a 100 kohm resistor to prevent unwanted direction changes during reset. Do not assume Ioff hot-swap capability means hot-insertable - external protection is still required on plug-in cards.
合規資訊
RoHS and REACH compliant per TI product page. Not AEC-Q100 qualified - choose CAXC8T245QRHLRQ1 for automotive grade. Halogen-free per TI product eco info.
