TCA9517DGKRQ1 - Automotive I2C Level-Shifting Buffer | TI
MPN: TCA9517DGKRQ1 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.72 | $0.72 |
| 10 | $0.64 | $6.40 |
| 100 | $0.52 | $52.00 |
| 500 | $0.49 | $245.00 |
| 1,000 | $0.46 | $460.00 |
TCA9517DGKRQ1 Overview
An I2C bus buffer, also called a level translator or bus repeater, is an interface IC that sits between two segments of an I2C or SMBus serial bus. Its role in the interface IC hierarchy is to isolate bus capacitance, allowing longer or more heavily loaded buses, and to translate logic voltage levels between devices powered from different supply rails, such as a 1.8V microcontroller talking to 5V peripherals.
Key features include bidirectional voltage-level translation between low voltages down to 0.9 V on side A and 2.7 V to 5.25 V on side B, support for both standard-mode (100 kHz) and fast-mode (400 kHz) I2C plus SMBus, and a powered-off high-impedance state that isolates both bus segments when either supply rail is absent. The enable (EN) pin provides additional bus control, and open-drain I/O structures preserve the wired-AND nature of I2C.
Technically, the TCA9517-Q1 drives both sides of the bus, refreshing rise times and removing the cumulative load of stubs and cables. Unlike passive FET level shifters, it does not trade drive strength for level translation, so clock stretching and multi-master arbitration are preserved. It supports up-translation, down-translation, and same-level buffering.
Typical applications include automotive body electronics and infotainment I2C bus extension, PMBus/SMBus power-supply management in industrial systems, and level translation between 1.8V or 3.3V MCUs and 5V sensors or EEPROMs.
Design consideration: because the device drives each side actively, do not connect the A and B sides to the same bus segment, and keep EN tied low until both supply rails are stable to avoid bus latch-up during power sequencing.
This page synthesizes distributor pricing, drop-in alternatives, pinout data, and practical design notes not found in the manufacturer datasheet alone. Pricing shown as of 2026-10-19.
Drop-in alternatives for TCA9517DGKRQ1 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with TCA9517DGKRQ1 (same form factor and footprint) — differing in Function, Package, Number of Channels, Enable Pin, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
TCA9517ADGKRQ1
✅ Drop-In📋 Reference alternative (not in catalog)
TCA9517DGKR
✅ Drop-In✓ In Stock
$0.65 / Unit
View Datasheet →TCA9517ADGKR
✅ Drop-In📋 Reference alternative (not in catalog)
PCA9517DGKR
✅ Drop-In📋 Reference alternative (not in catalog)
TCA9517DGKRQ1 Specifications
| Function | Level-translating I2C/SMBus buffer/repeater |
| Number of Channels | 2 (1 bidirectional circuit) |
| Data Rate | 400 kHz (fast-mode I2C) |
| VCCA Supply Range | 0.9 V to 5.5 V |
| VCCB Supply Range | 2.7 V to 5.5 V |
| Translation Direction | Bidirectional (up and down) |
| Protocol Support | I2C, SMBus |
| Powered-Off High Impedance | Yes |
| Automotive Qualification | AEC-Q100 qualified |
| Operating Temperature | -40C to +125C |
| Package | VSSOP (DGK), 8 pins |
| Mounting Type | Surface Mount |
| Output Type | Open-drain |
| Enable Pin | Yes (EN) |
| RoHS Status | Compliant |
| Bus Capacitance Isolation | Yes (buffer/repeater function) |
TCA9517DGKRQ1 Pin Configuration
| Pin 1 | VCCA — A-side supply voltage, 0.9 V to 5.5 V |
| Pin 2 | A1 — A-side serial data (SDA1), open-drain |
| Pin 3 | A2 — A-side serial clock (SCL1), open-drain |
| Pin 4 | GND — Ground |
| Pin 5 | EN — Enable input, connects A and B sides when high |
| Pin 6 | B2 — B-side serial clock (SCL2), open-drain |
| Pin 7 | B1 — B-side serial data (SDA2), open-drain |
| Pin 8 | VCCB — B-side supply voltage, 2.7 V to 5.5 V |
Typical Applications
TCA9517DGKRQ1 is suitable for 6 applications: Automotive Body Electronics I2C Bus Extension, 1.8V MCU to 5V Peripheral Level Translation, PMBus / SMBus Power Supply Management, Industrial Sensor Hub Networks, Infotainment and Display Module Buses, Mixed-Voltage GPIO and EEPROM Expansion.
Automotive Body Electronics I2C Bus Extension
In automotive body control modules, door zones, and lighting nodes, I2C buses must cross connectors and cable harnesses that add capacitance well beyond the 400 pF limit. The TCA9517DGKRQ1 buffers the bus so each side is actively driven, letting a long harness hang on one side without degrading rise times on the controller side. Its AEC-Q100 qualification and -40C to +125C rating directly match under-hood and in-cabin temperature environments. Because it provides powered-off high-impedance I/O, nodes that lose supply do not load or clamp the bus. Typical benefit: placement mid-bus doubles achievable node count and cable length at full 400 kHz speed.
Recommended
1.8V MCU to 5V Peripheral Level Translation
Modern microcontrollers running at 1.8 V often need to talk to 5 V EEPROMs, RTCs, sensors, or PMBus power supplies. The TCA9517DGKRQ1 accepts VCCA down to 0.9 V, so a 1.8 V bus on the A side up-translates cleanly to a 2.7-5.25 V bus on the B side at 400 kHz. Unlike discrete MOSFET level shifters, the active buffer does not attenuate drive strength, so rise times remain sharp with standard 4.7 kohm pull-ups. The powered-off high-impedance feature prevents back-powering the 1.8 V domain through clamp diodes when the 5 V rail is up first - a common failure mode with passive translators.
Recommended
PMBus / SMBus Power Supply Management
Server, telecom, and industrial power supplies use SMBus for telemetry and control. The TCA9517DGKRQ1 isolates the management bus from power-supply module buses, refreshing drive on each segment and translating between 3.3 V backplane management rails and 5 V module-side rails. Its 400 kHz support matches SMBus timing, and the open-drain wired-AND structure preserves arbitration when multiple managers share the bus. The EN pin allows a hot-swap controller or CPLD to disconnect a segment during card insertion, preventing partial-power bus contention. Powered-off high-impedance also ensures a blanked supply module never loads the shared management plane.
Recommended
Industrial Sensor Hub Networks
Factory equipment often chains multiple I2C sensors - temperature, pressure, current - on long backplane runs that exceed raw I2C capacitance limits. Placing a TCA9517DGKRQ1 between the controller segment and the sensor field segment lets each side meet timing independently. Its -40C to +125C rating covers unconditioned industrial cabinets, and the 0.9 V minimum VCCA supports both legacy 3.3 V and new low-voltage controller domains. Because the buffer re-drives the bus, standard 4.7-10 kohm pull-ups remain valid regardless of segment length, avoiding per-node RC tuning. Segment isolation also simplifies fault localization during commissioning.
Recommended
Infotainment and Display Module Buses
Automotive infotainment head units and display modules use I2C for touchscreen controllers, backlight drivers, and EEPROM configuration memory across several boards. The TCA9517DGKRQ1 buffers buses between the SoC board and display/RGB LED driver boards, translating between 1.8 V SoC-side I2C and 3.3 V or 5 V module-side buses at 400 kHz. AEC-Q100 qualification satisfies infotainment OEM requirements, and the powered-off high-impedance state prevents a sleeping display module from holding the host bus low during selective power-down, a known cause of boot faults. One buffer per bus segment keeps each module hot-pluggable.
Recommended
Mixed-Voltage GPIO and EEPROM Expansion
When a 3.3 V or 1.8 V processor must access 5 V I2C EEPROMs, security ICs, or legacy peripherals, the TCA9517DGKRQ1 provides the translation bridge while also isolating the often long and heavily loaded peripheral bus. The device preserves clock stretching that many EEPROMs rely on during internal write cycles, which simple unidirectional translators break. Powered-off high-impedance I/O means peripherals on an independently switched 5 V rail disappear from the bus rather than parasitically powering up through their pull-ups. At 400 kHz full speed, configuration reads during boot remain fast, and one 8-pin device covers the entire 2-wire interface.
Recommended
Recommended Products Summary
Engineering reference data for TCA9517DGKRQ1 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TCA9517ADGKRQ1 | TCA9517DGKR | TCA9517ADGKR | PCA9517DGKR |
|---|---|---|---|---|---|
| Package | VSSOP-8 (DGK) | VSSOP-8 (DGK) - same | VSSOP-8 (DGK) - same | VSSOP-8 (DGK) - same | VSSOP-8 equivalent - verify suffix footprint |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | NXP Semiconductors |
| Data Rate | 400 kHz | 400 kHz | 400 kHz | 400 kHz | 400 kHz |
| VCCA Range (Low-Voltage Side) | 0.9 V to 5.5 V | 0.9 V to 5.5 V | 0.9 V to 5.5 V | 0.9 V to 5.5 V | 0.9 V to 5.5 V |
| Powered-Off High Impedance | Yes | Yes | Yes | Yes | Yes |
Key Differentiators
- Full automotive qualification (vs TCA9517DGKR)
- 0.9 V minimum VCCA (vs PCA9517DGKR)
- Powered-off high-impedance isolation (vs Discrete FET level shifters)
Design Notes
Never connect the A side and B side to the same bus net. The TCA9517-Q1 actively drives each side, so bridging them creates drive contention and possible latch-up during arbitration. Treat the device as a segment boundary: pull-ups are required on BOTH sides independently (typically 4.7 kohm to 10 kohm at 3.3 V). Also hold EN low until both VCCA and VCCB are stable; the datasheet application section recommends enabling only after power-good to avoid spurious bus activity during power sequencing.
Place 0.1 uF ceramic decoupling capacitors within 2 mm of both VCCA (pin 1) and VCCB (pin 8), each with a solid via to the ground plane. Keep the A-side and B-side traces physically separated to minimize crosstalk and make the segment boundary visible for debug. The VSSOP (DGK) package has a 0.65 mm lead pitch - use a solder-mask-defined land pattern per the TI datasheet footprint and consider thermal relief only on the ground pad to ease rework.
Each TCA9517-Q1 buffer adds a small propagation delay on every bus direction change, which accumulates on longer chains. Limit cascaded buffers to two levels for reliable 400 kHz operation and verify rise/fall times with an oscilloscope under worst-case bus load. Estimate pull-up values from total segment capacitance: Rise time approximately 0.8473 x Rp x Cb; keep rise time under 300 ns for fast-mode. If clock stretching is used by slaves, confirm the master supports the extended low period through the buffer.
Compliance Information
AEC-Q100 qualification confirmed by TI product page listing. RoHS/lead-free status inferred from active TI production status; verify REACH and halogen-free status on ti.com quality pages.
