TCA9517DGKR - I2C Bus Repeater Level Translator | TI
MPN: TCA9517DGKR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.31 | $1.31 |
| 10 | $1.18 | $11.80 |
| 100 | $0.95 | $95.00 |
| 500 | $0.78 | $390.00 |
| 1,000 | $0.65 | $650.00 |
TCA9517DGKR Overview
A level-translating I2C bus buffer is an interface IC that sits between two segments of an I2C or SMBus, electrically isolating the bus capacitance and logic levels on each side. In the interface IC hierarchy, it belongs to the signal buffer/repeater family of level translators, which sit above simple transistors and below full protocol bridges. By segmenting the bus, the repeater allows longer buses and more devices than the I2C standard capacitance limit would otherwise permit.
Key features include support for both standard-mode (100 kHz) and fast-mode (400 kHz) I2C signaling, an enable (EN) pin for bus isolation and power sequencing, and powered-off high-impedance I2C pins that effectively remove the device from the bus when either supply is absent. The TCA9517 also incorporates an acceleration feature that speeds up the rising edge of SDA and SCL on the B side.
Architecturally, the TCA9517 uses two distinct driver types. The A-side drivers operate from 0.9 V to 5.5 V and drive more current without requiring the buffered-low static offset voltage, so a low on the B side translates to a nearly 0 V hard low on the A side. This accommodates the smaller voltage swings of lower-voltage logic such as 1.2 V or 1.8 V I2C peripherals. The B side retains the static voltage offset needed for hot-swapping and rise-time acceleration.
Typical applications include I2C bus expansion in industrial automation, server and telecom backplane management (SMBus), and level translation between 1.8 V microcontrollers and 3.3 V sensors or EEPROMs.
Design consideration: the A-side output can sink more current than a plain MOSFET translator, so pay attention to total bus capacitance per segment; keep pull-up resistor values sized per segment rather than one pair for the whole bus.
This page synthesizes distributor pricing, verified drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for TCA9517DGKR — 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 TCA9517DGKR (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:
TCA9517ADGKR
✅ Drop-In📋 Reference alternative (not in catalog)
TCA9511ADGKR
✅ Drop-In📋 Reference alternative (not in catalog)
PCA9517DGKR
✅ Drop-In📋 Reference alternative (not in catalog)
TCA9517DGKR Specifications
| Function | Level-translating I2C/SMBus buffer, repeater |
| Channels | 2 (bidirectional SDA, SCL) |
| Circuits | 1 |
| Maximum Operating Frequency | 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 |
| Supply Restriction | VCCA <= VCCB |
| Enable Pin | Yes (EN) |
| Powered-Off High Impedance | Yes (I2C pins high-Z when supply off) |
| Response Time | 110 ns (typical, per TCA9517 family data) |
| Package | 8-VSSOP (DGK), 3.00 mm width |
| Mounting Type | Surface Mount |
| MSL Level | 1 (260C unlimited) |
| RoHS Status | Compliant |
TCA9517DGKR Pin Configuration
| Pin 1 | VCCA — A-side supply voltage, 0.9 V to 5.5 V |
| Pin 2 | A1 — SDA, A-side serial data (low-voltage side) |
| Pin 3 | A2 — SCL, A-side serial clock (low-voltage side) |
| Pin 4 | GND — Ground reference |
| Pin 5 | EN — Enable input; connects or isolates the two bus segments |
| Pin 6 | B2 — SCL, B-side serial clock (higher-voltage side) |
| Pin 7 | B1 — SDA, B-side serial data (higher-voltage side) |
| Pin 8 | VCCB — B-side supply voltage, 2.7 V to 5.5 V (VCCA <= VCCB) |
Typical Applications
TCA9517DGKR is suitable for 6 applications: Industrial Automation I2C Bus Expansion, Server and Telecom Backplane SMBus Management, 1.8V to 3.3V I2C Level Translation, Battery-Powered and Portable Devices, Networking Equipment Fan and Power Supervision, Test and Measurement Instrumentation.
Industrial Automation I2C Bus Expansion
In factory automation and process control systems, a single I2C master often must reach many sensors and actuators spread across a backplane or cabinet, quickly exceeding the I2C bus capacitance limit of 400 pF. The TCA9517DGKR solves this by segmenting the bus: each side is actively driven, so capacitance and pull-up sizing are managed per segment. Its 400 kHz Fast-mode support keeps scan cycles fast across long runs, while the EN pin lets the controller isolate a faulted segment for hot servicing. The powered-off high-impedance bus pins mean modules can be inserted or removed without corrupting the live bus, a practical necessity in modular I/O racks.
Recommended
Server and Telecom Backplane SMBus Management
Server chassis and telecom shelves use SMBus for power-supply monitoring, fan controllers, and EEPROM DIMM management, where bus length and device count routinely exceed unbuffered limits. The TCA9517DGKR buffers shelf-management segments while meeting SMBus timing with 400 kHz capability and B-side rise-time acceleration. Its static voltage offset on the B side prevents latch-up during hot-swap insertion of line cards, and powered-off high impedance ensures a powered-down blade does not load the management bus. Segmenting the shelf into A-side card buses and B-side backplane bus keeps each segment's capacitance within specification and isolates electrical faults.
Recommended
1.8V to 3.3V I2C Level Translation
Many modern sensors, touch controllers, and FRAM memories run at 1.8 V while the host MCU or SoC I2C controller runs at 3.3 V. The TCA9517DGKR bridges this gap because its A-side driver operates from 0.9 V and drives a hard, near-0V low, accommodating the small voltage swings of low-voltage logic, while the B side runs at 2.7 V to 5.5 V. Unlike a passive MOSFET translator, it actively drives both rails, preserving rise times at 400 kHz even with several devices and modest trace lengths. Place it near the connector or module boundary, with per-segment pull-ups, so each voltage domain sees correctly sized pull-up resistors.
Recommended
Battery-Powered and Portable Devices
In portable and battery-powered designs, the TCA9517DGKR enables a low-voltage 1.2 V to 1.8 V PMIC-side I2C domain to communicate with 3.3 V peripherals such as fuel gauges, audio codecs, and ambient-light sensors. Its enable pin supports power sequencing and permits the controller to gate the buffer off in deep-sleep states, and the powered-off high-impedance I2C pins guarantee the bus is not loaded when supplies collapse. Because the device occupies only an 8-VSSOP 3 mm package with MSL 1 handling, it fits compact wearable and handheld layouts with minimal assembly constraints.
Recommended
Networking Equipment Fan and Power Supervision
Routers, switches, and optical line cards use I2C/SMBus to monitor fan tachometers, temperature sensors, and hot-swap power modules. The TCA9517DGKR buffers the monitoring bus between the management controller and chassis peripherals, with 400 kHz speed enabling rapid polling of dozens of devices. The EN pin allows firmware to segment the bus during troubleshooting or firmware updates of downstream devices, and powered-off high impedance lets cards boot or power down independently without stalling the shared bus. Hard A-side lows ensure reliable logic thresholds over long, noisy backplane traces typical of telecom chassis.
Recommended
Test and Measurement Instrumentation
Bench instruments and modular measurement systems often mix 1.8 V, 3.3 V, and 5 V I2C peripherals for calibration EEPROMs, digitizer configuration, and front-end control. The TCA9517DGKR provides clean level translation across these domains with its 0.9 V to 5.5 V A-side and 2.7 V to 5.5 V B-side ranges, while active drive eliminates the marginal thresholds that passive translators exhibit on capacitively heavy front-panel buses. Powered-off high impedance prevents a module powering up from disturbing other modules, and the enable pin lets system firmware quarantine a misbehaving slot without affecting the rest of the instrument.
Recommended
Recommended Products Summary
Engineering reference data for TCA9517DGKR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TCA9517ADGKR | TCA9511ADGKR | PCA9517DGKR |
|---|---|---|---|---|
| Package | 8-VSSOP (DGK) | 8-VSSOP (DGK) - same | 8-VSSOP (DGK) - same | 8-VSSOP (DGK) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | NXP Semiconductors |
| VCCA Range | 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 |
| VCCB Range | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V |
| Enable Pin | Yes | Yes | Yes | Yes |
Key Differentiators
- Errata-free operation versus the original device (vs PCA9517DGKR)
- Wide low-voltage A-side support (vs TCA9511ADGKR)
- A-suffix upgrade available in the same footprint (vs TCA9517ADGKR)
Design Notes
Observe the supply restriction VCCA <= VCCB at all times, including power sequencing and fault conditions. If VCCA exceeds VCCB, the device may not operate within datasheet limits. Design the power rails so the A-side supply is always at or below the B-side supply, and verify cold-start sequencing with an oscilloscope during bring-up. Do not connect the EN pin to a rail that violates this relationship during startup.
Because the TCA9517 actively drives both segments, treat the A side and B side as two independent buses: place pull-up resistors on each segment sized for that segment's capacitance and voltage (for example, 4.7k at 3.3 V or 10k at 1.8 V), rather than a single pair spanning the device. Place the TCA9517 close to the segment boundary or connector, keep SDA and SCL traces short and matched, and use the VSSOP exposed-lead footprint with solid GND on pin 4 as the reference.
The TCA9517 is not a transparent repeater - it prevents a low on one side from being immediately reflected on the other (the low is retransmitted), so standard I2C multi-master arbitration across the buffer is not supported. Reserve this device for single-master segments or segments where arbitration does not cross the buffer. Also note the B-side static voltage offset: slaves on the B side must not attempt to drive below the offset low level; most dedicated I2C peripherals comply, but bit-banged firmware GPIO implementations may not.
Compliance Information
RoHS compliant and MSL 1 (260C unlimited) per distributor data (PartGenie). REACH, halogen-free, and conflict-minerals status not stated in provided data.
