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TSSOP-24 · TCA9548A
ActiveI2C Switch / Multiplexer (8-ch)
TCA9548A
Texas Instruments · TSSOP-24 · I2C Switch / Multiplexer (8-ch)
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Overview
The TCA9548A is TI's 8-channel I2C-bus switch, and it solves two of the most annoying problems in multi-device I2C systems: address collisions and bus capacitance. It sits between one master and up to eight downstream buses; a single control-register write connects any combination of channels (or none), and disconnected channels present high impedance so devices on them neither load the bus nor respond to traffic. This lets you place eight identical sensors — each stuck at a fixed address like 0x29 — on eight channels and read them sequentially through one master.
The switch operates from 1.65 V to 5.5 V, supports Fast-mode 400 kHz signaling, and passes bus levels through with low on-resistance FET switches; pull-up resistors on each segment should be sized for that segment. Three address pins place up to eight TCA9548A devices at 0x70-0x77, so a single bus can fan out to 64 sub-buses. Crucially, it includes both power-up reset and a dedicated active-low RESET pin: if a downstream slave wedges the bus mid-transaction (a classic I2C failure mode), pulsing RESET disconnects all channels and restores the master side — no power cycle needed.
Designers comparing parts should note the TCA9545A (4 channels, adds four interrupt lines) and PCA9548A (NXP original of the same family, fully compatible). TI and NXP parts are dual-sourced and interchangeable in practice. Counterfeit risk is low-to-moderate; remarked units typically fail channel isolation, which shows up as ghost responses during address scans. Shenzhen stock is plentiful, MOQ from cut tape to full reels of 2,500 pcs TSSOP-24.
Key Features
- 8 independent I2C channels, any combination enabled by one register write
- Resolves fixed-address collisions — run 8 identical sensors on one master
- 1.65-5.5 V supply, 400 kHz Fast-mode, low Ron FET switches
- Dedicated RESET pin plus power-up reset recovers stuck-bus lockups
Typical Applications
- Multi-sensor acquisition rigs with identical-address IMUs and ToF sensors
- Server management buses isolating DIMM SPD, FRU EEPROMs and sensors
- Test fixtures and ATE probing many DUTs from one I2C master
- Reducing bus capacitance in large building-automation and avionics systems
- Lab instruments multiplexing ADC/DAC evaluation boards
Specifications
- Number of Channels
- 8
- Interface
- I2C (up to 400 kHz)
- Supply Voltage
- 1.65 to 5.5 V
- I2C Address Range
- 0x70 to 0x77 (A0-A2)
- Reset
- Active-Low RESET Pin + Power-Up Reset
- Channel Selection
- Any Combination via Control Register
- Bus Isolation (Off State)
- High Impedance, Low Leakage
- Operating Temperature
- -40 to 85 °C
- Pins
- 24
- RoHS
- Compliant
Procurement Tips
When multiplexing high-speed sensors, keep the TCA9548A physically close to the slaves and use one pull-up network per segment; buy TI and NXP PCA9548A from us as approved alternates so allocation on one vendor never stops your line.
Frequently Asked Questions
What is the difference between TCA9548A and TCA9545A?
TCA9545A has 4 channels and adds interrupt pass-through with four independent INT lines; TCA9548A has 8 channels but no interrupt aggregation. Choose the 9548A for pure fan-out density, the 9545A when slaves must signal the master asynchronously.
Is the TCA9548A compatible with the NXP PCA9548A?
Yes — TI acquired this design lineage and the parts are functionally and pinout compatible (TSSOP-24). The register map is identical, so firmware runs on either vendor unmodified; keep both approved on your AVL.
Does the TCA9548A level-translate between 1.8 V and 5 V buses?
Not like a dedicated translator, but the switches are bidirectional FETs that pass whatever levels appear, and each side is pulled up to its own rail. TI specifies operation with different voltages on either side within the 1.65-5.5 V envelope — pull up each segment independently and verify VIH/VIL thresholds of the devices on that segment.
How do I reset the TCA9548A when the I2C bus hangs?
Pulse the RESET pin low for at least 6 ns (in practice, microseconds with an MCU GPIO). This performs a power-up-reset sequence: all channels disconnect, the control register clears, and the master-side bus is released. Tie RESET to a spare GPIO on every design — it is the cheapest watchdog you will ever add.
What pull-up resistors should I use on each channel?
Size them per segment: typically 2.2-10 kΩ depending on segment capacitance and bus speed. Because disabled channels are isolated, only the enabled channel and the master segment contribute capacitance, which is exactly why 400 kHz remains achievable on large systems.
How can I verify a TCA9548A is genuine and fully functional?
Scan the control register at 0x70-0x77, then enable one channel at a time and run an address scan on each downstream bus: channels must be mutually exclusive when only one is enabled. Counterfeit parts often crosstalk between channels. We functionally test isolation on sample lots.
What is the MOQ and lead time?
MOQ 1 reel (2,500 pcs TSSOP-24) or 25 pcs loose cut tape for prototyping. Shenzhen stock ships in 1-2 business days; TI authorized channel replenishment takes 6-12 weeks.
Alternatives & Equivalents
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