Product details


Features Buffer Frequency (Max) (kHz) 400 VCCA (Min) (V) 2.3 VCCA (Max) (V) 3.6 VCCB (Min) (V) 2.3 VCCB (Max) (V) 3.6 Supply restrictions VCC Single Supply Rating Catalog Operating temperature range (C) -40 to 85 open-in-new Find other I2C level shifters, buffers & hubs


  • Two-Channel Bidirectional Buffers
  • I2C Bus and SMBus Compatible
  • Active-High Repeater-Enable Input
  • Open-Drain I2C I/O
  • 5.5-V Tolerant I2C I/O and Enable Input Support Mixed-Mode Signal Operation
  • Lockup-Free Operation
  • Accommodates Standard Mode and Fast Mode I2C Devices and Multiple Masters
  • Powered-Off High-Impedance I2C Pins
  • Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II
  • ESD Protection Exceeds JESD 22
    • 2000-V Human-Body Model (A114-A)
    • 200-V Machine Model (A115-A)
    • 1000-V Charged-Device Model (C101)

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This dual bidirectional I2C buffer is operational at 2.3-V to 3.6-V VCC.

The PCA9515A is a BiCMOS integrated circuit intended for I2C bus and SMBus systems applications. The device contains two identical bidirectional open-drain buffer circuits that enable I2C and similar bus systems to be extended without degradation of system performance.

The PCA9515A buffers both the serial data (SDA) and serial clock (SCL) signals on the I2C bus, while retaining all the operating modes and features of the I2C system. This enables two buses of 400-pF bus capacitance to be connected in an I2C application.

The I2C bus capacitance limit of 400 pF restricts the number of devices and bus length. Using the PCA9515A enables the system designer to isolate two halves of a bus, accommodating more I2C devices or longer trace lengths.

The PCA9515A has an active-high enable (EN) input with an internal pullup, which allows the user to select when the repeater is active. This can be used to isolate a badly behaved slave on power-up reset. It never should change state during an I2C operation, because disabling during a bus operation hangs the bus, and enabling part way through a bus cycle could confuse the I2C parts being enabled. The EN input should change state only when the global bus and the repeater port are in an idle state, to prevent system failures.

The PCA9515A also can be used to run two buses: one at 5-V interface levels and the other at 3.3-V interface levels, or one at 400-kHz operating frequency and the other at 100-kHz operating frequency. If the two buses are operating at different frequencies, the 100-kHz bus must be isolated when the 400-kHz operation of the other bus is required. If the master is running at 400 kHz, the maximum system operating frequency may be less than 400 kHz, because of the delays that are added by the repeater.

The PCA9515A does not support clock stretching across the repeater.

The output low levels for each internal buffer are approximately 0.5 V, but the input voltage of each internal buffer must be 70 mV or more below the output low level, when the output internally is driven low. This prevents a lockup condition from occurring when the input low condition is released.

Two or more PCA9515A devices cannot be used in series. The PCA9515A design does not allow this configuration. Because there is no direction pin, slightly different valid low-voltage levels are used to avoid lockup conditions between the input and the output of each repeater. A valid low applied at the input of a PCA9515A is propagated as a buffered low with a slightly higher value on the enabled outputs. When this buffered low is applied to another PCA9515A-type device in series, the second device does not recognize it as a valid low and does not propagate it as a buffered low again.

The device contains a power-up control circuit that sets an internal latch to prevent the output circuits from becoming active until VCC is at a valid level (VCC = 2.3 V).

As with the standard I2C system, pullup resistors are required to provide the logic high levels on the buffered bus. The PCA9515A has standard open-collector configuration of the I2C bus. The size of these pullup resistors depends on the system, but each side of the repeater must have a pullup resistor. The device is designed to work with Standard Mode and Fast Mode I2C devices in addition to SMBus devices. Standard Mode I2C devices only specify 3 mA in a generic I2C system where Standard Mode devices and multiple masters are possible. Under certain conditions, high termination currents can be used.

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Exact equivalent in functionality and parametrics to the compared device:
PCA9515B ACTIVE 2-bit bidirectional 2.3- to 3.6-V 400-kHz I2C/SMBus buffer It addresses the application usage limitations as specified in the PCA9515A datasheet

Technical documentation

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Type Title Date
* Datasheet PCA9515A Dual Bidirectional I2C Bus and SMBus Repeater datasheet (Rev. D) Jun. 12, 2014
Application note Why, When, and How to use I2C Buffers May 23, 2018
Selection guide Logic Guide (Rev. AB) Jun. 12, 2017
Application note Choosing the Correct I2C Device for New Designs Sep. 07, 2016
Application note Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) Dec. 02, 2015
Application note Understanding the I2C Bus Jun. 30, 2015
Application note Maximum Clock Frequency of I2C Bus Using Repeaters May 15, 2015
Application note I2C Bus Pull-Up Resistor Calculation Feb. 13, 2015
Application note Troubleshooting I2C Bus Protocol Oct. 19, 2009
Application note Programming Fun Lights With TI's TCA6507 Nov. 30, 2007
Application note Semiconductor Packing Material Electrostatic Discharge (ESD) Protection Jul. 08, 2004

Design & development

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Design tools & simulation

SCEJ213.ZIP (216 KB) - HSpice Model
PSpice® for TI design and simulation tool
PSPICE-FOR-TI — PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
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SPICE-based analog simulation program
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I2C designer tool
I2C-DESIGNER — Use the I2C Designer tool to quickly resolve conflicts in addressing, voltage level and frequency in I2C based designs. Enter master and slave inputs to automatically generate an I2C tree or easily build a custom solution. This tool will help designers save time and comply with the I2C standard with (...)
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Reference designs

Accurate Temperature, Light Sensing, and Diagnostics Reference Design for Smart Grid Applications
TIDA-00811 — This reference design provides accurate measurements of ambient light intensity used to detect arc flash faults with a fast response of 1 ms, protecting or minimizing damages to power distribution switchgear. This design also monitors temperature (using switch, analog, digital or remote ), humidity (...)
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