PCA9521DP: Fast dual bidirectional bus buffer

The PCA9521 is a monolithic bipolar integrated circuit for bus buffering in applications including I²C-bus, SMBus, PMBus, and other systems based on similar principles.

The buffer extends the bus load limit by buffering both the SCL and SDA lines. It supports up to 400 pF loads on each side of the buffer at 400 kHz. Higher capacitance is supported at lower speeds, and lower capacitance at higher speeds up to 1 MHz.

The enable function allows sections of the bus to be isolated. Individual parts of the system can be brought on-line successively. This means a controlled start-up using a diverse range of components, operating speeds and loads is easily achieved. Systems employing removable components on a back-plane (for example, telecommunications racks) can use the enable pin and the high-impedance ports on power-down to safely install and remove components in active systems.

Bus level translation between a very wide range of bus voltages, from 1.8 V to 10 V, is supported. This feature provides enormous flexibility in interfacing systems of different technologies.

The unique operation of the PCA9521 provides one of the fastest response times of such bidirectional buffers, ensuring any glitches (common to other buffers) are kept well within the 50 ns I²C-bus specification. Additionally, it does this without the need for ‘rise-time accelerators’ which, combined with low noise margins, may cause glitches outside of the I²C-bus specification.

Outline 3d SOT505-1
Data Sheets (1)
Name/DescriptionModified Date
Fast dual bidirectional bus buffer (REV 2.0) PDF (316.0 kB) PCA952119 Mar 2013
Users Guides (3)
Name/DescriptionModified Date
I2C-bus specification and user manual (REV 6.0) PDF (1.4 MB) UM1020428 Apr 2014
I2C-bus specification and user manual (REV 5.0) PDF (1.6 MB) UM10204_JA03 Apr 2013
I2C Demonstration Board 2005-1 Quick Start Guide (REV 1.0) PDF (261.0 kB) UM1020613 Jun 2006
Brochures (1)
Name/DescriptionModified Date
NXP® I2C-bus solutions 2014: Smart, simple solutions for the 12 most common design concerns (REV 1.0) PDF (3.5 MB) 7501754001 Aug 2014
Package Information (1)
Name/DescriptionModified Date
plastic thin shrink small outline package; 8 leads; body width 3 mm (REV 1.0) PDF (240.0 kB) SOT505-108 Feb 2016
Packing (1)
Name/DescriptionModified Date
TSSOP8; Reel pack; SMD, 13" Q1/T1 Standard product orientation Orderable part number ending ,118 or... (REV 1.0) PDF (214.0 kB) SOT505-1_11815 Apr 2013
Supporting Information (1)
Name/DescriptionModified Date
Reflow Soldering Profile (REV 1.0) PDF (34.0 kB) REFLOW_SOLDERING_PROFILE30 Sep 2013
Ordering Information
ProductStatusPackage versionApplicationEnableFunctionOperating Temperature (Cel)Number of bitsVoltage Translation Range (V)Operating voltage (VDC)Operating voltage 2 (V)InputsOutputsTTL Drive (mA)GTL Drive (mA)I2C-bus (kHz)
PCA9521DPEnd of LifeSOT505-1-40~852.7~5.5111000
Package Information
Product IDPackage DescriptionOutline VersionReflow/Wave SolderingPackingProduct StatusPart NumberOrdering code(12NC)MarkingChemical ContentRoHS / Pb Free / RHFLeadFree Conversion DateMSLMSL LF
PCA9521DPSOT505-1Reflow_Soldering_ProfileReel 13" Q1/T1WithdrawnPCA9521DP,118 (9352 924 34118)9521Always Pb-free11