1. General description
The PCA9522 is a monolithic bipolar integrated circuit for bus buffering in applications
including I
2
C-bus, SMBus, etc. It includes hot insertion logic for detecting stop and idle
conditions, making it ideal for live insertion into backplanes. The buffer extends the bus
load limit by buffering both the SCL and SDA lines. The PCA9522 is a drop-in
replacement for the IES5502, with only the maximum bus voltage reduced from 15 V to
10 V.
Hot insertion logic allows the IC to be plugged into live backplanes without causing data
corruption on the bus. The open-collector ready signal (RDY) indicates when the
connection has been made. Precharging of the backplane ports minimizes disruptions to
the bus during hot insertion.
The enable function allows sections of the bus to be isolated. Individual parts of the
system can be brought on-line successively. Bus level translation between a very wide
range of bus voltages, from 1.8 V to 10 V, is supported. These features provide enormous
flexibility in interfacing systems of different technologies, operating speeds and loads.
The unique operation of the PCA9522 provides one of the fastest response times of such
bidirectional buffers. It does this without the need for rise-time accelerators which,
combined with low noise margins, may cause glitches outside of the I
2
C-bus specification.
2. Features and benefits
Dual, bidirectional unity gain isolating buffer
Hot insertion logic prevents data and clock bus corruption for live backplane
applications
Pre-charge minimizes data corruption on live insertion
Supports I
2
C-bus (Standard-mode and Fast-mode), SMBus (standard and high power
modes) and PMBus
Open-collector ready output (RDY)
Fast switching times allow operation in excess of 1 MHz
Enable (EN) allows bus segments to be disconnected
Low current standby mode when not enabled
High-impedance ports when IC unpowered
6 mA (static) pull-down capability
Low noise susceptibility
Supports the connection of several buffers in series
Level shift bus voltages from 1.8 V to 10 V
PCA9522
Fast dual bidirectional bus buffer with hot insertion logic
Rev. 1 — 28 September 2011 Product data sheet
