Hot swappable I2C bus buffers
Philips Semiconductors has launched the new PCA951x family of I2C bus buffers. They are designed to help designers build bigger I2C systems for maintenance and control applications in CompactPCI (PICMG2.9) and AdvancedTCA (PICMG3.X) architectures.
The PCA951x family is the first in a series of hot swappable I2C bus buffers with enhanced features. Each member of the PCA951x family is similar in operation, containing specific features depending upon the application. The PCA9510/11/12/13/14 can also be used in normal I2C bus or SMBus applications, so that designers can add many more devices to a single bus than previously possible.
The CompactPCI (PICMG2.9) and AdvancedTCA architectures enable more extensive remote system management and configuration control of communication boards, power supplies and controllers. This significantly increases system reliability. Because I2C technology is well suited for system health maintenance and control buses, the hot swappable bus buffer family is ideal for use in all of today's advanced computing, communication and networking architectures.
The PCA951x devices communicate between system boards enabling insertion and removal of the boards into an active I2C system without corrupting the data on the I2C bus. The devices are designed to simplify the task of using a bus to manage a large number of boards in network server, desktop PC or telecom environments. For multiple system management buses, the devices can act as bus buffers with different voltages on each segment.
The PCA9511 is the most popular model, providing rise time accelerators to reduce rise time on heavily loaded buses. It also provides 1V precharge to reduce bus glitching, and an idle detect system that connects the new I2C devices to the active I2C bus only when the bus is idle to prevent damage to the system.
The PCA9510 removes the rise time accelerators for systems with multiple devices on a common bus or for lightly loaded systems. The PCA9512 has two VCC supplies for better noise margin in voltage translation applications and a hardware pin to disable the rise time accelerators.
The PCA9513/14 are variants of the PCA9511 with a higher rise time accelerator turn-on threshold to increase the noise margin in noisy applications. They have no precharge feature since the precharge is not required in some applications. The PCA9513 also features a 100A current source that replaces the conventional pull-up resistors required for the I2C bus. It also evens out the I2C bus RC time constant as boards are added or removed from the system.
19-Feb-2004