P82B715 Status: ACTIVE

Product Information

Features

• Operating Power-Supply Voltage Range of 3 V to 12 V
• Supports Bidirectional Data Transfer of I²C Bus Signals
• Allows Bus Capacitance of 400 pF on Main I²C Bus (Sx/Sy Side) and 3000 pF on Transmission Side (Lx/Ly Side)
• Dual Bidirectional Unity-Voltage-Gain Buffer With No External Directional Control Required
• Drives 10× Lower-Impedance Bus Wiring for Improved Noise Immunity
• Multi-Drop Distribution of I²C Signals Using Low-Cost Twisted-Pair Cables
• I²C Bus Operation Over 50 Meters of Twisted-Pair Wire
• Latch-up Performance Exceeds 100 mA Per JESD 78, Class II
• ESD Protection Exceeds JESD 22
  • 2500-V Human-Body Model (A114-A)
  • 400-V Machine Model (A115-A)
  • 1000-V Charged-Device Model (C101)

DESCRIPTION/ORDERING INFORMATION

The P82B715 is a bipolar device intended for I²C bus systems applications and supports bidirectional data transfer via the I²C bus. The P82B715 buffers both the serial data (SDA) and serial clock (SCL) signals on the I²C bus and allows for extension of the I²C bus, while retaining all the operating modes and features of the I²C system.

In general, the I²C bus capacitance limit of 400 pF restricts practical communication distances to a few meters. One of the advantages of the P82B715 is that it can isolate bus capacitance such that the total loading (devices, connectors, traces and wires) of the new bus or remote I²C nodes are not apparent to other I²C buses (or nodes). This is achieved by using one P82B715 device at each end of a long cable. The pin Lx of one P82B715 device has to be connected to Lx of the second P82B715 (similarly for Ly). This allows the total system capacitance load to be around 3000 pF. The P82B715 uses unidirectional analog current amplification to increase the current sink capability of I²C chips by a factor of ten and to change the 400-pF I²C bus specification limit into a 4-nF bus wiring capacitance limit. That means longer cables or lower-cost general-purpose wiring may be used to connect two separate I²C-based systems, without worrying about the special voltage levels associated with other I²C bus buffers.

Multiple P82B715s can be connected together in a star or multipoint architecture by their Lx/Ly ports, without limit, as long as the total capacitance of the system remains less than about 3000 pF (400 pF or less when referenced to any Sx/Sy connection). In that arrangement, the master and/or slave devices are attached to the Sx/Sy port of each P82B715. The P82B715 alone does not support voltage-level translation, but it simplifies the application of low-cost transistors for this purpose. In normal use, the power-supply voltages at each end of the low-impedance buffered bus line should be the same. If these differ by a significant amount, noise margin is sacrificed.

Two or more Sx or Sy I/Os can be interconnected and are also fully compatible with bus buffers that use voltage-level offsets (such as the PCA9515A) because it duplicates and transmits the offset voltage.