I2C voltage level translation for DDR4 at speeds up to 1 MHz

August 07, 2013 // By Graham Prophet
A bidirectional voltage I2C-bus translation buffer is intended for application in areas such as high-performance servers.

The PCA9617A Fast-mode Plus (Fm+) I²C-bus buffer from NXP is designed for emerging server applications that use DDR4 SDRAM memory. This breakthrough voltage-translating bus buffer allows engineers to design next-generation server systems using new DDR4 technology with the I²C-bus operating at up to 1 MHz, and voltage level translation of 0.8V on the CPU side to 2.5V on the SDRAM module side. NXP continues to drive innovation on the I²C-bus; the PCA9617A is the first Fm+ device specifically designed for servers. It operates up to 1 MHz with normal Fast-mode drive to allow operation on more heavily capacitive loaded buses, but is backward-compatible to Fast-mode and Standard-mode speeds.

The PCA9617A is a CMOS integrated circuit that provides voltage level shifting between 0.8V and 2.5V supply voltages for Fast-mode plus I²C-bus or SMBus applications. While retaining all the operating modes and features of the I²C-bus system during the level shifts, it also permits extension of the I²C-bus by providing bidirectional buffering for both the data (SDA) and the clock (SCL) lines, one bus, split into two sections of 550 pF (max) at 1 MHz. Using the PCA9617A enables the system designer to buffer the load capacitance of the bus, and provide voltage level translation. The SDA and SCL pins are overvoltage tolerant and are high impedance when the PCA9617A is unpowered. Evaluation samples and demo boards are available immediately. The PCA9617A is available in TSSOP8 (MSOP8) “DP” and smaller leadless HWSON8 “TP” packages.


“Our primary server architecture customers asked us to develop an improved version of the PCA9517A that was faster and supported lower voltages for their next-generation architecture. Working closely with them, we released the PCA9617A to allow their engineers to meet the complex specifications of their advanced server architectures,” said Stephen Blozis, international product marketing manager, NXP Semiconductors. “NXP will continue to develop innovative ways in which the I²C-bus can be used in advanced systems and enable engineers