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The PI6ULS5V9509 is a level translating I2Cbus/SMBus repeater. It can provide bidirectional level translation between low voltage (down to 1.1V) and higher voltage (2.5V to 5.5V) in mixed-mode applications. And it enables I2C and similar bus system to be extended, without degradation of performance even during level shifting.
The PI6ULS5V9509 enables the system designer to isolate two halves of a bus for both voltage and capacitance, accommodating more I2C devices or longer trace length. It also permits extension of the I2C-bus by providing bidirectional buffering for both the data (SDA) and the clock (SCL) lines, thus allowing two buses of 400 pF to be connected in an I2C application.
The bus port B drivers are compliant with SMBus I/O levels, while port A uses a current sensing mechanism to detect the input or output LOW signal which prevents bus lock-up. Port A uses a 1 mA current source for pull-up and a 200Ω pull-down driver. This result in a LOW on the port A accommodating smaller voltage swings. The output pull-down on the port A internal buffer LOW is set for approximately 0.2V, while the input threshold of the internal buffer is set about 50 mV lower than that of the output voltage LOW. When the port A I/O is driven LOW internally, the LOW is not recognized as a LOW by the input. This prevents a lock-up condition from occurring. The output pull-down on the port B drives a hard LOW and the input level is set at 0.3 of SMBus or I2C-bus voltage level which enables port B to connect to any other I2C-bus devices or buffer.
The PI6ULS5V9509 drivers are not enabled unless VCC(A) is above 0.8 V and VCC(B) is above 2.5 V. The enable (EN) pin can also be used to turn the drivers on and off under system control. Caution should be observed to only change the state of the EN pin when the bus is idle.
Bidirectional buffer isolates capacitance and allows 400 pF on port B of the device
Port A operating supply voltage range of 1.1 V to VCC(B) - 1.0V
Port B operating supply voltage range of 2.5 V to 5.5 V
Voltage level translation from 1.1V to VCC(B) - 1.0V and from 2.5 V to 5.5 V
Requires no external pull-up resistors on lower voltage port A
Open-drain port B inputs/outputs
Lock-up free operation
Supports arbitration and clock stretching across the repeater
Accommodates Standard-mode and Fast-mode I2Cbus devices and multiple masters
Powered-off high-impedance I2C-bus pins
5 V tolerant B SCL, SDA and enable pins
0 Hz to 400 kHz clock frequency (Remark: The maximum system operating frequency may be less than 400 kHz because of the delays added by the repeater.)