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PCA9509

NXP
Part Number PCA9509
Manufacturer NXP
Description Level translating I2C-bus/SMBus repeater
Published Jan 19, 2007
Detailed Description PCA9509 Level translating I2C-bus/SMBus repeater Rev. 7 — 4 November 2014 Product data sheet 1. General description Th...
Datasheet PDF File PCA9509 PDF File

PCA9509
PCA9509

Overview
PCA9509 Level translating I2C-bus/SMBus repeater Rev.
7 — 4 November 2014 Product data sheet 1.
General description The PCA9509 is a level translating I2C-bus/SMBus repeater that enables processor low voltage 2-wire serial bus to interface with standard I2C-bus or SMBus I/O.
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, thus enabling the I2C-bus or SMBus maximum capacitance of 400 pF on the higher voltage side.
Port A allows a voltage range from 1.
35 V to VCC(B)  1.
0 V and requires no external pull-up resistors due to the internal current source.
Port B allows a voltage range from 3.
0 V to 5.
5 V and is overvoltage tolerant.
Both port A and port B SDA and SCL pins are high-impedance when the PCA9509 is unpowered.
For applications where Port A VCC(A) is less than 1.
35 V or Port B VCC(B) is less than 3.
0 V, use drop-in replacement PCA9509A.
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 200  pull-down driver.
This results 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.
2 V, 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 PCA9509 drivers are not enabled unless VCC(A) is above 0.
8 V and VCC(B) is above 2.
5 V.
The enable ...


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