NXP Semiconductors PCA9509 Level Translating I2C-Bus/SMBus Repeater
NXP Semiconductors PCA9509 Level Translating I2C-Bus/SMBus Repeater provides two voltage supplies that enable the processor low voltage 2-wire serial bus to interface with the standard I2C-bus or SMBus I/O. While retaining all the operating modes and features of the I2C-bus system during the level shifts, The PCA9509 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 400pF on the higher voltage side. Port A allows a voltage range from 0.8V to 1.5V and requires no external pull-up resistors due to the internal current source. Port B allows a voltage range from 2.3V to 5.5V and is overvoltage tolerant. Both port A and port B SDA and SCL pins are high-impedance when the PCA9509A is unpowered.
The bus port B drivers of the PCA9509A are compliant with SMBus I/O levels, while port A uses an offset LOW which prevents bus lock-up and allows the bidirectional nature of the device. Port A uses a current source for pull-up and an offset 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 0.2VCC(A), while the input threshold of the internal buffer is set about 50mV 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 30% of SMBus or I2C-bus voltage level which enables port B to connect to any other I2C-bus devices or buffer.
The PCA9509A drivers are not enabled unless VCC(A) is above 0.7V and VCC(B) is above 1.7V. 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.
The PCA9509A is similar to the PCA9509 but offers lower A port voltage range to 0.8V to accommodate lower voltage processors and disables the current mirrors when disabled to reduce standby power.
The NXP Semiconductors PCA9509 Level Translating I2C-Bus/SMBus Repeater is offered in TSSOP8 and XQFN8 packages for design flexibility.
Features
- Bidirectional buffer isolates capacitance and allows 400pF on port B of the device
- Voltage level translation from port A (0.8V to 1.5V) to port B (2.3V to 5.5V)
- Requires no external pull-up resistors on lower voltage port A
- Active HIGH repeater enable input disables current mirrors and current source to reduce standby power
- Open-drain port B inputs/outputs
- Lock-up free operation
- Supports arbitration and clock stretching across the repeater
- Accommodates Standard-mode and Fast-mode I2C-bus devices and multiple masters
- Operating supply voltage range of 0.8V to 1.5V on port A, 2.3V to 5.5V on port B
- All pins are 5.0V tolerant with respect to ground pin
- 0Hz to 400kHz clock frequency
- ESD protection exceeds 2000V HBM per JESD22-A114 and 1000 V CDM per JESD22-C101
- Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100mA
- Packages options
- TSSOP8
- XQFN8
Applications
- White goods
- Dishwashers
- Washing machines
- Handheld devices
- Smartphones
- Tablets
- Digital cameras
- Data communications
- Routers
- Hubs
- Servers
Related Product
NXP Semiconductors PCA9617A Level Translating Fm+ I2C-Bus Repeater
Offers level shifting between low voltage and higher voltage Fast-mode Plus (Fm+) I2C-bus or SMBus.
NXP Semiconductors I2C General Purpose I/O Expanders
GPIO expansion for most microprocessor families, saving microprocessor GPIOs for critical functions.
Functional Diagram
