Overview
The PCA9512AD,112 is a hot swappable I2C-bus and SMBus buffer produced by NXP USA Inc. This component is designed to facilitate the insertion of I/O cards into a live backplane without corrupting the data and clock buses. It features level shifting capabilities, allowing it to operate between 3.3 V and 5 V systems, and includes dedicated supply voltage pins to maintain the best noise margin for each voltage level.
Key Specifications
| Parameter | Description |
|---|---|
| Supply Voltage Range | 2.7 V to 5.5 V |
| Operating Modes | I2C-bus Standard mode, I2C-bus Fast mode, and SMBus standards |
| Level Shifting | Between 3.3 V and 5 V systems |
| Pins | Includes SDAIN, SDAOUT, SCLIN, SCLOUT, VCC, VCC2, GND, and ACC pins |
| Rise Time Accelerator | Allows the use of weaker DC pull-up currents while meeting rise time requirements |
| Precharge Circuitry | SDAn and SCLn pins precharged to 1 V during insertion to minimize current required |
| Undervoltage Lockout | Disabled until both VCC and VCC2 are above 2.5 V |
Key Features
- Bidirectional buffer for SDA and SCL lines to increase fan-out and prevent corruption during live board insertion and removal.
- Compatible with I2C-bus Standard mode, I2C-bus Fast mode, and SMBus standards.
- Level shifting between 3.3 V and 5 V systems with dedicated supply voltage pins.
- Rise time accelerator circuitry to meet rise time requirements with weaker DC pull-up currents.
- Digital input pin (ACC) to enable or disable rise time accelerators.
- Precharge circuitry to minimize current required during insertion by precharging SDAn and SCLn pins to 1 V.
Applications
- Multipoint backplane systems where hot swappable I/O cards are used.
- Systems requiring level shifting between different voltage levels (3.3 V and 5 V).
- Applications needing bidirectional buffering to prevent data and clock bus corruption.
- Industrial and automotive systems where reliable and robust I2C/SMBus communication is crucial.
Q & A
- What is the primary function of the PCA9512AD,112?
The PCA9512AD,112 is a hot swappable I2C-bus and SMBus buffer that allows I/O card insertion into a live backplane without corrupting the data and clock buses.
- What are the supported operating modes of the PCA9512AD,112?
The component supports I2C-bus Standard mode, I2C-bus Fast mode, and SMBus standards.
- What is the supply voltage range for the PCA9512AD,112?
The supply voltage range is from 2.7 V to 5.5 V.
- How does the PCA9512AD,112 handle level shifting between different voltage systems?
The component includes dedicated supply voltage pins to provide level shifting between 3.3 V and 5 V systems while maintaining the best noise margin for each voltage level.
- What is the purpose of the rise time accelerator circuitry in the PCA9512AD,112?
The rise time accelerator circuitry allows the use of weaker DC pull-up currents while still meeting the rise time requirements.
- How does the PCA9512AD,112 minimize current during I/O card insertion?
The SDAn and SCLn pins are precharged to 1 V during insertion to minimize the current required to charge the parasitic capacitance of the chip.
- What happens if either VCC or VCC2 drops below 2.0 V in the PCA9512AD,112?
If either VCC or VCC2 drops below 2.0 V, the component returns to the undervoltage lockout state, disabling the connection circuitry, rise time accelerators, and precharge circuitry.
- What is the role of the ACC pin in the PCA9512AD,112?
The ACC pin is a CMOS threshold digital input that enables or disables the rise time accelerators on all four SDAn and SCLn pins.
- In what types of systems is the PCA9512AD,112 typically used?
The component is typically used in multipoint backplane systems, industrial systems, and automotive systems where hot swappable I/O cards and reliable I2C/SMBus communication are necessary.
- How does the PCA9512AD,112 prevent bus contention during card insertion?
The component prevents the backplane from being connected to the card until a stop bit or bus idle occurs on the backplane, thus avoiding bus contention on the card.
