Overview
The PCA9517D, produced by Texas Instruments, is a dual bidirectional I2C buffer designed for I2C bus and SMBus systems. This BiCMOS integrated circuit provides level shifting between low voltages (down to 0.9 V) and higher voltages (2.7 V to 5.5 V), enabling the extension of I2C bus systems without performance degradation during level shifting. It supports both Standard mode and Fast mode I2C devices, as well as multiple masters, and is compatible with mixed-mode signal operations.
Key Specifications
| Parameter | Conditions | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| VCCB supply voltage, B-side bus | 2.7 | 5.5 | V | ||
| VCCA supply voltage, A-side bus | 0.9 | 5.5 | V | ||
| ICC(VCCA) supply current on pin VCCA | 1 | mA | |||
| ICCH HIGH-state supply current both channels HIGH | VCC = 5.5 V; SDAn = SCLn = VCC | 1.5 | 5 | mA | |
| ICCL LOW-state supply current both channels LOW | VCC = 5.5 V; SDAn = SCLn = VCC | mA | |||
| tPLH LOW-to-HIGH propagation delay A-side to B-side | 25 | 53 | 110 | ns | |
| tPHL HIGH-to-LOW propagation delay A-side to B-side | 60 | 79 | 230 | ns | |
| tsu set-up time EN HIGH before START condition | 100 | ns | |||
| th hold time EN HIGH after STOP condition | 100 | ns |
Key Features
- I2C Bus and SMBus Compatibility: Supports both Standard mode and Fast mode I2C devices, as well as SMBus systems.
- Level Translation: Provides bidirectional voltage-level translation between low voltages (down to 0.9 V) and higher voltages (2.7 V to 5.5 V).
- Operating Supply Voltage Range: A-side operates from 0.9 V to 5.5 V, and B-side operates from 2.7 V to 5.5 V.
- Active-High Repeater-Enable Input: Allows the user to control when the repeater is active.
- Open-Drain I2C I/O: Supports open-drain configuration for the I2C bus.
- 5.5-V Tolerant I2C and Enable Input: Inputs and I/Os are overvoltage tolerant to 5.5 V, even when the device is unpowered.
- Lockup-Free Operation: Ensures reliable operation without lockups.
- Powered-Off High-Impedance I2C Pins: I2C pins are high-impedance when the device is unpowered.
- 400-kHz Fast I2C Bus: Supports up to 400 kHz clock frequency.
- ESD Protection: Exceeds 2000 V Human-Body Model (HBM) per JESD22-A114.
Applications
- Extension of I2C Bus Systems: Enables the connection of two buses with up to 400 pF bus capacitance each.
- Voltage and Capacitance Isolation: Isolates two halves of a bus for voltage and capacitance.
- Mixed-Mode Signal Operations: Supports mixed-mode signal operations, allowing level shifting between different voltage levels.
- Multi-Master Systems: Accommodates Standard mode and Fast mode I2C devices and multiple masters.
- Industrial and Automotive Systems: Suitable for use in various industrial and automotive applications requiring reliable I2C bus extension and level translation.
Q & A
- What is the PCA9517D used for?
The PCA9517D is used as a dual bidirectional I2C buffer for extending and level-translating I2C bus and SMBus systems.
- What are the operating voltage ranges for the A-side and B-side of the PCA9517D?
The A-side operates from 0.9 V to 5.5 V, and the B-side operates from 2.7 V to 5.5 V.
- Does the PCA9517D support clock stretching and arbitration across the repeater?
No, the PCA9517D does not support clock stretching and arbitration across the repeater.
- What is the maximum clock frequency supported by the PCA9517D?
The PCA9517D supports up to 400 kHz clock frequency.
- How does the PCA9517D handle overvoltage conditions?
All inputs and I/Os are overvoltage tolerant to 5.5 V, even when the device is unpowered.
- Can multiple PCA9517D devices be connected in series?
Yes, multiple PCA9517D devices can be connected in series (A-side to B-side) with no buildup in offset voltage.
- What is the purpose of the EN (enable) pin on the PCA9517D?
The EN pin allows the user to control when the repeater is active and can be used to isolate a badly behaved slave on power-up reset.
- How does the PCA9517D handle power-up conditions?
The PCA9517D includes a power-up circuit that keeps the output drivers turned off until VCCB is above 2.5 V and VCCA is above 0.8 V.
- What kind of ESD protection does the PCA9517D offer?
The PCA9517D offers ESD protection exceeding 2000 V Human-Body Model (HBM) per JESD22-A114.
- Can the PCA9517D be used in mixed-mode signal applications?
Yes, the PCA9517D supports mixed-mode signal operations, allowing level shifting between different voltage levels.
