I2C and SMBus Repeaters, Hubs, and Expanders Application Note
Design guide for using I2C/SMBus buffers, repeaters, and hubs to extend bus length, increase capacitance limits, and support hot-swapping and voltage level shifting.
Overview
This application note provides detailed technical information on NXP's family of I2C and SMBus interface components, including the PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B715, and P82B96. It addresses common design constraints such as exceeding the 400 pF maximum bus capacitance, long wiring for backplanes, and the need for voltage level translation between different logic supplies. The document explains device operations for multi-master environments, bus arbitration support, and bidirectional signaling without direction control. Design considerations covered include pull-up resistor calculation, maximum clock frequency for long cables, opto-electrical isolation, and hot-swap implementation with pin precharge and idle detect features.
Use Cases
- Expanding I2C bus capacitance beyond the 400 pF specification limit
- Implementing hot-swappable cards in active I2C backplanes
- Extending I2C/SMBus communication over long cables and across ground planes
- Level shifting between different I2C logic voltages (e.g., 3.3V to 5V)
- Creating star-configuration I2C networks using multi-channel hubs
- Providing opto-isolation for I2C signals in high-noise or high-voltage environments
Topics
Referenced Parts
GTL2000
NXP Semiconductors
The GTL2000/02/10 allow I2C voltage level translation at any voltage between 1.0 V and 5.0 V.
GTL2002
NXP Semiconductors
The GTL2000/02/10 allow I2C voltage level translation at any voltage between 1.0 V and 5.0 V.
GTL2010
NXP Semiconductors
The GTL2000/02/10 allow I2C voltage level translation at any voltage between 1.0 V and 5.0 V.
P82B715
NXP Semiconductors
PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715
P82B715PN
NXP Semiconductors
P82B715PN P82B96PN
P82B715TD
NXP Semiconductors
PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD
P82B96
NXP Semiconductors
PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715
P82B96DP
NXP Semiconductors
P82B96DP
P82B96PN
NXP Semiconductors
P82B715PN P82B96PN
P82B96TD
NXP Semiconductors
PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD
PCA9511
NXP Semiconductors
PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715
PCA9511D
NXP Semiconductors
PCA9511D PCA9512D PCA9513D PCA9514D
PCA9511DP
NXP Semiconductors
PCA9511DP-T PCA9512DP-T PCA9513DP-T PCA9514DP-T
PCA9512
NXP Semiconductors
PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715
PCA9512D
NXP Semiconductors
PCA9511D PCA9512D PCA9513D PCA9514D
PCA9512DP
NXP Semiconductors
PCA9511DP-T PCA9512DP-T PCA9513DP-T PCA9514DP-T
PCA9513
NXP Semiconductors
PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715
PCA9513D
NXP Semiconductors
PCA9511D PCA9512D PCA9513D PCA9514D
PCA9513DP
NXP Semiconductors
PCA9511DP-T PCA9512DP-T PCA9513DP-T PCA9514DP-T
PCA9514
NXP Semiconductors
PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715
PCA9514D
NXP Semiconductors
PCA9511D PCA9512D PCA9513D PCA9514D
PCA9514DP
NXP Semiconductors
PCA9511DP-T PCA9512DP-T PCA9513DP-T PCA9514DP-T
PCA9515
NXP Semiconductors
PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715
PCA9515D
NXP Semiconductors
PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD
PCA9515DP
NXP Semiconductors
PCA9515DP-T
PCA9516
NXP Semiconductors
PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715
PCA9516D
NXP Semiconductors
PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD
PCA9516PW
NXP Semiconductors
PCA9516PW PCA9518PW
PCA9518
NXP Semiconductors
PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715
PCA9518D
NXP Semiconductors
PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD
PCA9518PW
NXP Semiconductors
PCA9516PW PCA9518PW
| LTC1694 | Analog Devices | APPENDIX 6 - Differences Between the LTC1694 and LTC1694-1 |
| LTC1694-1 | Analog Devices | APPENDIX 6 - Differences Between the LTC1694 and LTC1694-1 |
| GTL2000 | NXP Semiconductors | The GTL2000/02/10 allow I2C voltage level translation at any voltage between 1.0 V and 5.0 V. |
| GTL2002 | NXP Semiconductors | The GTL2000/02/10 allow I2C voltage level translation at any voltage between 1.0 V and 5.0 V. |
| GTL2010 | NXP Semiconductors | The GTL2000/02/10 allow I2C voltage level translation at any voltage between 1.0 V and 5.0 V. |
| P82B715 | NXP Semiconductors | PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715 |
| P82B715PN | NXP Semiconductors | P82B715PN P82B96PN |
| P82B715TD | NXP Semiconductors | PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD |
| P82B96 | NXP Semiconductors | PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715 |
| P82B96DP | NXP Semiconductors | P82B96DP |
| P82B96PN | NXP Semiconductors | P82B715PN P82B96PN |
| P82B96TD | NXP Semiconductors | PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD |
| PCA9511 | NXP Semiconductors | PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715 |
| PCA9511D | NXP Semiconductors | PCA9511D PCA9512D PCA9513D PCA9514D |
| PCA9511DP | NXP Semiconductors | PCA9511DP-T PCA9512DP-T PCA9513DP-T PCA9514DP-T |
| PCA9512 | NXP Semiconductors | PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715 |
| PCA9512D | NXP Semiconductors | PCA9511D PCA9512D PCA9513D PCA9514D |
| PCA9512DP | NXP Semiconductors | PCA9511DP-T PCA9512DP-T PCA9513DP-T PCA9514DP-T |
| PCA9513 | NXP Semiconductors | PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715 |
| PCA9513D | NXP Semiconductors | PCA9511D PCA9512D PCA9513D PCA9514D |
| PCA9513DP | NXP Semiconductors | PCA9511DP-T PCA9512DP-T PCA9513DP-T PCA9514DP-T |
| PCA9514 | NXP Semiconductors | PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715 |
| PCA9514D | NXP Semiconductors | PCA9511D PCA9512D PCA9513D PCA9514D |
| PCA9514DP | NXP Semiconductors | PCA9511DP-T PCA9512DP-T PCA9513DP-T PCA9514DP-T |
| PCA9515 | NXP Semiconductors | PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715 |
| PCA9515D | NXP Semiconductors | PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD |
| PCA9515DP | NXP Semiconductors | PCA9515DP-T |
| PCA9516 | NXP Semiconductors | PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715 |
| PCA9516D | NXP Semiconductors | PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD |
| PCA9516PW | NXP Semiconductors | PCA9516PW PCA9518PW |
| PCA9518 | NXP Semiconductors | PCA9511, PCA9512, PCA9513, PCA9514, PCA9515, PCA9516, PCA9518, P82B96, P82B715 |
| PCA9518D | NXP Semiconductors | PCA9515D PCA9516D PCA9518D P82B715TD P82B96TD |
| PCA9518PW | NXP Semiconductors | PCA9516PW PCA9518PW |