TCA9509

• Two-Channel Bidirectional Buffer
• I²C Bus and SMBus Compatible
• Operating Supply Voltage Range of
  2.7 V to 5.5 V on B side
• Operating Voltage Range of 0.9 V to 5.5 V on
  A-Side
• Voltage-Level Translation From
  0.9 V to 5.5 V and 2.7 V to 5.5 V
• Active-High Repeater-Enable Input
• Requires No External Pullup Resistors on
  Lower-Voltage Port-A
• Open-Drain I²C I/O
• 5.5-V Tolerant I²C and Enable Input Support Mixed-Mode Signal Operation
• Lockup-Free Operation
• Accommodates Standard Mode and Fast Mode I²C Devices and Multiple Masters
• Supports Arbitration and Clock Stretching Across Repeater
• Powered-Off High-Impedance I²C Bus Pins
• Supports 400-kHz Fast I²C Bus Operating Speeds
• Available in
  • 1.6-mm × 1.6-mm, 0.4-mm height, 0.5-mm Pitch QFN Package
  • 3-mm × 3-mm Industry Standard MSOP Package
• Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II
• ESD Protection Exceeds JESD 22
  • 2000-V Human-Body Model (A114-A)
  • 1000-V Charged-Device Model (C101)

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This TCA9509 integrated circuit is an I²C bus/SMBus Repeater for use in I²C/SMBus systems. It can also provide bidirectional voltage-level translation (up-translation/down-translation) between low voltages (down to 0.9 V) and higher voltages (2.7 V to 5.5 V) in mixed-mode applications. This device enables I²C and similar bus systems to be extended, without degradation of performance even during level shifting.

The TCA9509 buffers both the serial data (SDA) and the serial clock (SCL) signals on the I²C bus, thus allowing 400-pF bus capacitance on the B-side. This device can also be used to isolate two halves of a bus for voltage and capacitance.

The TCA9509 has two types of drivers – A-side drivers and B-side drivers. All inputs and B-side I/Os are overvoltage tolerant to 5.5 V. The A-side I/Os are overvoltage tolerant to 5.5 V when the device is unpowered (VCCB and/or VCCA = 0 V).

The bus port B drivers are compliant with SMBus I/O levels, while the A-side uses a current sensing mechanism to detect the input or output LOW signal which prevents bus lock-up. The A-side uses a 1 mA current source for pull-up and a 200 Ω pull-down driver. This results in a LOW on the A-side accommodating smaller voltage swings. The output pull-down on the A-side 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 A-side 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 B-side drives a hard LOW and the input level is set at 0.3 of SMBus or I²C-bus voltage level which enables B side to connect to any other I²C-bus devices or buffer.

The TCA9509 drivers are not enabled unless V_CCA is above 0.8 V and V_CCB is above 2.5 V. 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.