SCPU045 June   2021 TCA39306

 

  1.   Trademarks
  2. 1Introduction
  3. 2Concept
    1. 2.1 EVM Features
    2. 2.2 Adjustable pull-up resistors
    3. 2.3 Load Capacitance Selector
    4. 2.4 DUT locations
  4. 3Schematic
  5. 4Bill of Material
  6. 5Layout
  7. 6Revision History

2.2 Adjustable pull-up resistors

TCA39306EVM comes with adjustable pull-up resistors which allows for the user to select from a 4.7 k and 820 Ω resistor. The board itself has a 10 k pull-up resistor on the I2C bus when no resistors are selected from the adjustable pull up bank. When 4.7 k is selected, the effective pull up resistance is 3.2 kΩ. When only the 820 Ω pull-up is selected, the effective pull up resistance is about 750 Ω. When both adjustable pull-up resistors are selected the effective resistance is about 650 Ω. The pull-up resistor selectors are shown in Figure 2-1.

Table 2-1 Effective pull-up resistor values table
Pull-up resistor (Ω)Equivalent pull-up resistance (Ω)
10k || 4.7 k3.2 k
10k || 820~750
10k || 4.7 k || 820~650
GUID-20210526-CA0I-TSPV-SHMG-97NZHGB5Q3LQ-low.pngFigure 2-1 Adjustable pull-up resistors