AN2014 datasheet(28/65 Pages) STMICROELECTRONICS

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Hardware considerations

AN2014

28/65

DocID10701 Rev 10

The decoupling capacitor (10 nF min) must be placed as close as possible to the

package pins VCC and VSS.

A pull-up resistor should be used only when the WC pin is driven by a Master I/O. If

unused, the WC pin must be connected to ground or left floating.

The I2C specification recommends to connect 220-Ohm serial resistors on SCL and

SDA. They are not useful unless identified overstress is liable to occur on these pins or

electromagnetic disturbances must be reduced.

Figure 21. Recommended I²C connections – safe design

1. The pull-up resistor values must be large enough so that the I²C-bus master can pull these lines low

(current sink capability of the I²C-bus master I/O's).

2. E0/E1/E2 must be connected either to VCC or to GND.

Figure 22. Recommended I²C connections – robust design

1. E0/E1/E2 must be connected either to VCC or to GND.

2. The use of external pull-up and pull-down resistors is strongly recommended even if the Master I/Os for the

I2C bus are already providing them. Please refer to Section 6.1.1 for more details.

AN2014 数据表(PDF) 28 Page - STMicroelectronics