PCA9555A 查看數據表（PDF） - NXP Semiconductors.

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PCA9555A

Low-voltage 16-bit I2C-bus I/O port with interrupt and weak pull-up

NXP Semiconductors. 

NXP Semiconductors

PCA9555A

Low-voltage 16-bit I2C-bus I/O port with interrupt and weak pull-up

8.3 Device current consumption with internal pull-up and pull-down

resistors

The PCA9555A integrates pull-up resistors to eliminate external components when pins

are configured as inputs and pull-up resistors are required (for example, nothing is driving

the inputs to the power supply rails. Since these pull-up resistors are internal to the device

itself, they contribute to the current consumption of the device and must be considered in

the overall system design.

If the resistor is configured as a pull-up, that is, connected to VDD, a current will flow from

the VDD pin through the resistor to ground when the pin is held LOW. This current will

appear as additional IDD upsetting any current consumption measurements.

The pull-up resistors are simple resistors and the current is linear with voltage. The

resistance specification for these devices spans from 50 k with a nominal 100 k value.

Any current flow through these resistors is additive by the number of pins held LOW and

the current can be calculated by Ohm’s law. See Figure 22 for a graph of supply current

versus the number of pull-up resistors.

PCA9555A

Product data sheet

All information provided in this document is subject to legal disclaimers.

Rev. 1 — 11 September 2012

© NXP B.V. 2012. All rights reserved.

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