DAC8574IPW.B datasheet(29/46 Pages) TI2

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DAC8574

VOUTA

VOUTB

VREFH

VDD

VREFL

GND

VOUTC

VOUTD

IOVDD

SDA

SCL

LDAC

SDA

SCL

I2C Pullup Resistors

1 k

Ω to 10 kΩ (typical)

IOVDD

Microcontroller or

Microprocessor With

I2C Port

NOTE: DAC8574 power and input/output connections are omitted for clarity, except I2C Inputs.

USING GPIO PORTS FOR I

DAC8574

SLAS377B – JANUARY 2003 – REVISED DECEMBER 2004

APPLICATION INFORMATION (continued)

Figure 56. Typical DAC8574 Connections

The DAC8574 interfaces directly to standard mode, fast mode and high-speed mode I

2C controllers. Any

microcontroller's I

2C peripheral, including master-only and non-multiple-master I2C peripherals, work with the

DAC8574. The DAC8574 does not perform clock-stretching (i.e., it never pulls the clock line low), so it is not

necessary to provide for this unless other devices are on the same I

2C bus.

Pullup resistors are necessary on both the SDA and SCL lines because I

2C bus drivers are open-drain. The size

of the these resistors depend on the bus operating speed and capacitance on the bus lines. Higher-value

resistors consume less power, but increase the transition times on the bus, limiting the bus speed. Lower-value

resistors allow higher speed at the expense of higher power consumption. Long bus lines have higher

capacitance and require smaller pullup resistors to compensate. If the pullup resistors are too small the bus

drivers may not be able to pull the bus line low.

Most microcontrollers have programmable input/output pins that can be set in software to act as inputs or

outputs. If an I

2C controller is not available, the DAC8574 can be connected to GPIO pins, and the I2C bus

protocol simulated, or bit-banged, in software. An example of this for a single DAC8574 is shown in Figure 57.

DAC8574IPW.B Datasheet(PDF) 29 Page - Texas Instruments

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