DAC8574 Datasheet, PDF (29/40 Pages) Texas Instruments – QUAD, 16-BIT, LOW-POWER, VOLTAGE OUTPUT, I2C INTERFACE DIGITAL-TO-ANALOG CONVERTER

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DAC8574
SLAS377A – JANUARY 2003 – REVISED JUNE 2003
APPLICATION INFORMATION
The following sections give example circuits and tips for using the DAC8574 in various applications. For more
information, contact your local TI representative, or visit the Texas Instruments website at http://www.ti.com.
BASIC CONNNECTIONS
For many applications, connecting the DAC8574 is extremely simple. A basic connection diagram for the
DAC8574 is shown in Figure 56. The 0.1 µF bypass capacitors help provide the momentary bursts of extra
current needed from the supplies.
I²C Pullup Resistors ^IOVDD
1 kΩ to 10 kΩ (typical)
Microcontroller or
Microprocessor With
I²C Port
DAC8574
1 VOUTA
A3 16
2 VOUTB
A2 15
3 V_REFH
4 V_DD
A1 14
A0 13
5 V_REFL IOV_DD 12
6 GND
SDA 11
7 V_{OUTC SCL} 10
8 V_OUTD L_DAC 9
SCL
SDA
NOTE: DAC8574 power and input/output connections are omitted for clarity, except I²C Inputs.
Figure 56. Typical DAC8574 Connections
The DAC8574 interfaces directly to standard mode, fast mode and high-speed mode I²C controllers. Any
microcontroller’s I²C 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 I²C bus.
Pullup resistors are necessary on both the SDA and SCL lines because I²C 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.
USING GPIO PORTS FOR I²C
Most microcontrollers have programmable input/output pins that can be set in software to act as inputs or
outputs. If an I²C 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.
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