Datasheet

www.ti.com
USING REF02 AS A POWER SUPPLY FOR DAC8574
REF02
15 V
5 V
950 A
V
DD
, V
ref
SCL
SDA
I
2
C
Interface
V
OUT
= 0 V to 5 V
DAC8574
DAC8574
SLAS377B – JANUARY 2003 – REVISED DECEMBER 2004
APPLICATION INFORMATION (continued)
Due to the extremely low supply current required by the DAC8574, a possible configuration is to use a REF02
+5 V precision voltage reference to supply the required voltage to the DAC8574's supply input as well as the
reference input, as shown in Figure 58 . This is especially useful if the power supply is quite noisy or if the system
supply voltages are at some value other than 5 V. The REF02 outputs a steady supply voltage for the DAC8574.
If the REF02 is used, the current it needs to supply to the DAC8574 is 950 µA typical and 1600 µA max for V
DD
= 5 V. When a DAC output is loaded, the REF02 also needs to supply the current to the load. The total typical
current required (with a 5-k Ω load on a single DAC output) is:
950 µA + (5 V / 5 k Ω) = 1.950 mA
The load regulation of the REF02 is typically 0.005%/mA, which results in an error of 488 µV for 1.950-mA of
current drawn from it. This corresponds to a 6.4 LSB error for a 0-V to 5-V output range.
Figure 58. REF02 Power Supply
REF3040 can also be used to generate a 4.096-V reference from a 5-V supply.
31