DAC 芯片~ 16位超级好用,不容错过

The output voltage for any input code can be calculated asfollows:

D R1+R2 VO= VREF –VREF

65536R 1

R

2 (3) R1

where D represents the input code in decimal (0 to 65535).

With VREF = 5V, R1 = R2 = 10k :

10 D VO= –5V

65536

Due to the single ground pin of the DAC8501, all returncurrents, including digital and analog return currents, mustflow through the GND pin, which would, ideally, be con-nected directly to an analog ground plane. This plane wouldbe separate from the ground connection for the digital com-ponents until they were connected at the power-entry point ofthe system.

The power applied to VDD should be well regulated and lownoise. Switching power supplies and DC/DC converters willoften have high-frequency glitches or spikes riding on theoutput voltage. In addition, digital components can createsimilar high-frequency spikes as their internal logic switchesstates. This noise can easily couple into the DAC outputvoltage through various paths between the power connec-tions and analog output.

As with the GND connection, VDD should be connected to apower-supply plane or trace that is separate from the con-nection for digital logic until they are connected at the power-entry point. In addition, the 1µF to 10µF and 0.1µF bypasscapacitors are strongly recommended. In some situations,additional bypassing may be required, such as a 100µFelectrolytic capacitor or even a Pi filter made up of inductorsand capacitors—all designed to essentially low-pass filter the+5V supply, removing the high-frequency noise.

(4)

This is an output voltage range of ±5V with 0000H corre-sponding to a –5V output and FFFFH corresponding to a +5Voutput. Similarly, using VREF = 2.5V, a ±2.5V output voltagerange can be achieved.

LAYOUT

A precision analog component requires careful layout, ad-equate bypassing, and clean, well-regulated power supplies.As the DAC8501 offers single-supply operation, it will oftenbe used in close proximity with digital logic, microcontrollers,microprocessors, and digital signal processors. The moredigital logic present in the design and the higher the switch-ing speed, the more difficult it will be to keep digital noisefrom appearing at the output.

DAC8501

SBAS212A

15