DAC8501_芯片手册(11)

DAC 芯片~ 16位超级好用,不容错过

TYPICAL CHARACTERISTICS: VDD = +2.7V (Cont.)

At TA = +25°C, and +VDD = +2.7V, unless otherwise noted.

CODE CHANGE GLITCH

VOUT (20mV/div)

Time (2

µs/div)

THEORY OF OPERATION

DAC SECTION

The architecture consists of a string DAC followed by anoutput buffer amplifier. Figure 1 shows a block diagram of theDAC architecture.

RESISTOR STRING

The resistor string section is shown in Figure 2, it is simply astring of resistors, each of value R. The code loaded into theDAC register determines at which node on the string the voltageis tapped off to be fed into the output amplifier by closing oneof the switches connecting the string to the amplifier. It isensured monotonic because it is a string of resistors.

VDD

V

FB

DAC Register

REF (+)Resistor String

REF(–)

VOUT

OutputAmplifier

GND

FIGURE 1. DAC8501 Architecture.

The input coding to the DAC8501 is straight binary, so theideal output voltage is given by:

VOUT=VREF

D65536

(1)

where D = decimal equivalent of the binary code that isloaded to the DAC register; it can range from 0 to 65535.

FIGURE 2. Resistor String.

DAC8501

SBAS212A

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