28128 Parallax Inc, 28128 Datasheet - Page 91

• Manufacturer Part Number: 28128
• Description: KIT BASIC ANALOG/DIGI PARTS ONLY
• Manufacturer: Parallax Inc

Specifications of 28128

• Accessory Type: ADC, DAC
• Product: Microcontroller Accessories
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

increases. Third, the largest error is 0.1 volts. This kind of data can be exceedingly useful
in electronics design, and the automated testing process is a huge time saver.
The Voltage Follower
Let's use the voltage sweep to analyze what happens when the output of the D/A
converter is connected to another circuit. We'll use the output of the D/A converter to
drive an LED circuit. First we'll connect the D/A converter output directly to the input of
the LED circuit. Then we'll use the voltage follower as an intermediate step between the
D/A converter output and the LED circuit input.
P0
P1
P2
1
7
6
Vdd
/CS
CLK
D0
ADC0831
8
Vref
Vdd
Vin(+)
5
GND
Vin(-)
Figure 4-7 D/A Circuit without a Buffer.
2
4
3
Vss
P7
P6
P5
P4
2 k
2 k
2 k
2 k
Ω
Ω
Ω
Ω
Vss
1 k
1 k
1 k
2 k
Ω
Ω
Ω
Ω
Vss
2 k
Ω
Vss
270
LED
Ω