MC14549B Ver la hoja de datos (PDF) - Motorola => Freescale

Número de pieza

componentes Descripción

Fabricante

MC14549B

Successive Approximation Registers

Motorola => Freescale 

Sout

SC

C

Sout

MC14559B

Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0 FF EOC

C

SC

Sout

MC14549B

MR

Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0 EOC

TO DAC

TO DAC

EOC

Figure 4. Continuously Cycling 12–Bit ADC

the 12–bit conversion cycle, the end of the serial output

word, and the validity of the parallel data output.

Externally Controlled 12–Bit ADC (Figure 5)

In this circuit the external pulse starts the first SAR and

simultaneously resets the cascaded second SAR. When Q4

of the first SAR goes high, the second SAR starts conver-

sion, and the first one stops conversion. EOC indicates that

the parallel data are valid and that the serial output is com-

plete. Updating the output data is started with every external

control pulse.

Additional Motorola Parts for Successive

Approximation ADC

Monolithic digital–to–analog converters — The

MC1408/1508 converter has eight–bit resolution and is avail-

able with 6, 7, and 8–bit accuracy. The amplifier–compara-

tor block — The MC1407/1507 contains a high speed

operational amplifier and a high speed comparator with ad-

justable window.

With these two linear parts it is possible to construct SA–

ADCs with an accuracy of up to eight bits, using as the regis-

ter one MC14549B or one MC14559B. An additional CMOS

block will be necessary to generate the clock frequency.

Additional information on successive approximation ADC

is found in Motorola Application Note AN–716.

SC

C

Sout

MC14559B

Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0 FF EOC

C

SC

Sout

MC14549B

MR

Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0 EOC

TO DAC

TO DAC

Figure 5. Externally Controlled 12–Bit ADC

EOC Sout

MOTOROLA CMOS LOGIC DATA

MC14549B MC14559B

7

Share Link: