NE531FE Ver la hoja de datos (PDF) - Philips Electronics

Número de pieza

componentes Descripción

Fabricante

NE531FE

High slew rate operational amplifier

Philips Electronics 

Philips Semiconductors Linear Products

High slew rate operational amplifier

Product specification

NE/SE531

CYCLIC A-TO-D CONVERTER

One interesting, but much ignored, A/D converter is the cyclic

converter. This consists of a chain of identical stages, each of which

senses the polarity of the input. The stage then subtracts VREF from

the input and doubles the remainder if the polarity was correct. In

Figure 1, the signal is full-wave rectified and the remainder of

VIN-VREF is doubled. A chain of these stages gives the gray code

equivalent of the input voltage in digitized form related to the

magnitude of VREF. Possessing high potential accuracy, the circuit

using NE531 devices settles in 5µs.

TRIANGLE AND SQUARE WAVE GENERATOR

The circuit in Figure 2 will generate precision triangle and square

waves. The output amplitude of the square wave is set by the output

+vcc

10K

LOGIC OUT

+

NE531

–

10K

+

NE531

2K

–

20K

swing of op amp A-1, and R1/R2 sets the triangle amplitude. The

frequency of oscillation in either case is:

f

+

1

4RC

@

R2

R1

(1)

The square wave will maintain 50% duty cycle even if the amplitude

of the oscillation is not symmetrical.

The use of the NE531 in this circuit will allow good square waves to

be generated to quite high frequencies. Since the amplifier A1 runs

open-loop, there is no need for compensation. The

triangle-generating amplifier must be compensated. The NE5535

device can be used as well, except for the lower frequency

response.

–VIN

VOUT

VREF

0

VREF

VIN

VREF

20K

LOGOUT

VIN

VREF

a.

b.

Figure 1. Cyclic A-to-D Converter

August 31, 1994

77

Share Link: