SP8605KN データシートの表示（PDF） - Signal Processing Technologies

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SP8605KN

12-Bit Sampling A/D Converters

Signal Processing Technologies 

FEATURES...

The SP86XX Series are specified at sampling

rates of 333kHz (SP8603), 200kHz (SP8605) or

100kHz (SP8610). Conversion times are factory

set for 2.70µs, 4.7µs and 9.7µs maximum, re-

spectively, over temperature, and the high-

speed sampling input stage insures a total acqui-

sition and conversion time of 3µs, 5µs and 10µs

maximum, respectively, over temperature. Pre-

cision, laser-trimmed scaling resistors provide

industry-standard input ranges of 0V to +5V or

0V to +10V.

The 28-pin SP86XX Series are available in

narrow plastic DIP, and SOIC packages and it

operates from a single +5V supply. The SP86XX

Series are available in grades specified over the

0°C to +70°C commercial temperature ranges.

OPERATION

Basic Operation

Figure 1 shows the simple hookup circuit required

to operate the SP86XX Series in a 0V to +10V

range in the Convert Mode. A convert command

arriving on R/C puts the SP86XX Series in the

HOLD mode, and a conversion is started. This

pulse must be LOW for a minimum of 40ns.

Because this pulse establishes the sampling instant

of the A/D, it must have very low jitter. BUSY will

be held LOW during the conversion, and rises only

Input

D11

(MSB)

1 N.C.

2 IN 1

3 IN 2

N.C. 28

+5V

+5V 27

+5V 26

6.8µF +

0.1µF

4 VREF

N.C. 25

5 AGND BUSY 24

6 D11 (MSB) CS 23

Busy

7 D10

8 D9

R/C 22

HBE 21

Convert

Command

9 D8 D0 (LSB) 20

10 D7

D1 19

11 D6

D2 18

12 D5

D3 17

13 D4

14 N.C.

DGND 16

N.C. 15

Data

Out

D0

(LSB)

Figure 1. Basic 0V to 10V Operation

after the conversion is completed and the data has

been transferred to the output drivers. Thus, the

rising edge can be used to read the data from the

conversion. Also, during conversion, the BUSY

signal puts the output data lines in Hi-Z states and

inhibits the input lines. This means that pulses on

R/C are ignored, so that new conversions cannot be

initiated during a conversion.

The SP86XX Series will begin acquiring a new

sample just prior to the BUSY output rising, and

will track the input signal until the next conversion

is started.

In the Read Mode, R/C is kept normally LOW, and

a HIGH pulse is used to read data and initiate a

conversion. In this mode, the rising edge of R/C

will enable the output data pins, and the data from

the previous conversion becomes valid. The fall-

ing edge then puts the SP86XX Series in a hold

mode, and initiates a new conversion.

For use with an 8-bit bus, the data can be read out in two

bytes under the control of HBE. With a LOW input

on HBE, at the end of a conversion, the 8 LSBs of data

areloadedintotheoutputdriversonD throughD and

7

4

D3 through D0. Taking HBE HIGH then loads the 4

MSBs on D3 through D0, with D7 through D4 being

forced LOW.

Analog Input Ranges

The SP86XX Series offers two standard unipolar

input ranges: 0V to +10V and 0V to +5V. If a 10V

unipolar range is required, the analog input signal

should be connected to pin 2. A signal requiring a

5V unipolar range should be connected to pin 3. In

either case, the other pin of the two must be

grounded or connected to the adjustment circuits

described in the section on calibration.

Controlling The SP86XX Series

The SP86XX Series can be easily interfaced to most

microprocessor-based and other digital systems. The

microprocessor may take full control of each conver-

sion, or the SP86XX Series may operate in a stand-

alone mode, controlled only by the R/C input. Full

control consists of initiating the conversion and read-

ing the output data at user command, transmitting data

either all 12-bits in one parallel word, or in two 8-bit

bytes. The three control inputs (CS, R/C and HBE) are

all TTL/CMOS compatible. The functions of the

83

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