(LSB) values. Output coding is two-complement binary

with

1LSB

=

2.44mV

for

the

MAX115

and

1LSB = 1.22mV for the MAX116.

Output Demultiplexer

An output demultiplexer circuit is useful for isolating

data from one channel in a four-channel conversion

sequence. Figure 9’s circuit uses the external 16MHz

clock and the INT signal to generate four RD pulses

and a latch clock to save data from the desired chan-

nel. CS must be low during the four RD pulses. The

channel is selected with the binary coding of two

switches. A 16-bit 16373 latch simplifies layout.

Motor-Control Applications

Vector motor control requires monitoring of the individ-

ual phase currents. In their most basic application, the

MAX115/MAX116 simultaneously sample two currents

(CH1A and CH2A, Figure 10) and preserve the neces-

sary relative phase information. Only two of the three

phase currents have to be digitized because the third

component can be mathematically derived with a coor-

dinate transformation.

The circuit of Figure 10 shows a typical vector motor-

control application using all available inputs of the

MAX115/MAX116. CH1A and CH2A are connected

to two isolated Hall-effect current sensors and are a

2x4-Channel, Simultaneous-Sampling

12-Bit ADCs

12

______________________________________________________________________________________

PRE

CLR

HC161

1/2 HC74

ENP

ENT

LOAD

A

B

C

D

(LSB) 0

1

2

3

RCO

DQ

Q

CLR

P0

P1

P2

P3

P4

P5

P6

P7

HC688

P = Q

Q0

Q1

Q2

Q3

Q4

Q5

Q6

Q7

G

LATCH

CLOCK

(TO 16373 LATCH)

0

CH1

0

1

CH2

0

0

CH3

1

1

CH4

1

10k

Ω

EXTERNAL

CLOCK

EXTERNAL

CLOCK

RD

INT

Figure 9. Output Demultiplexer Circuit