HI7131CM44 INTERSIL [Intersil Corporation], HI7131CM44 Datasheet - Page 16

• Manufacturer Part Number: HI7131CM44
• Description: 3 1/2 Digit, Low Power, High CMRR, LCD/LED Display-Type A/D Converters
• Manufacturer: INTERSIL [Intersil Corporation]

In many applications where the A/D is connected to a trans-
ducer, there will exist a scale factor other than unity between
the input voltage and the digital reading. For instance, in a
weighing system, the designer might like to have a full scale
reading when the voltage from the transducer is 0.682V.
Instead of dividing the input down to 200.0mV, the designer
should use the input voltage directly and adjust the V
0.341V. Suitable values for integrating resistor and capacitor
would be 620k and 0.047 F. This makes the system slightly
quieter and also avoids a divider network on the input.
The on-chip voltage reference (V+ - V
used to provide the converter reference voltage. However,
some applications may desire to use an external reference
generator. Various possible schemes exist for reference volt-
age settings. Figure 11 shows the normal way of using on-
chip reference and also a way of using external reference.
The value of resistors on both circuit depends on the con-
verter input voltage range. Refer to “Typical Applications”
section for various schemes.
Typical Applications
The HI7131 and HI7133 A/D Converters may be used in a
wide variety of configurations. The following application
HI7131/33
COMMON
V+
REF LO
REF HI
V+
FIGURE 99. HI7131 TYPICAL REFERENCE CIRCUITS
COMMON
See “Typical Applications” section for
resistance values for different ranges.
) is normally
HI7131, HI7133
REF
for
3-1841
circuits show some of the possibilities, and serves to illus-
trate the exceptional versatility of these devices.
The following application notes contain very useful informa-
tion on understanding and applying these parts and are
available from Intersil Corporation.
Application Notes
NOTE #
AN016
AN017
AN018
AN032
AN052
“Selecting A/D Converters”
“The Integrating A/D Converter”
“Do’s and Don’ts of Applying A/D
Converters”
“Understanding the Auto-Zero and
Common Mode Performance of the
ICL7136/7/9 Family”
“Tips for Using Single Chip 3
Converters”
HI7131/33
COMMON
V+
DESCRIPTION
REF LO
REF HI
20k
1
/
2
Digit A/D
V+
27K
1.2V
REFERENCE
ICL8069
AnswerFAX
DOC. #
9016
9017
9018
9032
9052