HI7131_02 Datasheet, PDF (8/25 Pages) Intersil Corporation – 3 1/2 Digit, Low Power, High CMRR, LCD/LED Display-Type A/D Converters

HI7131, HI7133
Pin Descriptions
PIN NUMBER
44 PIN
40 PIN DIP FLATPACK
24
31
25
32
26
34
27
35
28
36
29
37
30
38
31
39
32
40
33
41
34
42
35
43
36
44
37
3
38
4
39
6
40
7
NAME
C3
G2
V-
INT
BUFF
A-Z
IN LO
IN HI
COMMON
C_REF-
C_REF+
REF LO
REF HI
TEST
OSC3
OSC2
OSC1
FUNCTION
Output
Output
Supply
Output
Output
Input
Input
Supply/
Output
Input
Input
Output
Output
Input
DESCRIPTION
Driver pin for segment “C” of the display hundreds digit.
Driver pin for segment “G” of the display tens digit.
Negative power supply.
Integrator amplifier output. To be connected to integrating capacitor.
Input buffer amplifier output. To be connected to integrating resistor.
Integrator amplifier input. To be connected to auto-zero capacitor.
Differential inputs. To be connected to input voltage to be measured. LO and HI
designators are for reference and do not imply that LO should be connected to
lower potential, e.g., for negative inputs IN LO has a higher potential than IN HI.
Internal voltage reference output.
Connection pins for reference capacitor.
Input pins for reference voltage to the device. REF HI should be positive
reference to REF LO.
Display test. Turns on all segments when tied to V+.
Device clock generator circuit connection pins.
Definition of Specifications
Count
A Count is equal to one number change in the least signifi-
cant digit of the display. The analog size of a count referred
to ADC input is:
Analog Count Size = ^F-_M---^u--_a--^l-^lx---^S--_R--^c---_ea---_al-^e--_d---_iR--_n---^ag---ⁿ--+-^g----_1e-- ,
Max reading +1 for a 3¹/₂ digit display is 2000 (1999+1).
Zero Input Reading
The reading of the ADC display when input voltage is zero
and there is no common mode voltage, i.e., the inputs are
shorted to COMMON pin.
Ratiometric Reading
The reading of the ADC display when input voltage is equal
to reference voltage, i.e., IN HI tied to REF HI and IN LO tied
to REF LO and COMMON pins. The accuracy of reference
voltage is not important for this test.
Rollover Error
Difference in the absolute value reading of ADC display for
equal magnitude but opposite polarity inputs. The input volt-
age should be close to full scale, which is the worst case
condition.
Linearity
Deviation of the ADC transfer function (output reading
versus input voltage transfer plot) from the best straight line
fitted to ADC transfer plot.
Scale Factor Temperature Coefficient
The rate of change of the slope of ADC transfer function due
to the change of temperature.
Equivalent Input Noise
The total random uncertainty of the ADC for converting a
fixed input value to an output reading. This uncertainty is
referred to input as a noise source which produces the
equivalent effect. It is given for zero input and is expressed
as Peak-to-Peak noise value and submultiples of Counts.
Overload Recovery Period
A measure of how fast the ADC will display an accurate
reading when input changes from an overload condition to a
value within the range. This is given as the number of con-
version cycles required after the input goes within the range.
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