icl8068a Intersil Corporation, icl8068a Datasheet - Page 20

• Manufacturer Part Number: icl8068a
• Description: Precision 4 1/2 Digit, A/d Converter
• Manufacturer: Intersil Corporation

ICL71C03 with ICL8052A/8068A Integrating A/D Converter Equations
The ICL71C03 does not have an internal crystal or RC
oscillator. It has a clock input only.
Integration Period
Integration Clock Period
60/50Hz Rejection Criterion
Optimum Integration Current
Full Scale Analog Input Voltage
Integrate Resistor
Integrate Capacitor
t
t
I
V
t
t
CLOCK
INT
INT
R
C
I NT
I NT
INFS
I NT
I NT
/t
= 20µA
60Hz
=
=
=
=
(Typ) = 200mV to 2.0V = 2V
-------------------- - 4-1/2 Digit
f
-------------------- - 3-1/2 Digit
f
10 000
CLOCK
CLOCK
= 1/f
1 000
(
------------------------------------------------------------ -
(
------------------------------- -
BufferG ain
t
,
I NT
,
or t
V
CLOCK
INT
) I
INT
(
(
(
INT
I
/t
I NT
50Hz
)
)
×
V
= Integer
IN FS
)
)
20
30,001 - 10,001
3,001 - 1,001
AUTO ZERO
ICL8052A/ICL71C03, ICL8068A/ICL71C03
(COUNTS)
REF
t
t
CONV
CONV
TOTAL CONVERSION TIME (t
FIGURE 20. INTEGRATOR OUTPUT
= 40,002 * t
= 4,002 * t
(FIXED COUNT)
(IN CONTINUOUS MODE)
INTEGRATE
10,000
1,000
CLOCK
CLOCK
(3
(4
1
1
/
/
2
2
DIGIT MODE)
Integrator Output Voltage
Output Count
NOTE: The 4
Output Type:
Power Supply: ±15V, +5V
Auto Zero Capacitor Values
Reference Capacitor Value
DIGIT MODE)
DEINTEGRATE
V
4 Nibbles BCD with Polarity and Over-range.
V++ = +15V
V- = -15V
V+ = +5V
V
If V
0.01µF < C
C
CONV
V
Count
Count
(COUNTS)
1 - 20,001
INT
REF
REF
1 - 2,001
I NT
REF
digit mode.
)
(Typ) = 9V
=
≅ 1.75V
= (Buffer Gain) x C
=
=
not used, float output pin.
(
------------------------------- -
t
INT
10 000
1 000
1
,
/
AZ
C
2
,
digit mode’s LSD will be output as a zero in the 3
) I
INT
(
< 1µF
IN T
×
(4
(3
×
-------------- -
V
1
1
V
-------------- -
V
)
/
/
REF
2
2
V
IN
REF
DIGIT)
DIGIT)
I N
(3-1/2 Digit)
(4-1/2 Digit)
AZ
1
/
2