NTE2055 Datasheet, PDF (3/4 Pages) NTE Electronics – Integrated Circuit CMOS, 3 1/2 Digit A/D Converter

Coded Condition
of MSD
+0
–0
+0 UR
–0 UR
+1
–1
+1 OR
–1 OR
Truth Table (DS1 =1)
Q3 Q2 Q1 Q0
1
1
1
0
1
0
1
0
1
1
1
1
1
0
1
1
0
1
0
0
0
0
0
0
0
1
1
1
0
0
1
1
BCD to 7 Segment
Decoding
Blank
Blank
Blank
Blank
4→1
0→1
Hook up
only seg b
7→1
3→1
and c to
MSD
Notes for Truth Table:
Q3 – ¹/₂ digit, low for “1”, high for “0”
Q2 – Polarity: “1” = positive, “0” = negative
Q0 – Out of range condition exists if Q0 =1. When used in conjunction with Q3 the type
of out of range condition is indicated, i.e., Q3 = 0 → OR or Q3 = 1 → UR.
When only segment b and c of the decoder are connected to the ¹/₂ digit of the display 4,
0, 7, and 3 appear as 1.
The overrange indication (Q3 = 0 and Q0 = 1) occurs when the count is greater than 1999,
e.g., 1.999V for a reference of 2V. The underrage indication, useful for autoranging circuits,
occurs when the count is less than 180, e.g., o.180V for a reference of 2V.
Caution: If the most significant digit is connected to a display other than a “1” only; such as
a full digit display, segments other than b and c must be disconnected. The BCD
ti seven decoder must blank on BCD inputs 1010 to 1111.
Pin Connection Diagram
V_{AG 1}
V_{ref 2}
V_{X 3}
R_{I 4}
R_I/C_{I 5}
C_{I 6}
C_O 1 ₇
C_O 2 ₈
DU 9
CLK 1 10
24 ^VDD
23 Q3
22 Q2
21 Q1
20 Q0
19 DS 1
18 DS 2
17 DS 3
16 DS 4
15 ^OR
CLK 2 11
V_{EE 12}
14 EOC
13 ^VSS