NTE2028
Integrated Circuit
7Segment High Voltage Decoder/Driver
Description:
The NTE2028 is an integrated circuit in a 16Lead DIP type package custom designed to decode
four lines of BCD and drive a gasfilled sevensegment display tube.
Each output constitutes a switchable, adjustable current sink which provides constant current to the
tube segment, even with high tube anode supply tolerance or fluctuation. These current sinks have
a voltage compliance from 3V to at least 80V; typically the output current varies 1% for output voltage
changes of 3 to 50V. Each bit line of the decoder switches a current sink on or off as prescribed by
the input code. Each current sink is ratioed to the boutput current as required for even illumination
of all segments.
Output currents may be varied over the 0.2 to 1.5 mA range for driving various tube types or multiplex
operation. The output current is adjusted by connecting an external program resistor (R
p
) from V
CC
to the Program input in accordance with the programming curve. The circuit design provides a one
toone correlation between program input current and bsegment output current.
The Blanking Input provides unconditional blanking of any output display, while the Ripple Blanking
pins allow simple leading or trailing zero blanking.
Features:
D
Current Sink Outputs
D
Adjustable Output Current: 0.2 to 1.5mA
D
High Output Breakdown Voltage: 110V Typ
D
Suitable for Multiplex Operation
D
Blanking and Ripple Blanking Provisions
D
Low FanIn and Low Power
Absolute Maximum Raings: (Note 1)
Supply Voltage, V
CC
7V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Voltage (Except BI)
6V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Voltage (BI)
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Segment Output Voltage
80V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Dissipation, P
D
600mW
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transient Segment Output Current (Note 2)
50mA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage Temperature Range, T
stg
65
to +150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead Temperature (During Soldering, 10sec), T
L
+300
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Note 1. "Absolute Maximum Ratings" are those values beyond which the safety of the device cannot
be guaranteed. Except for "Operating Temperature Range" they are not meant to imply that
the device should be operated at these limits. The table of "Electrical Chracteristics" pro-
vides conditions for actual device operation.
Note 2. In all applications transient segment output current must be limited to 50mA. This may be
accomplished in DC applications by connecting a 2.2k resistor from the anodesupply filter
capacitor to the display anode, or by current limiting the anode driver in multiplex applica-
tions.
Recommended Operating Conditions:
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Supply Voltage
V
CC
4.75
5.25
V
Operating Temperature
T
A
0
70
C
Electrical Characteristics: (Note 3, Note 4)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Logical "1" Input Voltage
V
IH
V
CC
= Min
2.0
V
Logical "0" Input Voltage
V
IL
V
CC
= Min
0.8
V
Logical "1" Output Voltage
V
OH
V
CC
= Min, I
OUT
= 200
A, RBO
2.4
3.7
V
Logical "0" Output Voltage
V
OL
V
CC
= Min, I
OUT
= 8mA, RBO
0.13
0.4
V
Logical "1" Input Current
I
IH
V
CC
= Max, Except BI
V
IN
= 2.4V
2
15
A
V
IN
= 5.5V
4
400
A
Logical "0" Input Current
I
IL
V
CC
= Max, V
IN
= 0.4V
Except BI
300
600
A
BI
1.2
2.0
mA
Power Supply Current
I
CC
V
CC
= Max, R
P
= 2.2k, All Inputs = 0V
27
43
mA
Input Diode Clamp Voltage
V
CD
V
CC
= Max, T
A
= +25
C, I
IN
= 12mA
0.9
1.5
V
Segment Outputs "ON" Current Ratio
I
O
All Outputs = 50V,
Outputs a, f, g
0.84
0.93
1.02
I
OUT
b = Ref
Output c
1.12
1.25
1.38
Output d
0.90
1.00
1.10
Output e
0.99
1.10
1.21
Output b "ON" Current
I
b ON
V
CC
= 5V,
R
P
= 18.1k
0.15
0.20
0.25
mA
V
OUT
b = 50V,
All Other Outputs
5V, R
P
= 7.03k
0.45
0.50
0.55
mA
All Other Outputs
5V,
T
A
= +25
C
R
P
= 3.40k
0.90
1.00
1.10
mA
R
P
= 2.20k
1.35
1.50
1.65
mA
Output Saturation Voltage
V
SAT
V
CC
= Min, R
P
= 1k
5%,
I
OUT
b = 2mA, Note 5
0.8
2.5
V
Output Leakage Current
I
CEX
V
OUT
= 75V, BI = 0V, R
P
= 2.2k
0.003
3.0
A
Output Breakdown Voltage
V
BR
I
OUT
= 250
A, BI = 0V, R
P
= 2.2k
80
110
V
Propagation Delays
BCD Input to Segment Output
t
pd
V
CC
= 5V, T
A
= +25
C
0.4
10
s
BI to Segment Output
0.4
10
s
RBI to Segment Output
0.7
10
s
RBI to RBO
0.4
10
s
Note 3. Unless otherwise specified, Min/Max limits apply across T
A
= 0
to +70
C. All typical values
are or T
A
= +25
C and V
CC
= 5V.
Note 4. All currents into device pins ahown as positive, out of device pins as negative, all voltages
referenced to GND unless otherwise sepcified. All values shown as Max or Min on absolute
value basis.
Note 5. For saturation mode the segment output currents are externally limited and ratioed.
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