NTE2028
Integrated Circuit
7–Segment High Voltage Decoder/Driver
Description:
The NTE2028 is an integrated circuit in a 16–Lead DIP type package custom designed to decode
four lines of BCD and drive a gas–filled seven–segment 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 b–output 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 (Rp) from VCC
to the Program input in accordance with the programming curve. The circuit design provides a one–
to–one correlation between program input current and b–segment 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 Fan–In and Low Power
Absolute Maximum Raings: (Note 1)
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V
Input Voltage (Except BI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V
Input Voltage (BI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VCC
Segment Output Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80V
Power Dissipation, PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 600mW
Transient Segment Output Current (Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA
Storage Temperature Range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65° to +150°C
Lead Temperature (During Soldering, 10sec), TL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +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” provides 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 anode–supply filter
capacitor to the display anode, or by current limiting the anode driver in multiplex applications.
Recommended Operating Conditions:
Parameter
Supply Voltage
Symbol
Min
Typ
Max
Unit
VCC
4.75
–
5.25
V
TA
0
–
70
°C
Min
Typ
Max
Unit
Operating Temperature
Test Conditions
Electrical Characteristics: (Note 3, Note 4)
Parameter
Symbol
Test Conditions
Logical “1” Input Voltage
VIH
VCC = Min
2.0
–
–
V
Logical “0” Input Voltage
VIL
VCC = Min
–
–
0.8
V
Logical “1” Output Voltage
VOH
VCC = Min, IOUT = –200µA, RBO
2.4
3.7
–
V
Logical “0” Output Voltage
VOL
VCC = Min, IOUT = 8mA, RBO
–
0.13
0.4
V
VIN = 2.4V
–
2
15
µA
VIN = 5.5V
–
4
400
µA
Except BI
–
–300 –600
µA
BI
–
–1.2
–2.0
mA
Logical “1” Input Current
Logical “0” Input Current
IIH
IIL
VCC = Max, Except BI
VCC = Max, VIN = 0.4V
Power Supply Current
ICC
VCC = Max, RP = 2.2k, All Inputs = 0V
–
27
43
mA
Input Diode Clamp Voltage
VCD
VCC = Max, TA = +25°C, IIN = –12mA
–
–0.9
–1.5
V
Outputs a, f, g
0.84
0.93
1.02
Output c
1.12
1.25
1.38
Output d
0.90
1.00
1.10
Output e
0.99
1.10
1.21
RP = 18.1k
VCC = 5V,
VOUTb = 50V,
All Other Outputs ≥ 5V, RP = 7.03k
TA = +25°C
RP = 3.40k
0.15
0.20
0.25
mA
0.45
0.50
0.55
mA
0.90
1.00
1.10
mA
RP = 2.20k
1.35
1.50
1.65
mA
Segment Outputs “ON” Current Ratio
Output b “ON” Current
IO
Ib ON
All Outputs = 50V,
IOUTb = Ref
Output Saturation Voltage
VSAT
VCC = Min, RP = 1k ±5%,
IOUTb = 2mA, Note 5
–
0.8
2.5
V
Output Leakage Current
ICEX
VOUT = 75V, BI = 0V, RP = 2.2k
–
0.003
3.0
µA
Output Breakdown Voltage
VBR
IOUT = 250µA, BI = 0V, RP = 2.2k
80
110
–
V
VCC = 5V, TA = +25°C
–
0.4
10
µs
BI to Segment Output
–
0.4
10
µs
RBI to Segment Output
–
0.7
10
µs
RBI to RBO
–
0.4
10
µs
Propagation Delays
BCD Input to Segment Output
tpd
Note 3. Unless otherwise specified, Min/Max limits apply across TA = 0° to +70°C. All typical values
are or TA = +25°C and VCC = 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.
Truth Table:
Decimal
or
Function
RBI{
D
C
B
A
BI/RBO
a
b
c
d
e
f
g
0
1
0
0
0
0
1
0
0
0
0
0
0
1
1
X
0
0
0
1
1
1
0
0
1
1
1
1
2
X
0
0
1
0
1
0
0
1
0
0
1
0
3
X
0
0
1
1
1
0
0
0
0
1
1
0
4
X
0
1
0
0
1
1
0
0
1
1
0
0
5
X
0
1
0
1
1
0
1
0
0
1
0
0
6
X
0
1
1
0
1
0
1
0
0
0
0
0
7
X
0
1
1
1
1
0
0
0
1
1
1
1
8
X
1
0
0
0
1
0
0
0
0
0
0
0
9
X
1
0
0
1
1
0
0
0
0
1
0
0
10
X
1
0
1
0
1
0
0
0
1
0
0
0
11
X
1
0
1
1
1
1
1
0
0
0
0
0
12
X
1
1
0
0
1
0
1
1
0
0
0
1
13
X
1
1
0
1
1
1
0
0
0
0
1
0
14
X
1
1
1
0
1
0
1
1
0
0
0
0
15
X
1
1
1
1
1
0
1
1
1
0
0
0
BI *
X
X
X
X
X
0*
1
1
1
1
1
1
1
RBI
0
0
0
0
0
0
1
1
1
1
1
1
1
* BI/RBO used as input only.
{ X = Don’t care.
Pin Connection Diagram
Input B 1
16 VDD
Input C 2
Input Program 3
15 Output f
14 Output g
BI/RBO 4
13 Output a
Input RBI 5
12 Output b
Input D 6
11 Output c
Input A 7
10 Output d
GND 8
9 Output e
Display
16
9
1
8
.870 (22.0) Max
.260 (6.6)
Max
.200 (5.08)
Max
.100 (2.54)
.700 (17.78)
.099 (2.5) Min