
HCF4033B
2/11
INPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
PIN No
SYMBOL
NAME AND FUNCTION
1
CLOCK
Clock Input
7 - Segments Decoded
Outputs
10, 12, 13, 9,
11, 6, 7
a to g
2
CLOCK
INHIBIT
RESET
RIPPLE
BLANKING
IN
CARRY OUT Carry Out Output
RIPPLE
BLANKING
OUT
LAMP TEST Lamp Test Input
V
SS
Negative Supply Voltage
V
DD
Positive Supply Voltage
Clock Inhibit Input
15
Reset Input
3
Ripple Blanking Input
5
4
Ripple Blanking Output
14
8
16
The seven decoded outputs (a, b, c, d, e, f, g)
illuminate the proper segments in a seven
segment display device used for representing the
decimal numbers 0 to 9. The 7-segment outputs
go high on selection. This device has provisions
for automating blanking of the non-significant
zeros in a multi digit decimal number which results
in a easily readable display consistent with normal
writing practice. For example, the number
0050.07000 in an eight digit display would be
displayed as 50.07. Zero suppression on the
integer side is obtained by connecting the RBI
terminal of the HCF4033B associated with the
most significant digit in the display to a low level
voltage and connecting the RBO terminal of that
stage to the RBI terminal of the HCF4033B in the
next lower significant position in the display. This
procedure is continued for each succeeding
HCF4033B on the integer side of the display. On
the fraction side of the display the RBI of the
HCF4033B associated with the least significant bit
is connected to a low level voltage and the RBO of
that HCF4033B is connected to the RBI terminal
of the HCF4033B in the next more significant bit
position. Again, this procedure is continued for all
HCF4033B’s on the fraction side of the display. In
a purely fractional number the zero immediately
preceding the decimal point can be displayed by
connecting the RBI of that stage to a high level
voltage (instead of to the RBO of the next more
significant stage). For example : optional zero
→
0.7346. Likewise, the zero in a number such as
763.0 can be displayed by connecting the RBI of
the HCF4033B associated with it to a high level
voltage. Ripple blanking of non-significant zeros
provides an appreciable savings in display power.
The HCF4033B has a LAMP TEST input which,
when connected to a high level voltage, overrides
normal decoder operation and enables a check to
be made on possible display malfunctions by
putting the seven outputs in the high state.