9397 750 13811 © Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Product data sheet Rev. 03 — 11 November 2004 12 of 20
Philips Semiconductors
74HC283
4-bit binary full adder with fast carry
12. Waveforms
13. Application information
Figure 8 shows a 3-bit adder using the 74HC283. Trying the operand inputs of the fourth
adder (A4 and B4) LOW makes S4 dependent on, and equal to, the carry from the third
adder.
Figure 9, based on the same principle, shows a method of dividing the 74HC283 into a
2-bit and 1-bit adder. The third stage adder (A3, B3 and S3) is used simply as means of
transferring the carry into the fourth stage (via A3 and B3) and transferring the carry from
V
M
= 0.5 × V
I
.
Fig 6. Waveforms showing the inputs (CIN, An and Bn) to the outputs (Sn and COUT)
propagation delays and the output transition times
Test data is given in Table 9.
Definitions for test circuit:
R
T
= Termination resistance should be equal to output impedance Z
o
of the pulse generator.
C
L
= Load capacitance including jig and probe capacitance.
Fig 7. Load circuitry for switching times
Table 9: Test data
Supply Input Load
V
CC
V
I
t
r
, t
f
C
L
2.0 V V
CC
6 ns 50 pF
4.5 V V
CC
6 ns 50 pF
6.0 V V
CC
6 ns 50 pF
5.0 V V
CC
6 ns 15 pF
001aab899
CIN, An, Bn,
input
Sn, COUT,
output
V
M
t
PHL
t
THL
t
TLH
t
PLH
V
M
mna101
V
CC
V
I
V
O
R
T
C
L
PULSE
GENERATOR
D.U.T.
