74HC283N Datasheet, PDF (12/20 Pages) NXP Semiconductors – 4-bit binary full adder with fast carry

Philips Semiconductors
12. Waveforms
74HC283
4-bit binary full adder with fast carry
CIN, An, Bn,
input
V_M
Sn, COUT,
output
t_PHL
V_M
t_PLH
t_THL
t_TLH
001aab899
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
PULSE
V_I
GENERATOR
V_CC
V_O
D.U.T.
R_T
C_L
mna101
Fig 7.
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.
Load circuitry for switching times
Table 9:
Supply
V_CC
2.0 V
4.5 V
6.0 V
5.0 V
Test data
Input
V_I
V_CC
V_CC
V_CC
V_CC
t_r, t_f
6 ns
6 ns
6 ns
6 ns
Load
C_L
50 pF
50 pF
50 pF
15 pF
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
9397 750 13811
Product data sheet
Rev. 03 — 11 November 2004
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
12 of 20