XD74LS85

XD74LS85 DIP-16 This four bit magnitude comparator performs comparison of straight binary and straight BCD (8-4-2-1) codes. Three fully decoded decisions about two 4-bit words (A, B) are made and are externally available at three outputs. This device is fully expandable to any number of bits without external gates. Words of greater length may be compared by connecting comparators in cascade. The A > B, A < B, and A = B outputs of a stage handling less-significant bits. The stage handling the least- significant bits must have a high-level voltage applied to the A β B input. The cascading path is implemented with only a two-gate-level delay to reduce overall comparison times for long words. Pin Arrangement B3 Data Input 1 AB A2 13 A2 A>B 5 A>B A1 12 A1 A=B 6 A=B Out B1 11 B1 A B2 X A2 < B2 X A2 = B2 A1 > B1 A2 = B2 A1 < B1 A2 = B2 A1 = B1 A2 = B2 A1 = B1 A2 = B2 A1 = B1 A2 = B2 A1 = B1 A2 = B2 A1 = B1 A2 = B2 A1 = B1 A2 = B2 A1 = B1 A0, B0 X X X X X X A0 > B0 A0 < B0 A0 = B0 A0 = B0 A0 = B0 A0 = B0 A0 = B0 Cascading Inputs A>B AB H L H L H L H L H L L L H Outputs AB A2 B2 AB A=B A1 B1 A B inputs Other inputs IIH A < B, A > B inputs Other inputs IIL A < B, A > B inputs Other inputs II Short-circuit output current Supply current** Input clamp voltage Condition VCC = 4.75 V, VIH = 2 V, VIL = 0.8 V, IOH = –400 µA IOL = 4 mA VCC = 4.75 V, VIH = 2 V, VIL = 0.8 V IOL = 8 mA µA VCC = 5.25 V, VI = 2.7 V mA VCC = 5.25 V, VI = 0.4 V mA VCC = 5.25 V, VI = 7 V –100 mA VCC = 5.25 V 20 –1.5 mA V VCC = 5.25 V VCC = 4.75 V, IIN = –18 mA Note: * VCC = 5 V, Ta = 25°C ** ICC is measured with outputs open, A = B grounded, and all other inputs at 4.5 V. Switching Characteristics (VCC = 5 V, Ta = 25°C) Item Symbol Inputs Outputs tPLH Any A or B data input A < B, A > B Number of gate levels min. typ. max. Unit Condition 1 2 3 4 1 2 3 4 1 1 2 2 1 1 — — — — — — — — — — — — — — 14 19 24 27 11 15 20 23 14 11 13 13 14 11 — — 36 45 — — 30 45 22 17 20 26 22 17 ns CL = 15 pF, RL = 2 kΩ A=B Propagation delay time tPHL Any A or B data input A < B, A > B A=B tPHL tPHL tPLH tPHL tPLH tPHL A < B or A=B A>B A=B A=B A > B or A=B AB CL Output Same as Load Circuit 1. A=B Output Same as Load Circuit 1. AB GND GND GND GND GND GND 4.5 v GND GND GND IN GND GND A=B GND GND GND GND GND GND GND GND 4.5 v 4.5 v GND IN GND Output waveforms AB A=B A