SN74LS85 4-Bit Magnitude Comparator The SN74LS85 is a 4-Bit Magnitude Camparator which compares two 4-bit words (A, B), each word having four Parallel Inputs (A0 - A3, B0 - B3); A3, B3 being the most significant inputs. Operation is not restricted to binary codes, the device will work with any monotonic code. Three Outputs are provided: "A greater than B" (OA > B), "A less than B" (OA < B), "A equal to B" (OA = B). Three Expander Inputs, IA > B, IA < B, IA = B, allow cascading without external gates. For proper compare operation, the Expander Inputs to the least significant position must be connected as follows: IA < B= IA > B = L, IA = B = H. For serial (ripple) expansion, the OA > B, OA < B and OA = B Outputs are connected respectively to the IA > B, IA < B, and IA = B Inputs of the next most significant comparator, as shown in Figure 1. Refer to Applications section of data sheet for high speed method of comparing large words. The Truth Table on the following page describes the operation of the SN74LS85 under all possible logic conditions. The upper 11 lines describe the normal operation under all conditions that will occur in a single device or in a series expansion scheme. The lower five lines describe the operation under abnormal conditions on the cascading inputs. These conditions occur when the parallel expansion technique is used. * Easily Expandable * Binary or BCD Comparison * OA > B, OA < B, and OA = B Outputs Available http://onsemi.com LOW POWER SCHOTTKY 16 1 PLASTIC N SUFFIX CASE 648 16 GUARANTEED OPERATING RANGES Symbol VCC Parameter Supply Voltage 1 Min Typ Max Unit 4.75 5.0 5.25 V 0 25 70 C TA Operating Ambient Temperature Range IOH Output Current - High - 0.4 mA IOL Output Current - Low 8.0 mA SOIC D SUFFIX CASE 751B ORDERING INFORMATION Device Semiconductor Components Industries, LLC, 1999 December, 1999 - Rev. 6 1 Package Shipping SN74LS85N 16 Pin DIP 2000 Units/Box SN74LS85D 16 Pin 2500/Tape & Reel Publication Order Number: SN74LS85/D SN74LS85 CONNECTION DIAGRAM DIP (TOP VIEW) VCC A3 B2 A2 A1 B1 A0 B0 16 15 14 13 12 11 10 9 NOTE: The Flatpak version has the same pinouts (Connection Diagram) as the Dual In-Line Package. 1 2 3 4 B3 IA<B IA=B IA>B 5 6 OA>B OA=B 8 7 OA<B GND LOADING (Note a) PIN NAMES A0 - A3, B0 - B3 IA = B IA < B, IA > B OA > B OA < B OA = B Parallel Inputs A = B Expander Inputs A < B, A > B, Expander Inputs A Greater than B Output B Greater than A Output A Equal to B Output HIGH LOW 1.5 U.L. 1.5 U.L. 0.5 U.L. 10 U.L. 10 U.L. 10 U.L. 0.75 U.L. 0.75 U.L. 0.25 U.L. 5 U.L. 5 U.L. 5 U.L. NOTES: a) 1 TTL Unit Load (U.L.) = 40 mA HIGH/1.6 mA LOW. LOGIC SYMBOL 10 12 13 15 9 11 14 1 4 2 3 A0 A1 A2 A3 B0 B1 B2 B3 IA>B OA>B IA<B OA<B IA=B OA=B VCC = PIN 16 GND = PIN 8 http://onsemi.com 2 5 7 6 SN74LS85 LOGIC DIAGRAM A3 B3 (15) (1) (5) A2 B2 (13) (14) (2) A<B (3) A=B (4) A>B A1 B1 (6) OA=B (12) (11) (7) A0 B0 OA>B OA<B (10) (9) TRUTH TABLE CASCADING INPUTS COMPARING INPUTS OUTPUTS A3,B3 A2,B2 A1,B1 A0,B0 IA>B IA<B IA=B OA>B OA<B OA=B A3>B3 A3<B3 A3=B3 A3=B3 A3=B3 A3=B3 A3=B3 A3=B3 A3=B3 A3=B3 A3=B3 A3=B3 A3=B3 X X A2>B2 A2<B2 A2=B2 A2=B2 A2=B2 A2=B2 A2=B2 A2=B2 A2=B2 A2=B2 A2=B2 X X X X A1>B1 A1<B1 A1=B1 A1=B1 A1=B1 A1=B1 A1=B1 A1=B1 A1=B1 X X X X X X A0>B0 A0<B0 A0=B0 A0=B0 A0=B0 A0=B0 A0=B0 X X X X X X X X H L X H L X X X X X X X X L H X H L X X X X X X X X L L H L L H L H L H L H L H L L L H L H L H L H L H L H L L H L L L L L L L L L L H L L http://onsemi.com 3 H = HIGH Level L = LOW Level X = IMMATERIAL A0 A1 A2 A3 B0 B1 B2 IA > B L L H IA < B SN74LS85 IA = B B3 A0 A1 A2 A3 B0 B1 B2 OA > B OA < B IA > B IA < B OA = B IA = B Bn B n1 B n2 B n3 An A n1 B3 A n2 A0 A1 A2 A3 B0 B1 B2 A n3 SN74LS85 B3 A>B A<B A=B OA > B OA < B OA = B SN74LS85 L = LOW LEVEL H = HIGH LEVEL Figure 1. Comparing Two n-Bit Words APPLICATIONS Figure 2 shows a high speed method of comparing two 24-bit words with only two levels of device delay. With the technique shown in Figure 1, six levels of device delay result when comparing two 24-bit words. The parallel technique can be expanded to any number of bits, see Table 1. Table 1 WORD LENGTH NUMBER OF PKGS. 1 - 4 Bits 5 - 24 Bits 25 - 120 Bits 1 2-6 8 - 31 NOTE: The SN74LS85 can be used as a 5-bit comparator only when the outputs are used to drive the A0-A3 and B0-B3 inputs of another SN74LS85 as shown in Figure 2 in positions #1, 2, 3, and 4. INPUTS (MSB) A20 A21 A22 A23 B20 B21 B22 B23 (LSB) A0 A1 A2 A3 B0 B1 B2 B3 L A0 A1 A2 A3 B0 B1 B2 B3 IA > B OA > B A19 A0 A1 A2 A3 B0 B1 B2 B3 IA > B OA > B L IA < B OA < B B19 IA < B H IA = B OA = B L IA = B #5 #1 OA < B OA = B NC INPUTS A5 A6 A7 A8 B5 B6 B7 B8 A4 B4 L A10 A11 A12 A13 B10 B11 B12 B13 A0 A1 A2 A3 B0 B1 B2 B3 OA > B #4 IA < B OA < B A9 IA > B IA = B OA = B B9 NC L A15 A16 A17 A18 B15 B16 B17 B18 A0 A1 A2 A3 B0 B1 B2 B3 OA > B #3 OA < B IA < B IA > B IA = B OA = B A0 A1 A2 A3 B0 B1 B2 B3 OA > B #2 OA < B IA < B IA > B A14 B14 NC IA = B L OA = B A0 A1 A2 A3 B0 B1 B2 B3 IA > B OA > B IA < B IA = B MSB = MOST SIGNIFICANT BIT LSB = LEAST SIGNIFICANT BIT L = LOW LEVEL H = HIGH LEVEL NC = NO CONNECTION Figure 2. Comparison of Two 24-Bit Words http://onsemi.com 4 #6 OA < B OA = B OUTPUTS NC SN74LS85 DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified) Limits Symbol Parameter VIH Input HIGH Voltage VIL Input LOW Voltage VIK Input Clamp Diode Voltage VOH Output HIGH Voltage VOL O Output LOW Voltage Min Typ Max 2.0 0.8 - 0.65 2.7 - 1.5 3.5 IOS Output Short Circuit Current (Note 1) ICC Power Supply Current Guaranteed Input HIGH Voltage for All Inputs V Guaranteed Input LOW Voltage for All Inputs V VCC = MIN, IIN = - 18 mA V VCC = MIN, IOH = MAX, VIN = VIH or VIL per Truth Table V IOL = 4.0 mA 0.35 0.5 V IOL = 8.0 mA 20 60 A VCC = MAX, VIN = 2.7 V mA VCC = MAX, VIN = 7.0 V - 0.4 - 1.2 mA VCC = MAX, VIN = 0.4 V -100 mA VCC = MAX 20 mA VCC = MAX 0.1 0.3 Input LOW Current A < B, A > B Other Inputs V 0.4 A < B, A > B Other Inputs IIL Test Conditions 0.25 Input HIGH Current A < B, A > B Other Inputs IIH Unit - 20 VCC = VCC MIN, VIN = VIL or VIH per Truth Table Note 1: Not more than one output should be shorted at a time, nor for more than 1 second. AC CHARACTERISTICS (TA = 25C, VCC = 5.0 V) Limits Symbol Parameter Min Typ Max Unit tPLH tPHL Any A or B to A < B, A > B 24 20 36 30 ns tPLH tPHL Any A or B to A = B 27 23 45 45 ns tPLH tPHL A < B or A = B to A > B 14 11 22 17 ns tPLH tPHL A = B to A = B 13 13 20 26 ns tPLH tPHL A > B or A = B to A < B 14 11 22 17 ns Test Conditions VCC = 5.0 V CL = 15 pF AC WAVEFORMS VIN 1.3 V 1.3 V tPHL VOUT 1.3 V VIN 1.3 V tPHL tPLH 1.3 V 1.3 V VOUT Figure 3. tPLH 1.3 V 1.3 V Figure 4. http://onsemi.com 5 SN74LS85 PACKAGE DIMENSIONS N SUFFIX PLASTIC PACKAGE CASE 648-08 ISSUE R NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION L TO CENTER OF LEADS WHEN FORMED PARALLEL. 4. DIMENSION B DOES NOT INCLUDE MOLD FLASH. 5. ROUNDED CORNERS OPTIONAL. -A- 16 9 1 8 B F C L S -T- SEATING PLANE K H G D M J 16 PL 0.25 (0.010) M T A M http://onsemi.com 6 DIM A B C D F G H J K L M S INCHES MIN MAX 0.740 0.770 0.250 0.270 0.145 0.175 0.015 0.021 0.040 0.70 0.100 BSC 0.050 BSC 0.008 0.015 0.110 0.130 0.295 0.305 0_ 10 _ 0.020 0.040 MILLIMETERS MIN MAX 18.80 19.55 6.35 6.85 3.69 4.44 0.39 0.53 1.02 1.77 2.54 BSC 1.27 BSC 0.21 0.38 2.80 3.30 7.50 7.74 0_ 10 _ 0.51 1.01 SN74LS85 PACKAGE DIMENSIONS D SUFFIX PLASTIC SOIC PACKAGE CASE 751B-05 ISSUE J -A- 16 9 1 8 -B- P NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSIONS A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. 8 PL 0.25 (0.010) M B S G R K F X 45 _ C -T- SEATING PLANE J M D 16 PL 0.25 (0.010) M T B S A S http://onsemi.com 7 DIM A B C D F G J K M P R MILLIMETERS MIN MAX 9.80 10.00 3.80 4.00 1.35 1.75 0.35 0.49 0.40 1.25 1.27 BSC 0.19 0.25 0.10 0.25 0_ 7_ 5.80 6.20 0.25 0.50 INCHES MIN MAX 0.386 0.393 0.150 0.157 0.054 0.068 0.014 0.019 0.016 0.049 0.050 BSC 0.008 0.009 0.004 0.009 0_ 7_ 0.229 0.244 0.010 0.019 SN74LS85 ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. 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