Fairchild Semiconductor 74F521CW, 74F521SJX, 74F521SJ, 74F521SCX, 74F521SC Datasheet

April 1988

Revised August 1999

74F521

8-Bit Identity Comparator

General Description

The 74F521 is an expandable 8-bit comparator. It compares two words of up to eight bits each and provides a LOW output when the two words match bit for bit. The expansion input IA=B also serves as an active LOW enable input.

Features

■Compares two 8-bit words in 6.5 ns typ

■Expandable to any word length

■20-pin package

Ordering Code:

Order Number	Package Number	Package Description
74F521SC	M20B	20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
74F521SJ	M20D	20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74F521MSA	MSA20	20-Lead Shrink Small Outline Package (SSOP), EIAJ TYPE II, 5.3mm Wide
74F521PC	N20A	20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide

Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.

Logic Symbols

Connection Diagram

IEEE/IEC

Comparator Identity Bit-8 74F521

© 1999 Fairchild Semiconductor Corporation

DS009545

www.fairchildsemi.com

74F521

Unit Loading/Fan Out

	Pin Names				Description	U.L.			Input IIH/IIL
						HIGH/LOW			Output IOH/IOL
	A0–A7			Word A Inputs		1.0/1.0			20 mA/-0.6 mA
	B0–B7			Word B Inputs		1.0/1.0			20 mA/-0.6 mA
	IA=B			Expansion or Enable Input (Active LOW)		1.0/1.0			20 mA/-0.6 mA
				Identity Output (Active LOW)		50/33.3			-1 mA/20 mA
	O	A=B
Truth Table
				Inputs			Output
			IA = B		A, B			OA = B
				L	A = B (Note 1)				L
				L	A ¹ B				H
				H	A = B (Note 1)				H
				H	A ¹ B				H
H = HIGH Voltage Level
L = LOW Voltage Level

Note 1: A0 = B0, A1 = B1, A2 = B2, etc.

Logic Diagram

Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.

www.fairchildsemi.com

2

Absolute Maximum Ratings(Note 2)

Storage Temperature	−65°C to +150°C
Ambient Temperature under Bias	−55°C to +125°C
Junction Temperature under Bias	−55°C to +150°C
VCC Pin Potential to Ground Pin	−0.5V to +7.0V
Input Voltage (Note 3)	−0.5V to +7.0V
Input Current (Note 3)	−30 mA to +5.0 mA
Voltage Applied to Output
in HIGH State (with VCC = 0V)
Standard Output	−0.5V to VCC
3-STATE Output	−0.5V to +5.5V
Current Applied to Output
in LOW State (Max)	twice the rated IOL (mA)

Recommended Operating

Conditions

Free Air Ambient Temperature	0°C to +70°C
Supply Voltage	+4.5V to +5.5V

Note 2: Absolute maximum ratings are values beyond which the device may be damaged or have its useful life impaired. Functional operation under these conditions is not implied.

Note 3: Either voltage limit or current limit is sufficient to protect inputs.

DC Electrical Characteristics

Symbol	Parameter		Min	Typ	Max	Units	VCC	Conditions
VIH	Input HIGH Voltage		2.0			V		Recognized as a HIGH Signal
VIL	Input LOW Voltage				0.8	V		Recognized as a LOW Signal
VCD	Input Clamp Diode Voltage				−1.2	V	Min	IIN = −18 mA
VOH	Output HIGH	10% VCC	2.5			V	Min	IOH = −1 mA
	Voltage	5% VCC	2.7					IOH = −1 mA
VOL	Output LOW	10% VCC			0.5	V	Min	IOL = 20 mA
	Voltage
IIH	Input HIGH Current				5.0	μA	Max	VIN = 2.7V
IBVI	Input HIGH Current				7.0	μA	Max	VIN = 7.0V
	Breakdown Test
ICEX	Output HIGH				50	μA	Max	VOUT = VCC
	Leakage Current
VID	Input Leakage		4.75			V	0.0	IID = 1.9 μA
	Test							All Other Pins Grounded
IOD	Output Leakage				3.75	μA	0.0	VIOD = 150 mV
	Circuit Current							All Other Pins Grounded
IIL	Input LOW Current				−0.6	mA	Max	VIN = 0.5V
IOS	Output Short-Circuit Current		−60		−150	mA	Max	VOUT = 0V
ICCH	Power Supply Current			21	32	mA	Max	VO = HIGH

74F521

3	www.fairchildsemi.com