Fairchild Semiconductor FST3245CW, FST3245WMX, FST3245WM, FST3245QSCX, FST3245QSC Datasheet

June 1997

Revised December 1999

FST3245

Octal Bus Switch

General Description

The Fairchild Switch FST3245 provides 8-bits of highspeed CMOS TTL-compatible bus switching in a standard ’245 pin-out. The low on resistance of the switch allows inputs to be connected to outputs without adding propagation delay or generating additional ground bounce noise.

The device is organized as an 8-bit switch. When OE is LOW, the switch is ON and Port A is connected to Port B. When OE is HIGH, the switch is OPEN and a high-imped- ance state exists between the two ports.

Features

■4Ω switch connection between two ports.

■Minimal propagation delay through the switch.

■Low lCC.

■Zero bounce in flow-through mode.

■Control inputs compatible with TTL level.

Ordering Code:

Order Number	Package Number	Package Description
FST3245WM	M20B	20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
FST3245QSC	MQA20	20-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150 Wide
FST3245MTC	MTC20	20-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide

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

Logic Diagram

Connection Diagram

Pin Descriptions						Truth Table
	Pin Name				Description		Input OE			Function
					Bus Switch Enable
		OE					L			Connect
		A			Bus A
							H			Disconnect
		B			Bus B

Switch Bus Octal FST3245

© 1999 Fairchild Semiconductor Corporation

DS500020

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FST3245

Absolute Maximum Ratings(Note 1)				Recommended Operating
Supply Voltage (VCC)		−0.5V to +7.0V		Conditions (Note 3)
DC Switch Voltage (VS)		−0.5V to +7.0V		Power Supply Operating (VCC)					4.0V to 5.5V
DC Input Voltage (VIN) (Note 2)		−0.5V to +7.0V		Input Voltage (VIN)					0V to 5.5V
DC Input Diode Current (lIK) VIN < 0V			−50mA	Output Voltage (VOUT)					0V to 5.5V
DC Output (IOUT) Sink Current			128mA	Input Rise and Fall Time (tr, tf)
DC VCC/GND Current (ICC/IGND)		+/− 100mA		Switch Control Input					0nS/V to 5nS/V
Storage Temperature Range (TSTG)		−65°C to +150 °C		Switch I/O					0nS/V to DC
				Free Air Operating Temperature (TA)					−40 °C to +85 °C
				Note 1: The Absolute Maximum Ratings are those values beyond which
				the safety of the device cannot be guaranteed. The device should not be
				operated at these limits. The parametric values defined in the Electrical
				Characteristics tables are not guaranteed at the absolute maximum rating.
				The “Recommended Operating Conditions” table will define the conditions
				for actual device operation.
				Note 2: The input and output negative voltage ratings may be exceeded if
				the input and output diode current ratings are observed.
				Note 3: Unused control inputs must be held HIGH or LOW. They may not
				float.
DC Electrical Characteristics
		VCC	TA = −40 °C to +85 °C
Symbol	Parameter						Units	Conditions
		(V)	Min	Typ	Max
				(Note 4)
VIK	Clamp Diode Voltage	4.5			−1.2		V	IIN = −18 mA
VIH	HIGH Level Input Voltage	4.0–5.5	2.0				V
VIL	LOW Level Input Voltage	4.0–5.5			0.8		V
II	Input Leakage Current	5.5			±1.0		μA	0≤ VIN ≤ 5.5V
IOZ	OFF-STATE Leakage Current	5.5			±1.0		μA	0 ≤A, B ≤ VCC
RON	Switch On Resistance	4.5		4	7		Ω	VIN = 0V, IIN = 64 mA
	(Note 5)	4.5		4	7		Ω	VIN = 0V, IIN = 30 mA
		4.5		8	15		Ω	VIN = 2.4V, IIN = 15 mA
		4.0		11	20		Ω	VIN = 2.4V, IIN = 15 mA
ICC	Quiescent Supply Current	5.5			3		μA	VIN = VCC or GND, IOUT = 0
ICC	Increase in ICC per Input	5.5			2.5		mA	One input at 3.4V
								Other inputs at VCC or GND
Note 4: Typical	values are at VCC = 5.0V and TA = +	25°C

Note 5: Measured by the voltage drop between A and B pins at the indicated current through the switch. On resistance is determined by the lower of the voltages on the two (A or B) pins.

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