FST3244 8-Bit Bus Switch
June 1997 Revised January 2005
FST3244 8-Bit Bus Switch
General Description
The Fairchild Switch FST3244 provides 8-bits of highspeed CMOS TTL-compatible bus switching in a standard ’244 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 two 4-bit switches with separate OE inputs. 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-impedance state exists between the two ports.
Features ■ 4: 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 FST3244WM FST3244QSC FST3244MTC FST3244MTCX_NL (Note 1) Package Number M20B MQA20 MTC20 MTC20 Package Description 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" Wide 20-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150" Wide 20-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide Pb-Free 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. Note 1: “_NL” indicates Pb-Free package (per JEDEC J-STD-020B). Device available in Tape and Reel only.
Logic Diagram
Connection Diagram
Truth Table
Inputs OE1 OE2 L H L H Inputs/Outputs 1A, 1B 1A 1A Z Z 1B 1B 2A Z 2A, 2B 2A Z 2B 2B
Pin Descriptions
Pin Name OE1, OE2 1A, 2A 1B, 2B Description Bus Switch Enable Bus A Bus B DS500021
L L H H
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FST3244
Absolute Maximum Ratings(Note 2) Supply Voltage (VCC) 0.5V to 7.0V 0.5V to 7.0V DC Switch Voltage (VS) DC Input Voltage (VIN ) (Note 3) 0.5V to 7.0V 50mA DC Input Diode Current (lIK) VIN0V
DC Output (IOUT ) Sink Current DC VCC/GND Current (ICC/IGND) Storage Temperature Range (TSTG)
Recommended Operating Conditions (Note 4)
Power Supply Operating (VCC) Input Voltage (VIN) Output Voltage (VOUT) Input Rise and Fall Time (tr, tf) Switch Control Input Switch I/O Free Air Operating Temperature (TA) 0nS/V to 5nS/V 0nS/V to DC 4.0V to 5.5V 0V to 5.5V 0V to 5.5V
/ 100mA 65qC to 150 qC
128mA
40 qC to 85 qC
Note 2: 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 tables will define the conditions for actual device operation. Note 3: The input and output negative voltage ratings may be exceeded if the input and output diode current ratings are observed. Note 4: Unused control inputs must be held HIGH or LOW. They may not float.
DC Electrical Characteristics
Symbol VIK VIH VIL II IOZ RON Parameter Clamp Diode Voltage High Level Input Voltage Low Level Input Voltage Input Leakage Current OFF-STATE Leakage Current Switch On Resistance (Note 6) VCC (V) 4.5 4.0–5.5 4.0–5.5 5.5 5.5 4.5 4.5 4.5 4.0 ICC Quiescent Supply Current Increase in ICC per Input
5.0V and T A
TA Min
40 qC to 85 qC
Typ (Note 5) Units Max Conditions IIN
1.2
2.0 0.8
V V V
18mA
r1.0 r1.0
4 4 8 11 7 7 15 20 3 2.5
PA PA : : : : PA
mA
0d VIN d5.5V 0 dA, B dVCC VIN VIN VIN VIN VIN 0V, IIN 0V, IIN 2.4V, IIN 2.4V, IIN 64mA 30mA 15mA 15mA 0
5.5 5.5
25qC
VCC or GND, IOUT
' ICC
One input at 3.4V Other inputs at VCC or GND
Note 5: Typical values are at VCC
Note 6: 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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FST3244
AC Electrical Characteristics
CL Symbol Parameter VCC Min tPHL,tPLH tPZH, tPZL tPHZ, tPLZ Prop Delay Bus to Bus (Note 7) Output Enable Time Output Disable Time 1.0 1.0 TA 40 qC to 85 qC, 50pF, RU RD 500: VCC Min 4.0V Max 0.25 6.1 5.6 ns ns ns VI VI VI 6.2 VI VI OPEN 7V for tPZL OPEN for tPZH 7V for tPLZ OPEN for tPHZ Figures 1, 2 Figures 1, 2 Figures 1, 2 Units Conditions Figure No.
4.5 – 5.5V Max 0.25 5.6
Note 7: This parameter is guaranteed by design but is not tested. The bus switch contributes no propagation delay other than the RC delay of the typical On resistance of the switch and the 50pF load capacitance, when driven by an ideal voltage the source (zero output impedance).
Capacitance
Symbol CIN CI/O
Note 8: TA
(Note 8)
Parameter Typ 3 5 Max Units pF pF VCC 5.0V 5.0V Conditions
Control Pin Input Capacitance Input/Output Capacitance
25qC, f
VCC, OE
1 MHz, Capacitance is characterized but not tested.
AC Loading and Waveforms
Note: Input driven by 50 : source terminated in 50 : Note: C L includes load and stray capacitance Note: Input PRR 1.0 MHz, tW 500 nS
FIGURE 1. AC Test Circuit
FIGURE 2. AC Waveforms
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FST3244
Physical Dimensions inches (millimeters) unless otherwise noted
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" Wide Package Number M20B
20-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150" Wide Package Number MQA20
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FST3244 8-Bit Bus Switch
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
20-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide Package Number MTC20
Technology Description
The Fairchild Switch family derives from and embodies Fairchild’s proven switch technology used for several years in its 74LVX3L384 (FST3384) bus switch product.
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right at any time without notice to change said circuitry and specifications. LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 5 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com
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