FAIRCHILD FSTU16245

Revised April 2001
FSTU16245
16-Bit Bus Switch with −2V Undershoot Protection
General Description
Features
The Fairchild Switch FSTU16245 provides 16-bits of highspeed CMOS TTL-compatible bus switching. The low On
Resistance of the switch allows inputs to be connected to
outputs without adding propagation delay or generating
additional ground bounce noise.
■ Undershoot hardened to −2V (A and B Ports)
The device is organized as a 16-bit switch. There are two
8-bit switches with separate output enable inputs. When
OE is LOW, the switch is ON and Port a is connected to
Port B. When OE is HIGH, the switch is OFF and a high
impedance state exists between the A and B Ports. The A
and B Ports are protected against undershoot to support
an extended range to 2.0V below ground. Fairchild’s integrated Undershoot Hardened Circuit (UHC) senses
undershoot at the I/O and responds by preventing voltage
differentials from developing and turning the switch on.
When OE is HIGH, the switch is OPEN and a high-impedance state exists between the two ports.
■ Zero bounce in flow-through mode.
■ 4Ω switch connection between two ports.
■ Minimal propagation delay through the switch.
■ Low lCC.
■ Control inputs compatible with TTL level.
■ See Application Note AN-5008 for details
Ordering Code:
Order Number
FSTU16245MTD
Package Number
Package Description
MTD48
48-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 6.1mm Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram
Pin Descriptions
Pin Name
Description
OEn
Output Enable Input (Active LOW)
1An, 2An, 3An, 4An
Bus A
1Bn, 2Bn, 3Bn, 4Bn
Bus B
NC
No Internal Connection
UHC is a trademark of Fairchild Semiconductor Corporation.
© 2001 Fairchild Semiconductor Corporation
DS500432
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FSTU16245 16-Bit Bus Switch with −2V Undershoot Protection
April 2001
FSTU16245
Logic Diagram
Truth Table
Inputs
OEx
A, B
L
A Port = B Port
H
Z
H = HIGH Voltage Level
L = LOW Voltage Level
Z = High Impedance
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Outputs
Recommended Operating
Conditions (Note 4)
Supply Voltage (VCC)
−0.5V to +7.0V
DC Switch Voltage (VS) (Note 2)
−2.0V to +7.0V
Power Supply Operating (VCC)
DC Input Voltage (VIN) (Note 3)
−0.5V to +7.0V
Input Voltage (VIN)
0V to 5.5V
0V to 5.5V
DC Input Diode Current (lIK) VIN<0V
−50mA
Output Voltage (VOUT)
DC Output Current (IOUT)
128mA
Input Rise and Fall Time (tr, tf)
±100mA
DC VCC/GND Current (ICC/IGND)
Storage Temperature Range (TSTG)
4.0V to 5.5V
Switch Control Input
−65°C to +150 °C
0nS/V to 5nS/V
Switch I/O
0nS/V to DC
-40 °C to +85 °C
Free Air Operating Temperature (TA)
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: VS is the voltage observed/applied at either the A or B Ports across
the switch.
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
Parameter
VIK
Clamp Diode Voltage
VCC
(V)
Typ
(Note 5)
Min
4.5
Max
Units
−1.2
V
VIH
HIGH Level Input Voltage
4.0–5.5
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
0
10
µA
VIN = 5.5V
±1.0
µA
0 ≤ A, B ≤ VCC
7
Ω
VIN = 0V, IIN = 64 mA
VIN = 0V, IIN = 30 mA
IOZ
OFF-STATE Leakage Current
5.5
RON
Switch On Resistance
4.5
(Note 6)
2.0
Conditions
IIN = −18mA
V
4
4.5
4
7
Ω
4.5
8
14
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
VIKU
Voltage Undershoot
5.5
−2.0
V
Other inputs at VCC or GND
0.0 mA ≥ IIN ≥ −50 mA
OE = 5.5V
Note 5: Typical values are at VCC = 5.0V and TA = +25°C
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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FSTU16245
Absolute Maximum Ratings(Note 1)
FSTU16245
AC Electrical Characteristics
TA = −40 °C to +85 °C,
Symbol
Parameter
CL = 50pF, RU = RD = 500Ω
VCC = 4.5 – 5.5V
Min
tPHL,tPLH
Prop Delay Bus-to-Bus (Note 7)
tPZH, tPZL
Output Enable Time
1.0
VCC = 4.0V
Max
Min
Units
Figure
Conditions
Number
Max
0.25
0.25
ns
6.5
6.9
ns
VI = OPEN
Figures
2, 3
VI = 7V for tPZL
Figures
2, 3
VI = OPEN for tPZH
tPHZ, tPLZ
Output Disable Time
1.0
6.1
6.5
ns
VI = 7V for tPLZ
Figures
2, 3
VI = OPEN for tPHZ
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 source (zero output impedance).
Capacitance
Symbol
(Note 8)
Parameter
Typ
Max
Units
Conditions
CIN
Control Pin Input Capacitance
3
pF
VCC = 5.0V, VIN = 0V
CI/O
Input/Output Capacitance “OFF State”
6
pF
VCC, OE = 5.0V, VIN = 0V
Note 8: TA = +25°C, f = 1 MHz, Capacitance is characterized but not tested.
Undershoot Characteristic (Note 9)
Symbol
VOUTU
Parameter
Output Voltage During Undershoot
Min
Typ
2.5
VOH - 0.3
Max
Units
Conditions
V
Figure 1
Note 9: This test is intended to characterize the device’s protective capabilities by maintaining output signal integrity during an input transient voltage
undershoot event.
FIGURE 1.
Device Test Conditions
Parameter
Value
VIN
see Waveform
V
R1 = R2
100K
Ω
VTRI
11.0
V
VCC
5.5
V
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Transient
Input Voltage (VIN) Waveform
Units
4
FSTU16245
AC Loading and Waveforms
Note: Input driven by 50Ω source terminated in 50Ω
Note: C L includes load and stray capacitance
Note: Input PRR = 1.0 MHz, tW = 500 ns
FIGURE 2. AC Test Circuit
FIGURE 3. AC Waveforms
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FSTU16245 16-Bit Bus Switch with −2V Undershoot Protection
Physical Dimensions inches (millimeters) unless otherwise noted
48-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 6.1mm Wide
Package Number MTD48
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.
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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:
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.
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.
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