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FSTU32X384
20-Bit Low Power Bus Switch
with
−2V Undershoot Protection
FSTU32X384 20-Bit Low Power Bus Switch with
May 2002
Revised June 2002
General Description
The Fairchild Switch FSTU32X384 provides 20 bits of highspeed CMOS TTL-compatib le bus switches. The low On
Resistance of the switch allows inputs to be connected to
outputs without adding propagation delay or generating
additional ground bou nce noise. The device is organ ized
as four 5-bit switches with separate b us enable (OE
nals. When OE
nected to Port B. When OE
and a high-impedance state exists between the two 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
preventing voltage differentials from developing and turning the switch on.
is LOW, the switch is ON and Port A is con-
is HIGH, the switch is OPEN
) senses undershoot at the I/O and responds by
) sig-
Features
■ 4Ω switch connection between two ports
■ Minimal propagation delay through the switch
■ Ultra low power with
■ Zero ground bounce in flow-through mode
■ Control inputs compatible with TTL level
■ See Application Note AN-5008 for details on
FSTU - Undershoot Protected Fairchild Switch Family
< 0.1 µA typical I
CC
Ordering Code:
Order Number
FSTU32X384QSP MQA48A 48-Lead Quarter Size Very Small Outline Package (QVSOP), JEDEC MO-154, 0.150" Wide
Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.
Package
Number
Package Descript ion
Logic Diagram
−
2V Undershoot Protection
UHC is a trademark of Fairchild Semiconductor Corporation.
© 2002 Fairchild Semiconductor Corporation DS500705 www.fairchildsemi.com
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Pin Descriptions
Pin Names Description
FSTU32X384
Truth Table
Inputs Inputs/Outputs
OE
X
ABus A
BBus B
OE
X
LA = B
HZ
Bus Switch Enable
A, B
Connection Diagram
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Absolute Maximum Ratings(Note 1) Recommended Operating
Supply Voltage (VCC) −0.5V to +7.0V
DC Switch Voltage (V
DC Input Voltage (V
DC Input Diode Current (I
DC Output (I
DC V
OUT
/GND Current (ICC/I
CC
Storage Temperature Range (T
) −0.5V to +7.0V
S
) (Note 2) −0.5V to +7.0V
IN
) V
< 0V −50 mA
IK
IN
) Sink Current 128 mA
) ± 100 mA
GND
) −65°C to +150°C
STG
Conditions
Power Supply Operating (V
Input Voltage (V
Output Voltage (V
Input Rise and Fall Time (t
Switch Control Input 0 ns/V to 5 ns/V
Switch I/O 0 ns/V to DC
Free Air Operating Temperature (T
Note 1: The “Absolute Maximum Ratings” are those value s beyond which
the safety of the d evice cannot b e guaranteed . The device sh ould not be
operated at thes e limits. The param etric values define d in the “Electrical
Characteristics” table are not guaranteed at the absolute maximum rat ings.
The “Recomm ended O peratin g Cond itions ” table will defin e the condition s
for actual device operation.
Note 2: The input and output negative voltage ratings may be exceeded if
the input and ou t put diode curre nt ratings are observed.
Note 3: Unused control inputs must be held HIGH or LOW. They may not
float.
(Note 3)
) 4.0V to 5.5V
CC
) 0V to 5.5V
IN
) 0V to 5.5V
OUT
, tf)
r
) −40°C to +85°C
A
DC Electrical Characteristics
V
Symbol Parameter
V
IK
V
IH
V
IL
I
I
I
OZ
R
ON
I
CC
∆ I
CC
V
IKU
Note 4: All typical values are at VCC = 5.0V , TA = 25°C.
Note 5: Measured by voltage drop between A and B pin at indicated current through the switch. On Resistance is determined by the lower of the voltages on
the two (A or B) pins.
Note 6: Per V
Note 7: Per TTL driven input, control pins only.
Clamp Diode Voltage 4.5 −1.2 V IIN= − 18mA
HIGH Level Input Voltage 4.0 - 5.5 2.0 V
LOW Level Input Voltage 4.0 - 5.5 0.8 V
Input Leakage Current 5.5 ±1.0
OFF-STATE Leakage Current 5.5 ±1.0 µA0 ≤ A, B ≤ V
Switch On Resistance 4.5 4 7
(Note 5) 4.5 4 7 V
Quiescent Supply Current (Note 6) 5.5 3 µAVIN = VCC or GND, I
Increase in ICC per Input 5.5 2.5 mA One Input at 3.4V
(Note 7) Other Inputs at V
Voltage Undershoot 5.5 −2.0 V 0.0 mA ≥ IIN ≥ 50 mA
pin.
CC
CC
(V)
010V
4.5 8 15 VIN = 2.4V, IIN = 15 mA
4.0 11 20 V
TA = −40°C to +85°C
Min Typ
(Note 4)
Units Condition
Max
µA
Ω
0 ≤ VIN ≤ 5.5V
= 5.5V
IN
VIN = 0V, IIN = 64 mA
OE = 5.5V
CC
= 0V, IIN = 30 mA
IN
= 2.4V, IIN = 15 mA
IN
CC
= 0
OUT
or GND
FSTU32X384
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AC Electrical Characteristics
= −40°C to +85°C
T
A
C
= 50 pF, RU = RD = 500Ω
Symbol Parameter
FSTU32X384
t
, t
PHL
t
PZH
t
PHZ
Note 8: This parameter is gu arant eed by d esig n b ut n ot tes ted . The bu s sw itch con tribu tes n o p ropag atio n d elay othe r th an th e R C de lay o f th e typ i ca l O n
Resistance of th e s w it c h and the 50pF load capa c i t anc e, when driven by an ideal voltage the sour ce (z ero output impedanc e).
Propagation Delay Bus to Bus
PLH
(Note 8)
, t
Output Enable Time
PZL
, t
PLZ
, OE2 to An, B
OE
1
Output Disable Time
, OE2 to An, B
OE
1
n
n
L
= 4.5 − 5.5V VCC = 4.0V
V
CC
Min Max Min Max
0.25 0.25 ns V
1.0 5.7 6.2 ns
1.5 5.2 5.5 ns
Units Conditions
= OPEN
I
VI = 7V for t
VI = OPEN for t
II = 7V for t
VI = OPEN for t
PZL Figures
PZH
PLZ Figures
PHZ
Capacitance (Note 9)
Symbol Parameter Typ Max Units Conditions
C
IN
C
I/O
Note 9: Capacitance is characterized but not tested.
Control Input Capacitance 3 6 pF VCC = 5.0V
(OFF) Input/Output Capacitance 5 13 pF VCC, OE = 5.0V
Undershoot Characteristic (Note 10)
Symbol Parameter Min Typ Max Units Conditions
V
OUTU
Note 10: This test is intend ed to ch aracte rize the devic e’s protective capabilities by maintaining output signal integrity during an input transient voltage
undershoot event.
Output Voltage During Undershoot 2.5 VOH - 0.3 V Figure 1
Figure
Number
Figures
2, 3
2, 3
2, 3
FIGURE 1.
Device Test Conditions Transient
Parameter Value Units
V
IN
R
= R
1
V
TRI
V
CC
see Waveform V
2
100K Ω
11.0 V
5.5 V
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Input Voltage (V
) Waveform
IN
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AC Loading and Waveforms
Note: Input driven by 50 Ω source terminated in 50 Ω
includes load and stray capacitance
Note: C
L
Note: Input PRR = 1.0 MHz, t
= 500 ns
W
FIGURE 2. AC Test Circuit
FSTU32X384 V
vs. RON (Typ)
IN
FSTU32X384
FIGURE 3. AC Waveforms
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Physical Dimensions inches (millimeters) unless otherwise noted
2V Undershoot Protection
−
FSTU32X384 20-Bit Low Power Bus Switch with
48-Lead Quarter Size Very Small Outline Package (QVSOP), JEDEC MO-154, 0.150" Wide
Package Number MQA48A
Technology Description
The Fairchild Switch family derives from and embodies Fairchild’s proven s witch technol ogy used for several years i n its
74LVX3L384 (FSTU32X384) bus switch product.
Fairchild does not assume any responsibility for use of any circuitr y described, no circuit patent licenses are implied a nd
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 device s or syste ms
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 inju ry to the
user.
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2. A critical component in any compon ent of a l ife supp ort
device or system whose failu re to perform can be reasonably expected to cause the failure of the li fe su pp ort
device or system, or to affect its safety or effectiveness.
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