Fairchild FST32245 service manual
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Preliminary
June 2001
Revised June 2001
FST32245
Octal Bus Switch wi th 25
Ω Series Resistor in Outputs
(Preliminary)
General Description
The Fairchild Switch FST32245 provides 8-bits of highspeed CMOS TTL-comp atible bus switch ing in a standa rd
’245 pin-out. The low On Resist ance of the switch allows
inputs to be connect ed to out puts wit hout adding prop agation delay or generating additional ground bounce noise.
The device is organized as an 8-bit swi tch. When OE
LOW, the switch is ON and Port A is connecte d to P ort B.
When OE
ance state exists between the two ports.
The FST32245 has an equiva lent 25
reduce signal-reflection noise, eliminating the need for
external terminating resistors.
is HIGH, the switch is OPEN and a high-imped-
Ω series resistors to
Ordering Code:
Order Number Package Number Package Description
FST32245WM M20B 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" Wide
FST32245QSC MQA20 20-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150" Wide
FST32245MTC MTC20 20-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
Devices also availab l e in Tape and Reel. Specify by appending th e s uffix let t er “X” to the ordering code.
Features
■ 25Ω switch connection between two ports
■ Minimal propagation delay through the switch
■ Low l
CC
■ Zero bounce in flow-through mode
■ Control inputs compatible with TTL level
is
FST32245 Octal Bus Switch with 25
Ω
Series Resistor in Outputs (Preliminary)
Logic Diagram
Connection Diagram
Pin Descriptions
Pin Name Description
OE
ABus A
BBus B
NC No Connect
© 2001 Fairchild Semiconductor Corporation DS500473 www.fairchildsemi.com
Bus Switch Enable
Truth Table
Input OE Function
L Connect
H Disconnect
Preliminary
Absolute Maximum Ratings(Note 1) Recommended Operating
Supply Voltage (VCC) −0.5V to +7.0V
DC Switch Voltage (V
FST32245
DC Input Voltage (V
DC Input Diode Current (l
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 values beyond which
the safety of the d evice cannot be guaranteed. The device sh ould not be
operated at these limit s. The parametric values defin ed in the Electrical
Characteristics tables are not guaranteed at the absolute maximum rating.
The “Recomme nded O peratin g Cond itions ” table will defin e the condition s
for actual device operation.
Note 2: The input and output ne gative vo ltage ra tings may be excee ded 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.
(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
= −40 °C to +85 °C
T
V
Symbol Parameter
V
IK
V
IH
V
IL
I
I
I
OZ
R
ON
I
CC
∆ I
CC
Note 4: Typi c al values are at VCC = 5.0V and TA = +25°C
Note 5: Measured by the volta ge drop between A an d B pins at the indicated c urrent through the switch. On Resistance is determined by the lower of the
voltages on the two (A or B) pins.
Clamp Diode Voltage 4.5 −1.2 V IIN = −18 mA
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 µA0 ≤ VIN ≤ 5.5V
OFF-STATE Leakage Current 5.5 ±1.0 µA0 ≤ A, B ≤ V
Switch On Resistance 4.5 20 26 38 Ω VIN = 0V, IIN = 64 mA
(Note 5) 4.5 20 27 40 Ω V
Quiescent Supply Current 5.5 3 µAVIN = VCC or GND, I
Increase in I
per Input 5.5 2.5 mA One input at 3.4V
CC
CC
(V)
010µAV
4.5 202848Ω VIN = 2.4V, IIN = 15 mA
4.0 203048Ω V
A
Min Typ
(Note 4)
Units Conditions
Max
Other inputs at V
= 5.5V
IN
CC
= 0V, IIN = 30 mA
IN
= 2.4V, IIN = 15 mA
IN
or GND
CC
OUT
= 0
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