5Ω bi-directional switches connect inputs to outputs
Ω
Pin compatibility with QS3245
250ps propagation delay
Undershoot Clamp Diodes on all switch and control Inputs
LVTTL-compatible control Inputs
Available in SOIC and QSOP packages
DESCRIPTION:
APPLICATIONS:
• 3.3V to 2.5V voltage translation
• 2.5V to 1.8V voltage translation
• PCI bus isolation hot swap
The QS3V245 is an 8-bit high speed bus switch controlled by LVTTL-
compatible active low enable signal. When closed, the switches exhibit near
zero propagation delay without generating additional ground bounce or
switching noise.
The QS3V245 is specially designed for direct interface between 3.3V and
2.5V devices without any external components. When operating from a 3.3V
supply, the logic high level at the switch output is clamped to 2.5V when the
switch input signal exceeds 2.5V. This device can be used for switching 2.5V
buses without signal attenuation. The ON resistance at 3.3V V
CC
is less than
5Ω typical, providing near zero propagation delay through the switch.
Absence of DC path from switch I/O pins to V
CC
or ground makes QS3V245
an ideal device for hot swapping applications.
The QS3V245 is characterized for operation from -40°C to +85°C.
FUNCTIONAL BLOCK DIAGRAM
2
A0
3
A1
4
A2
5
A3
6
A4
7
A5
8
A6
9
A7
OE
19
B0
18
B1
17
B2
16
B3
15
B4
14
B5
13
B6
12
B7
11
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
INDUSTRIAL TEMPERATURE RANGE
1
c
2000 Integrated Device Technology, Inc.
NOVEMBER 2000
DSC-5512/1
IDTQS3V245
3.3V HIGH SPEED BUS SWITCH
INDUSTRIAL TEMPERATURE RANGE
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
(1)
Symbol
V
TERM
(2)
V
S
Description
Supply Voltage to Ground
DC Switch Voltage
DC Input Voltage
AC Input Voltage (pulse width
≤20ns)
DC Output Current (max. sink current/pin)
Maximum Power Dissipation
T
STG
Storage Temperature
Max
–0.5 to +4.6
–0.5 to +4.6
–0.5 to +4.6
–3
120
0.5
–65 to +150
Unit
V
V
V
V
mA
W
°C
NC
A0
A1
A2
A3
A4
A5
A6
A7
GND
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
V
CC
OE
B0
B1
B2
B3
B4
B5
B6
B7
V
IN
V
AC
I
OUT
NOTES:
1. Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause
permanent damage to the device. This is a stress rating only and functional operation
of the device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect reliability.
2. V
CC
terminals.
CAPACITANCE
(T
A
= +25°C, f = 1MHz, V
IN
= 0V, V
OUT
= 0V)
Symbol
C
IN
C
I/O
Parameter
(1)
Control Inputs
Quickswitch Channels (Switch OFF)
Typ.
4
5
Max.
6
7
Unit
pF
pF
SOIC/ QSOP
TOP VIEW
NOTE:
1. As applicable to the device type.
PIN DESCRIPTION
Pin Names
OE
Ax
Bx
Output Enable
Data I/Os
Data I/Os
Description
FUNCTION TABLE
(1)
OE
H
L
NOTE:
1. H = HIGH Voltage Level
L = LOW Voltage Level
Outputs
Disconnected
Ax = Bx
2
IDTQS3V245
3.3V HIGH SPEED BUS SWITCH
INDUSTRIAL TEMPERATURE RANGE
DC ELECTRICAL CHARACTERISTICS OVER OPERATING RANGE
Following Conditions Apply Unless Otherwise Specified:
Industrial: T
A
= –40°C to +85°C, V
CC
= 3.3V ±0.3V
Symbol
V
IH
V
IL
I
IN
I
OZ
R
ON
Parameter
Input HIGH Voltage
Input LOW Voltage
Input Leakage Current (Control Inputs)
Off-State Current (Hi-Z)
Switch ON Resistance
Test Conditions
Guaranteed Logic HIGH for Control Inputs
Guaranteed Logic LOW for Control Inputs
0V
≤
V
IN
≤
V
CC
0V
≤
V
OUT
≤
V
CC
, Switches OFF
V
CC
= Min., V
IN
= 0V, I
ON
= 8mA
V
CC
= Min., V
IN
= 1.7V, I
ON
= 8mA
V
CC
= 2.3V, V
IN
= 0V, I
ON
= 8mA
V
CC
= 2.3V, V
IN
= 1.3V, I
ON
= 8mA
V
P
Pass Voltage
(2)
V
IN
= V
CC
= 3.3V, I
OUT
= -5µA
V
IN
= V
CC
= 2.5V, I
OUT
= -5µA
NOTES:
1. Typical values are at V
CC
= 3.3V and T
A
= 25°C.
2. Pass voltage is guaranteed, but not production tested.
Min.
2
—
—
—
—
—
—
—
2.3
—
Typ.
(1)
Max.
—
—
—
0.001
5
15
7
25
2.7
1.8
—
0.8
1
1
7
20
—
—
2.9
—
Unit
V
V
µA
µA
Ω
V
TYPICAL ON RESISTANCE vs V
IN
AT V
CC
= 3.3V
16
14
12
10
R
ON
(ohms)
8
6
4
2
0
0
0.5
1
1.5
2
2.5
V
IN
(Volts)
3
IDTQS3V245
3.3V HIGH SPEED BUS SWITCH
INDUSTRIAL TEMPERATURE RANGE
POWER SUPPLY CHARACTERISTICS
T
A
= –40°C to +85°C, V
CC
= 3.3V ±0.3V
Symbol
I
CCQ
∆I
CC
I
CCD
Parameter
Quiescent Power Supply Current
Power Supply Current
(2)
per Input HIGH
Dynamic Power Supply Current per MHz
(3)
Test Conditions
(1)
V
CC
= Max., V
IN
= GND or V
CC
, f = 0
V
CC
= Max., V
IN
= 3V or V
CC
, f = 0 per Control Input
V
CC
= 3.3V, A and B Pins Open, Control Input Toggling
@ 50% Duty Cycle
NOTES:
1. For conditions shown as Min. or Max., use the appropriate values specified under DC Electrical Characteristics.
2. Per TTL driven input (V
IN
= 3V, control inputs only). A and B pins do not contribute to Icc.
3. This current applies to the control inputs only and represents the current required to switch internal capacitance at the specified frequency. The A and B inputs generate no significant
AC or DC currents as they transition. This parameter is guaranteed but not production tested.
Min.
—
—
—
Max.
3
30
0.15
Unit
µA
µA
mA/MHz
SWITCHING CHARACTERISTICS OVER OPERATING RANGE
(1)
T
A
= -40°C to +85°C
Symbol
t
PLH
t
PHL
t
PZL
t
PZH
t
PLZ
t
PHZ
Parameter
Data Propagation Delay
(2,3)
Ax to/from Bx
Switch Turn-On Delay
OE
to Ax/Bx
Switch Turn-Off Delay
(2)
OE
to Ax/Bx
0.5
4
ns
0.5
6.5
ns
Min.
Typ
.
Max.
0.25
Unit
ns
NOTES:
1. See TEST CIRCUITS AND WAVEFORMS. Minimums guaranteed but not production tested
2. This parameter is guaranteed but not production tested.
3. The bus switch contributes no propagation delay other than the RC delay of the ON resistance of the switch and the load capacitance. The time constant for the switch alone
is of the order of 0.25ns for C
L
= 30pF. Since this time constant is much smaller than the rise and fall times of typical driving signals, it adds very little propagation delay to the
system. Propagation delay of the bus switch, when used in a system, is determined by the driving circuit on the driving side of the switch and its interaction with the load on
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