SCDS140 − OCTOBER 2003
D
D
D
D
D
D
D
5-V/3.3-V CMOS Outputs
Ioff Supports Partial-Power-Down Mode
Operation
Latch-Up Performance Exceeds 100 mA Per
JESD 78, Class II
ESD Performance Tested Per JESD 22
− 2000-V Human-Body Model
(A114-B, Class II)
− 1000-V Charged-Device Model (C101)
Supports Both Digital and Analog
Applications: PCI Interface, Memory
Interleaving, Bus Isolation, Low-Distortion
Signal Gating
RGY PACKAGE
(TOP VIEW)
DB, DBQ, DGV, DW, OR PW PACKAGE
(TOP VIEW)
BIASV
A1
A2
A3
A4
A5
A6
A7
A8
GND
1
20
2
19
3
18
4
17
5
16
6
15
7
14
8
13
9
12
10
11
VCC
OE
B1
B2
B3
B4
B5
B6
B7
B8
A1
A2
A3
A4
A5
A6
A7
A8
VCC
D
(0.8-V, 1.2-V, 1.5-V, 1.8-V, 2.5-V, 3.3-V, 5-V)
D Control Inputs Can be Driven by TTL or
1
20
19 OE
18 B1
2
3
17 B2
16 B3
4
5
15 B4
14 B5
6
7
13 B6
12 B7
8
9
10
11
B8
D
D
D VCC Operating Range From 4 V to 5.5 V
D Data I/Os Support 0 to 5-V Signaling Levels
BIASV
D
A and B Ports Up To −2 V
B-Port Outputs Are Precharged by Bias
Voltage (BIASV) to Minimize Signal
Distortion During Live Insertion and
Hot-Plugging
Supports PCI Hot Plug
Bidirectional Data Flow, With Near-Zero
Propagation Delay
Low ON-State Resistance (ron)
Characteristics (ron = 3 Ω Typical)
Low Input/Output Capacitance Minimizes
Loading and Signal Distortion
(Cio(OFF) = 5.5 pF Typical)
Data and Control Inputs Provide
Undershoot Clamp Diodes
Low Power Consumption
(ICC = 3 µA Max)
GND
D Undershoot Protection for Off-Isolation on
description/ordering information
The SN74CBT6845C is a high-speed TTL-compatible FET bus switch with low ON-state resistance (ron),
allowing for minimal propagation delay. Active Undershoot-Protection Circuitry on the A and B ports of the
SN74CBT6845C provides protection for undershoot up to −2 V by sensing an undershoot event and ensuring
that the switch remains in the proper OFF state. The device also precharges the B port to a user-selectable bias
voltage (BIASV) to minimize live-insertion noise.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright 2003, Texas Instruments Incorporated
!"# $ %&'# "$ (&)*%"# +"#',
+&%#$ %! # $('%%"#$ (' #-' #'!$ '."$ $#&!'#$
$#"+"+ /""#0, +&%# (%'$$1 +'$ # '%'$$"*0 %*&+'
#'$#1 "** (""!'#'$,
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
1
SCDS140 − OCTOBER 2003
description/ordering information (continued)
The SN74CBT6845C is an 8-bit bus switch with a single output-enable (OE) input. When OE is low, the 8-bit
bus switch is ON, and the A port is connected to the B port, allowing bidirectional data flow between ports. When
OE is high, the 8-bit bus switch is OFF, and a high-impedance state exists between the A and B ports. The B
port is precharged to BIASV through the equivalent of a 10-kΩ resistor when OE is high, or if the device is
powered down (VCC = 0 V).
During insertion (or removal) of a card into (or from) an active bus, the card’s output voltage may be close to
GND. When the connector pins make contact, the card’s parasitic capacitance tries to force the bus signal to
GND, creating a possible glitch on the active bus. This glitching effect can be reduced by using a bus switch
with precharged bias voltage (BIASV) of the bus switch equal to the input threshold voltage level of the receivers
on the active bus. This method will ensure that any glitch produced by insertion (or removal) of the card will not
cross the input threshold region of the receivers on the active bus, minimizing the effects of live-insertion noise.
This device is fully specified for partial-power-down applications using Ioff. The Ioff feature ensures that
damaging current will not backflow through the device when it is powered down. The device has isolation during
power off.
To ensure the high-impedance state during power up or power down, OE should be tied to VCC through a pullup
resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
ORDERING INFORMATION
QFN − RGY
SOIC − DW
−40°C
85°C
−40
C to 85
C
ORDERABLE
PART NUMBER
PACKAGE†
TA
SSOP − DB
SSOP (QSOP) − DBQ
TSSOP − PW
Tape and reel
SN74CBT6845CRGYR
Tube
SN74CBT6845CDW
Tape and reel
SN74CBT6845CDWR
Tube
SN74CBT6845CDB
Tape and reel
SN74CBT6845CDBR
Tape and reel
SN74CBT6845CDBQR
Tube
SN74CBT6845CPW
Tape and reel
SN74CBT6845CPWR
TOP-SIDE
MARKING
CT6845C
CBT6845C
CT6845C
CBT6845C
CT6845C
TVSOP − DGV
Tape and reel
SN74CBT6845CDGVR
CT6845C
† Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are
available at www.ti.com/sc/package.
FUNCTION TABLE
2
INPUT
OE
INPUT/OUTPUT
A
FUNCTION
L
B
A port = B port
H
Z
Disconnect
B port = BIASV
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
SCDS140 − OCTOBER 2003
logic diagram (positive logic)
1
18
2
SW
A1
A8
BIASV
9
B1
11
SW
B8
48
OE
simplified schematic, each FET switch (SW)
A
B
Undershoot
Protection Circuit
EN†
† EN is the internal enable signal applied to the switch.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
3
SCDS140 − OCTOBER 2003
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)†
Supply voltage range, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.5 V to 7 V
Bias supply voltage range, BIASV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.5 V to 7 V
Control input voltage range, VIN (see Notes 1 and 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.5 V to 7 V
Switch I/O voltage range, VI/O (see Notes 1, 2, and 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.5 V to 7 V
Control input clamp current, IIK (VIN < 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −50 mA
I/O port clamp current, II/OK (VI/O < 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −50 mA
ON-state switch current, II/O (see Note 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±128 mA
Continuous current through VCC or GND terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±100 mA
Package thermal impedance, θJA (see Note 5): DB package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70°C/W
(see Note 5): DBQ package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68°C/W
(see Note 5): DGV package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92°C/W
(see Note 5): DW package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58°C/W
(see Note 5): PW package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83°C/W
(see Note 6): RGY package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37°C/W
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to 150°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTES: 1. All voltages are with respect to ground unless otherwise specified.
2. The input and output voltage ratings may be exceeded if the input and output clamp-current ratings are observed.
3. VI and VO are used to denote specific conditions for VI/O.
4. II and IO are used to denote specific conditions for II/O.
5. The package thermal impedance is calculated in accordance with JESD 51-7.
6. The package thermal impedance is calculated in accordance with JESD 51-5.
recommended operating conditions (see Note 7)
MIN
MAX
UNIT
VCC
BIASV
Supply voltage
4
5.5
V
Bias supply voltage
0
V
VIH
VIL
High-level control input voltage
2
VCC
5.5
Low-level control input voltage
0
0.8
V
VI/O
TA
Data input/output voltage
0
5.5
V
−40
85
°C
Operating free-air temperature
V
NOTE 7: All unused control inputs of the device must be held at VCC or GND to ensure proper device operation. Refer to the TI application report,
Implications of Slow or Floating CMOS Inputs, literature number SCBA004. BIASV is a supply voltage, not a control input.
4
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
SCDS140 − OCTOBER 2003
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
VIK
Control inputs
VCC = 4.5 V,
VIKU
Data inputs
VCC = 5 V,
VO(USP)‡
IIN = −18 mA
0 mA > II ≥ −50 mA,
VIN = VCC or GND,
MIN
Switch OFF
VCC = BIASV = 5 V,
II = −10 mA,
VIN = VCC or GND,
Switch OFF
B port
VCC = 0 V,
BIASV = Vx,
IO = 0
IIN
Control inputs
VCC = 5.5 V,
VIN = VCC or GND
BIASV = 2.4 V,
VO = 0,
Switch OFF,
VIN = VCC or GND
VO = 0 to 5.5 V,
VI = 0,
Switch OFF,
VIN = VCC or GND
VO = 0 to 5.5 V,
II/O = 0,
VIN = VCC or GND,
VI = 0
Other inputs at VCC or GND
B port
VCC = 4.5 V,
IOZ§
VCC = 5.5 V,
Ioff
VCC = 0,
ICC
VCC = 5.5 V,
∆ICC¶
Cin
Control inputs
VCC = 5.5 V,
VIN = 3 V or 0
One input at 3.4 V,
Control inputs
Cio(OFF)
A port
VI/O = 3 V or 0,
Switch OFF,
VI/O = 3 V or 0,
VCC = 4 V,
TYP at VCC = 4 V
Cio(ON)
ron#
VCC = 4.5 V
MAX
UNIT
−1.8
V
−2
V
3
VO
IO
TYP†
V
Vx −0.1
Vx
V
±1
µA
0.25
mA
±10
µA
10
µA
3
µA
2.5
mA
Switch ON or OFF
4
pF
VIN = VCC or GND
5.5
pF
Switch ON,
VIN = VCC or GND
13.5
pF
VI = 2.4 V,
IO = −15 mA
8
12
IO = 64 mA
IO = 30 mA
3
6
VI = 0
3
6
Ω
VI = 2.4 V,
IO = −15 mA
5
10
VIN and IIN refer to control inputs. VI, VO, II, and IO refer to data pins.
† All typical values are at VCC = 5 V (unless otherwise noted), TA = 25°C.
‡ VO(USP) = A-port undershoot static protection.
§ For I/O ports, the parameter IOZ includes the input leakage current.
¶ This is the increase in supply current for each input that is at the specified voltage level, rather than VCC or GND.
# Measured by the voltage drop between the A and B terminals at the indicated current through the switch. ON-state resistance is determined by
the lower of the voltages of the two (A or B) terminals.
switching characteristics over recommended operating free-air temperature range (unless
otherwise noted) (see Figure 1)
PARAMETER
TEST
CONDITIONS
tpd||
tPZH
BIASV = GND
tPZL
BIASV = 3 V
tPHZ
BIASV = GND
tPLZ
BIASV = 3 V
FROM
(INPUT)
TO
(OUTPUT)
A or B
B or A
OE
A or B
OE
A or B
VCC = 4 V
VCC = 5 V
± 0.5 V
MIN
MIN
MAX
0.24
UNIT
MAX
0.15
5.2
1.5
4.8
5.2
1.5
4.8
4.9
1.5
5.3
4.9
1.5
5.3
ns
ns
ns
|| The propagation delay is the calculated RC time constant of the typical ON-state resistance of the switch and the specified load capacitance,
when driven by an ideal voltage source (zero output impedance).
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
5
SCDS140 − OCTOBER 2003
PARAMETER MEASUREMENT INFORMATION
VCC
Input Generator
VIN
50 Ω
50 Ω
VG1
TEST CIRCUIT
DUT
7V
Input Generator
VI
S1
RL
VO
GND
50 Ω
50 Ω
VG2
CL
(see Note A)
RL
TEST
VCC
S1
RL
VI
CL
tpd(s)
5 V ± 0.5 V
4V
Open
Open
500 Ω
500 Ω
VCC or GND
VCC or GND
50 pF
50 pF
tPLZ/tPZL
5 V ± 0.5 V
4V
7V
7V
500 Ω
500 Ω
GND
GND
50 pF
50 pF
0.3 V
0.3 V
tPHZ/tPZH
5 V ± 0.5 V
4V
Open
Open
500 Ω
500 Ω
VCC
VCC
50 pF
50 pF
0.3 V
0.3 V
Output
Control
(VIN)
V∆
3V
1.5 V
3V
1.5 V
1.5 V
0V
tPLH
VOH
Output
1.5 V
Output
Waveform 1
S1 at 7 V
(see Note B)
tPLZ
3.5 V
1.5 V
tPZH
tPHL
1.5 V
VOL
Output
Waveform 2
S1 at Open
(see Note B)
VOLTAGE WAVEFORMS
PROPAGATION DELAY TIMES (tpd(s))
1.5 V
0V
tPZL
Output
Control
(VIN)
Open
VOL + V∆
VOL
tPHZ
1.5 V
VOH − V∆
VOH
0V
VOLTAGE WAVEFORMS
ENABLE AND DISABLE TIMES
NOTES: A. CL includes probe and jig capacitance.
B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control.
Waveform 2 is for an output with internal conditions such that the output is high except when disabled by the output control.
C. All input pulses are supplied by generators having the following characteristics: PRR ≤ 10 MHz, ZO = 50 Ω, tr ≤ 2.5 ns, tf ≤ 2.5 ns.
D. The outputs are measured one at a time with one transition per measurement.
E. tPLZ and tPHZ are the same as tdis.
F. tPZL and tPZH are the same as ten.
G. tPLH and tPHL are the same as tpd(s). The tpd propagation delay is the calculated RC time constant of the typical ON-state
resistance of the switch and the specified load capacitance, when driven by an ideal voltage source (zero output impedance).
H. All parameters and waveforms are not applicable to all devices.
Figure 1. Test Circuit and Voltage Waveforms
6
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
SN74CBT6845CPW
ACTIVE
TSSOP
PW
20
70
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
CT6845C
SN74CBT6845CPWR
ACTIVE
TSSOP
PW
20
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
CT6845C
SN74CBT6845CRGYR
ACTIVE
VQFN
RGY
20
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
CT6845C
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of