SN74HCS126-Q1
SN74HCS126-Q1
SCLS753A – JUNE 2020 – REVISED
MARCH 2021
SCLS753A – JUNE 2020 – REVISED MARCH 2021
www.ti.com
SN74HCS126-Q1 Automotive Quadruple Buffer with 3-State Outputs and SchmittTrigger Inputs
1 Features
2 Applications
•
•
•
•
•
This device contains four independent buffer with 3state outputs and Schmitt-trigger inputs. Each gate
performs the Boolean function Y = A in positive logic.
The outputs can be put into a Hi-Z state by applying a
Low on the OE pin
Device Information
PART NUMBER
PACKAGE(1)
BODY SIZE (NOM)
SN74HCS126PW-Q1
TSSOP (14)
5.00 mm × 4.40 mm
SN74HCS126D-Q1
SOIC (14)
8.70 mm × 3.90 mm
(1)
Response
Waveforms
Voltage
Output
Current
Voltage
Current
Output
Input Voltage
Time
Time
Voltage
Input Voltage
Output
Schmitt-trigger
CMOS Input
Time
Time
Current
Response
Waveforms
Supply Current
Standard
CMOS Input
Supply Current
Input Voltage
Supports Slow Inputs
Input
Voltage
Noise Rejection
Input
Voltage
Input Voltage
Waveforms
Input
Voltage
Low Power
For all available packages, see the orderable addendum at
the end of the data sheet.
Time
Voltage
•
3 Description
Output
•
Enable or disable a digital signal
Controlling an indicator LED
Debounce a switch
Eliminate slow or noisy input signals
Current
•
•
AEC-Q100 Qualified for automotive applications:
– Device temperature grade 1:
–40°C to +125°C, TA
– Device HBM ESD Classification Level 2
– Device CDM ESD Classifcation Level C6
Wide operating voltage range: 2 V to 6 V
Schmitt-trigger inputs allow for slow or noisy input
signals
Low power consumption
– Typical ICC of 100 nA
– Typical input leakage current of ±100 nA
±7.8-mA output drive at 6 V
Time
Benefits of Schmitt-trigger inputs
An©IMPORTANT
NOTICEIncorporated
at the end of this data sheet addresses availability, warranty, changes, use in
safety-critical
applications,
Copyright
2021 Texas Instruments
Submit
Document
Feedback
intellectual property matters and other important disclaimers. PRODUCTION DATA.
Product Folder Links: SN74HCS126-Q1
1
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
Table of Contents
1 Features............................................................................1
2 Applications..................................................................... 1
3 Description.......................................................................1
4 Revision History.............................................................. 2
5 Pin Configuration and Functions...................................3
Pin Functions.................................................................... 3
6 Specifications.................................................................. 4
6.1 Absolute Maximum Ratings ....................................... 4
6.2 ESD Ratings .............................................................. 4
6.3 Recommended Operating Conditions ........................4
6.4 Thermal Information ...................................................4
6.5 Electrical Characteristics ............................................5
6.6 Switching Characteristics ...........................................5
6.7 Operating Characteristics .......................................... 6
6.8 Typical Characteristics................................................ 6
7 Parameter Measurement Information............................ 7
8 Detailed Description........................................................8
8.1 Overview..................................................................... 8
8.2 Functional Block Diagram........................................... 8
8.3 Feature Description.....................................................8
8.4 Device Functional Modes............................................9
9 Application and Implementation.................................. 10
9.1 Application Information............................................. 10
9.2 Typical Application.................................................... 10
10 Power Supply Recommendations..............................13
11 Layout........................................................................... 13
11.1 Layout Guidelines................................................... 13
11.2 Layout Example...................................................... 13
12 Device and Documentation Support..........................14
12.1 Documentation Support.......................................... 14
12.2 Receiving Notification of Documentation Updates..14
12.3 Support Resources................................................. 14
12.4 Trademarks............................................................. 14
12.5 Electrostatic Discharge Caution..............................14
12.6 Glossary..................................................................14
13 Mechanical, Packaging, and Orderable
Information.................................................................... 15
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision * (June 2020) to Revision A (March 2021)
Page
• Changed the unit of II from µA to nA...................................................................................................................5
2
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
5 Pin Configuration and Functions
VCC
1OE
1A
4OE
1Y
4A
2OE
4Y
2A
3OE
2Y
3A
GND
3Y
Figure 5-1. PW or D Package 14-Pin TSSOP or SOIC Top View
Pin Functions
PIN
NAME
NO.
1OE
1
1A
1Y
I/O
DESCRIPTION
Input
Channel 1, Output Enable, Active High
2
Input
Channel 1, Input A
3
Output
2OE
4
Input
Channel 2, Output Enable, Active High
2A
5
Input
Channel 2, Input A
2Y
6
Output
GND
7
—
3Y
8
Output
3A
9
Input
Channel 3, Input A
3OE
10
Input
Channel 3, Output Enable, Active High
4Y
11
Output
4A
12
Input
Channel 4, Input A
4OE
13
Input
Channel 4, Output Enable, Active High
VCC
14
—
Channel 1, Output Y
Channel 2, Output Y
Ground
Channel 3, Output Y
Channel 4, Output Y
Positive Supply
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
3
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)
MIN
MAX
–0.5
UNIT
VCC
Supply voltage
IIK
Input clamp current(2)
VI < 0 or VI > VCC
±20
7
mA
V
IOK
Output clamp current(2)
VO < 0 or VO > VCC
±20
mA
IO
Continuous output current
VO = 0 to VCC
±35
mA
ICC
Continuous current through VCC or GND
±70
mA
TJ
Junction temperature
150
°C
Tstg
Storage temperature
150
°C
(1)
(2)
–65
Stresses beyond those listed under Absolute Maximum Rating may cause permanent damage to the device. These are stress
ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated
under Recommended Operating Condition. Exposure to absolute-maximum-rated conditions for extended periods may affect device
reliability.
The input and output voltage ratings may be exceeded if the input and output current ratings are observed.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
Electrostatic discharge
Human body model (HBM), per AEC Q100-002(1)
HBM ESD Classification Level 2
±4000
Charged device model (CDM), per AEC
Q100-011
CDM ESD Classification Level C4B
±1500
UNIT
V
AEC Q100-002 indicate that HBM stressing shall be in accordrance with the ANSI/ESDA/JEDEC JS-001 specification.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
5
MAX
UNIT
VCC
Supply voltage
2
6
V
VI
Input voltage
0
VCC
V
VO
Output voltage
0
VCC
V
TA
Ambient temperature
–40
125
°C
6.4 Thermal Information
SN74HCS126-Q1
THERMAL METRIC(1)
RθJA
Junction-to-ambient thermal resistance
PW (TSSOP)
UNIT
14 PINS
14 PINS
133.6
151.7
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
89
79.4
°C/W
RθJB
Junction-to-board thermal resistance
89.5
94.7
°C/W
ΨJT
Junction-to-top characterization parameter
45.5
25.2
°C/W
ΨJB
Junction-to-board characterization parameter
89.1
94.1
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
N/A
°C/W
(1)
4
D (SOIC)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
6.5 Electrical Characteristics
over operating free-air temperature range (unless otherwise noted)
PARAMETER
VT+
VT-
ΔVT
VOH
VOL
TEST CONDITIONS
VCC
Positive switching threshold
Negative switching threshold
Hysteresis (VT+ - VT-)
High-level output voltage
Low-level output voltage
VI = VIH or VIL
VI = VIH or VIL
TYP(1)
MIN
MAX UNIT
2V
0.7
1.5
4.5 V
1.7
3.15
6V
2.1
4.2
2V
0.3
1
4.5 V
0.9
2.2
6V
1.2
3
2V
0.2
1
4.5 V
0.4
1.4
6V
0.6
1.6
IOH = -20 µA
2 V to 6 V
IOH = -6 mA
4.5 V
IOH = -7.8 mA
6V
IOL = 20 µA
2 V to 6 V
VCC – 0.1
VCC – 0.002
4
4.3
5.4
V
V
V
V
5.75
0.002
0.1
IOL = 6 mA
4.5 V
0.18
0.3
IOL = 7.8 mA
6V
0.22
0.33
V
II
Input leakage current
VI = VCC or 0
6V
±100
±1000
nA
IOZ
Off-state (high-impedance
state) output current
VO = VCC or 0
6V
0.01
2
µA
ICC
Supply current
VI = VCC or 0, IO = 0
6V
0.1
2
µA
Ci
Input capacitance
5
pF
(1)
2 V to 6 V
TA = 25°C
6.6 Switching Characteristics
over operating free-air temperature range (unless otherwise noted)
PARAMETER
FROM (INPUT)
TO (OUTPUT)
TYP(1)
MAX
15
50
8
30
6V
7
26
2V
18
36
4.5 V
9
14
6V
7
12
2V
15
27
4.5 V
10
17
9
14
VCC
2V
tpd
ten
tdis
Propagation delay
Enable time
Disable time
A
OE
OE
Y
Y
Y
4.5 V
6V
tt
(1)
Transition-time
Any
MIN
2V
9
16
4.5 V
5
9
6V
4
8
UNIT
ns
ns
ns
ns
TA = 25°C
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
5
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
6.7 Operating Characteristics
over operating free-air temperature range (unless otherwise noted)
PARAMETER
Cpd
TEST CONDITIONS
Power dissipation capacitance per gate
(1)
MIN
No load
TYP(1)
MAX
UNIT
10
pF
TA = 25°C
6.8 Typical Characteristics
TA = 25°C
70
46
VCC = 2 V
VCC = 3.3 V
VCC = 4.5 V
VCC = 6 V
Output Resistance (:)
42
VCC = 2 V
VCC = 3.3 V
VCC = 4.5 V
VCC = 6 V
65
Output Resistance (:)
44
40
38
36
34
32
60
55
50
45
40
30
35
28
26
30
0
2.5
5
7.5 10 12.5 15 17.5
Output Sink Current (mA)
20
22.5
25
Figure 6-1. Output driver resistance in LOW state.
0
ICC ± Supply Current (mA)
VCC = 2.5 V
0.14
VCC = 3.3 V
ICC ± Supply Current (mA)
VCC = 2 V
0.16
0.12
0.1
0.08
0.06
0.04
0.02
0
0
0.5
1
1.5
2
2.5
VI ± Input Voltage (V)
3
3.5
Figure 6-3. Supply current across input voltage, 2-,
2.5-, and 3.3-V supply
6
5
7.5 10 12.5 15 17.5
Output Source Current (mA)
20
22.5
25
Figure 6-2. Output driver resistance in HIGH state.
0.2
0.18
2.5
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
VCC = 4.5 V
VCC = 5 V
VCC = 6 V
0
0.5
1
1.5
2 2.5 3 3.5 4
VI ± Input Voltage (V)
4.5
5
5.5
6
Figure 6-4. Supply current across input voltage,
4.5-, 5-, and 6-V supply
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
7 Parameter Measurement Information
Phase relationships between waveforms were chosen arbitrarily. All input pulses are supplied by generators
having the following characteristics: PRR ≤ 1 MHz, ZO = 50 Ω, tt < 2.5 ns.
For clock inputs, fmax is measured when the input duty cycle is 50%.
The outputs are measured one at a time with one input transition per measurement.
VCC
Test
Point
VCC
Input
50%
50%
S1
0V
RL
From Output
Under Test
CL(1)
tPHL(1)
tPLH(1)
VOH
S2
Output
50%
50%
VOL
(1) CL includes probe and test-fixture capacitance.
tPLH(1)
tPHL(1)
Figure 7-1. Load Circuit for 3-State Outputs
VOH
Output
50%
50%
VOL
(1) The greater between tPLH and tPHL is the same as tpd.
Figure 7-2. Voltage Waveforms Propagation Delays
VCC
Output
Control
50%
90%
Input
50%
Output
Waveform 1
S1 at VLOAD(1)
Output
Waveform 2
S1 at GND(2)
tr(1)
tPLZ(4)
§ 9CC
0V
tf(1)
90%
VOH
90%
Output
50%
10%
10%
VOL
tPZH(3)
10%
10%
0V
tPZL(3)
VCC
90%
tPHZ(4)
90%
VOH
50%
10%
tr(1)
tf(1)
VOL
(1) The greater between tr and tf is the same as tt.
Figure 7-4. Voltage Waveforms, Input and Output
Transition Times
§0V
Figure 7-3. Voltage Waveforms Propagation Delays
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
7
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
8 Detailed Description
8.1 Overview
This device contains four independent buffer with 3-state outputs and Schmitt-trigger inputs. Each gate performs
the Boolean function Y = A in positive logic.
8.2 Functional Block Diagram
One of Four Channels
xOE
xA
xY
8.3 Feature Description
8.3.1 Balanced CMOS 3-State Outputs
This device includes balanced CMOS 3-State outputs. The three states that these outputs can be in are driving
high, driving low, and high impedance. The term "balanced" indicates that the device can sink and source similar
currents. The drive capability of this device may create fast edges into light loads so routing and load conditions
should be considered to prevent ringing. Additionally, the outputs of this device are capable of driving larger
currents than the device can sustain without being damaged. It is important for the output power of the device
to be limited to avoid damage due to overcurrent. The electrical and thermal limits defined in the Absolute
Maximum Ratings must be followed at all times.
When placed into the high-impedance mode, the output will neither source nor sink current, with the exception of
minor leakage current as defined in the Electrical Characteristics table. In the high-impedance state, the output
voltage is not controlled by the device and is dependent on external factors. If no other drivers are connected
to the node, then this is known as a floating node and the voltage is unknown. A pull-up or pull-down resistor
can be connected to the output to provide a known voltage at the output while it is in the high-impedance state.
The value of the resistor will depend on multiple factors, including parasitic capacitance and power consumption
limitations. Typically, a 10 kΩ resistor can be used to meet these requirements.
Unused 3-state CMOS outputs should be left disconnected.
8.3.2 CMOS Schmitt-Trigger Inputs
This device includes inputs with the Schmitt-trigger architecture. These inputs are high impedance and are
typically modeled as a resistor in parallel with the input capacitance given in the Electrical Characteristics table
from the input to ground. The worst case resistance is calculated with the maximum input voltage, given in the
Absolute Maximum Ratings table, and the maximum input leakage current, given in the Electrical Characteristics
table, using Ohm's law (R = V ÷ I).
The Schmitt-trigger input architecture provides hysteresis as defined by ΔVT in the Electrical Characteristics
table, which makes this device extremely tolerant to slow or noisy inputs. While the inputs can be driven much
slower than standard CMOS inputs, it is still recommended to properly terminate unused inputs. Driving the
inputs with slow transitioning signals will increase dynamic current consumption of the device. For additional
information regarding Schmitt-trigger inputs, please see Understanding Schmitt Triggers.
8.3.3 Clamp Diode Structure
The inputs and outputs to this device have both positive and negative clamping diodes as depicted in Electrical
Placement of Clamping Diodes for Each Input and Output.
8
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
CAUTION
Voltages beyond the values specified in the Absolute Maximum Ratings table can cause damage
to the device. The input and output voltage ratings may be exceeded if the input and output clampcurrent ratings are observed.
VCC
Device
+IIK
+IOK
Logic
Input
Output
-IIK
-IOK
GND
Figure 8-1. Electrical Placement of Clamping Diodes for Each Input and Output
8.4 Device Functional Modes
Table 8-1. Function Table
INPUTS
OUTPUT
OE
A
Y
L
X
Z
H
L
L
H
H
H
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
9
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
9 Application and Implementation
Note
Information in the following applications sections is not part of the TI component specification,
and TI does not warrant its accuracy or completeness. TI’s customers are responsible for
determining suitability of components for their purposes, as well as validating and testing their design
implementation to confirm system functionality.
9.1 Application Information
In this application, a buffer with a 3-state output is used to disable a data signal as shown in Figure 9-1. The
remaining three buffers can be used for signal conditioning in other places in the system, or the inputs can be
grounded and the channels left unused.
9.2 Typical Application
System
Controller
OE
Data
A
Y
Output
Figure 9-1. Typical application block diagram
9.2.1 Design Requirements
9.2.1.1 Power Considerations
Ensure the desired supply voltage is within the range specified in the Recommended Operating Conditions. The
supply voltage sets the device's electrical characteristics as described in the Electrical Characteristics.
The positive voltage supply must be capable of sourcing current equal to the total current to be sourced by all
outputs of the SN74HCS126-Q1 plus the maximum static supply current, ICC, listed in Electrical Characteristics
and any transient current required for switching. The logic device can only source as much current as is provided
by the positive supply source. Be sure not to exceed the maximum total current through VCC listed in the
Absolute Maximum Ratings.
The ground must be capable of sinking current equal to the total current to be sunk by all outputs of the
SN74HCS126-Q1 plus the maximum supply current, ICC, listed in Electrical Characteristics, and any transient
current required for switching. The logic device can only sink as much current as can be sunk into its ground
connection. Be sure not to exceed the maximum total current through GND listed in the Absolute Maximum
Ratings.
The SN74HCS126-Q1 can drive a load with a total capacitance less than or equal to 50 pF while still meeting
all of the datasheet specifications. Larger capacitive loads can be applied, however it is not recommended to
exceed 50 pF.
The SN74HCS126-Q1 can drive a load with total resistance described by RL ≥ VO / IO, with the output voltage
and current defined in the Electrical Characteristics table with VOH and VOL. When outputting in the high state,
the output voltage in the equation is defined as the difference between the measured output voltage and the
supply voltage at the VCC pin.
Total power consumption can be calculated using the information provided in CMOS Power Consumption and
Cpd Calculation.
Thermal increase can be calculated using the information provided in Thermal Characteristics of Standard Linear
and Logic (SLL) Packages and Devices.
10
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
CAUTION
The maximum junction temperature, TJ(max) listed in the Absolute Maximum Ratings, is an additional
limitation to prevent damage to the device. Do not violate any values listed in the Absolute Maximum
Ratings. These limits are provided to prevent damage to the device.
9.2.1.2 Input Considerations
Input signals must cross Vt-(min) to be considered a logic LOW, and Vt+(max) to be considered a logic HIGH. Do
not exceed the maximum input voltage range found in the Absolute Maximum Ratings.
Unused inputs must be terminated to either VCC or ground. These can be directly terminated if the input is
completely unused, or they can be connected with a pull-up or pull-down resistor if the input is to be used
sometimes, but not always. A pull-up resistor is used for a default state of HIGH, and a pull-down resistor is used
for a default state of LOW. The resistor size is limited by drive current of the controller, leakage current into the
SN74HCS126-Q1, as specified in the Electrical Characteristics, and the desired input transition rate. A 10-kΩ
resistor value is often used due to these factors.
The SN74HCS126-Q1 has no input signal transition rate requirements because it has Schmitt-trigger inputs.
Another benefit to having Schmitt-trigger inputs is the ability to reject noise. Noise with a large enough amplitude
can still cause issues. To know how much noise is too much, please refer to the ΔVT(min) in the Electrical
Characteristics. This hysteresis value will provide the peak-to-peak limit.
Unlike what happens with standard CMOS inputs, Schmitt-trigger inputs can be held at any valid value without
causing huge increases in power consumption. The typical additional current caused by holding an input at a
value other than VCC or ground is plotted in the Typical Characteristics.
Refer to the Feature Description section for additional information regarding the inputs for this device.
9.2.1.3 Output Considerations
The positive supply voltage is used to produce the output HIGH voltage. Drawing current from the output will
decrease the output voltage as specified by the VOH specification in the Electrical Characteristics. The ground
voltage is used to produce the output LOW voltage. Sinking current into the output will increase the output
voltage as specified by the VOL specification in the Electrical Characteristics.
Push-pull outputs that could be in opposite states, even for a very short time period, should never be connected
directly together. This can cause excessive current and damage to the device.
Two channels within the same device with the same input signals can be connected in parallel for additional
output drive strength.
Unused outputs can be left floating. Do not connect outputs directly to VCC or ground.
Refer to Feature Description section for additional information regarding the outputs for this device.
9.2.2 Detailed Design Procedure
1. Add a decoupling capacitor from VCC to GND. The capacitor needs to be placed physically close to the
device and electrically close to both the VCC and GND pins. An example layout is shown in the Layout
section.
2. Ensure the capacitive load at the output is ≤ 50 pF. This is not a hard limit, however it will ensure
optimal performance. This can be accomplished by providing short, appropriately sized traces from the
SN74HCS126-Q1 to the receiving device(s).
3. Ensure the resistive load at the output is larger than (VCC / IO(max)) Ω. This will ensure that the maximum
output current from the Absolute Maximum Ratings is not violated. Most CMOS inputs have a resistive load
measured in megaohms; much larger than the minimum calculated above.
4. Thermal issues are rarely a concern for logic gates, however the power consumption and thermal increase
can be calculated using the steps provided in the application report, CMOS Power Consumption and Cpd
Calculation.
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
11
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
9.2.3 Application Curves
Data
Output
OE
Figure 9-2. Application timing diagram
12
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
10 Power Supply Recommendations
The power supply can be any voltage between the minimum and maximum supply voltage rating located in the
Recommended Operating Conditions. Each VCC terminal should have a good bypass capacitor to prevent power
disturbance. A 0.1-μF capacitor is recommended for this device. It is acceptable to parallel multiple bypass caps
to reject different frequencies of noise. The 0.1-μF and 1-μF capacitors are commonly used in parallel. The
bypass capacitor should be installed as close to the power terminal as possible for best results, as shown in
given example layout image.
11 Layout
11.1 Layout Guidelines
When using multiple-input and multiple-channel logic devices inputs must not ever be left floating. In many
cases, functions or parts of functions of digital logic devices are unused; for example, when only two inputs of a
triple-input AND gate are used or only 3 of the 4 buffer gates are used. Such unused input pins must not be left
unconnected because the undefined voltages at the outside connections result in undefined operational states.
All unused inputs of digital logic devices must be connected to a logic high or logic low voltage, as defined by the
input voltage specifications, to prevent them from floating. The logic level that must be applied to any particular
unused input depends on the function of the device. Generally, the inputs are tied to GND or VCC, whichever
makes more sense for the logic function or is more convenient.
11.2 Layout Example
GND
VCC
Recommend GND flood fill for
improved signal isolation, noise
reduction, and thermal dissipation
0.1 F
Avoid 90°
corners for
signal lines
Bypass capacitor
placed close to
the device
Unused inputs
tied to VCC
1OE
1
14
VCC
1A
2
13
4OE
1Y
3
12
4A
2OE
4
11
4Y
2A
5
10
3OE
2Y
6
9
3A
GND
7
8
3Y
Unused output
left floating
Figure 11-1. Example layout for the SN74HCS126-Q1
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
13
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
12 Device and Documentation Support
TI offers an extensive line of development tools. Tools and software to evaluate the performance of the device,
generate code, and develop solutions are listed below.
12.1 Documentation Support
12.1.1 Related Documentation
For related documentation see the following:
•
•
•
Texas Instruments, HCMOS Design Considerations application report (SCLA007)
Texas Instruments, CMOS Power Consumption and Cpd Calculation application report (SDYA009)
Texas Instruments, Designing With Logic application report
12.2 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. Click on
Subscribe to updates to register and receive a weekly digest of any product information that has changed. For
change details, review the revision history included in any revised document.
12.3 Support Resources
TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight
from the experts. Search existing answers or ask your own question to get the quick design help you need.
Linked content is provided "AS IS" by the respective contributors. They do not constitute TI specifications and do
not necessarily reflect TI's views; see TI's Terms of Use.
12.4 Trademarks
TI E2E™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
12.5 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled
with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric changes could cause the device not to meet its published
specifications.
12.6 Glossary
TI Glossary
14
This glossary lists and explains terms, acronyms, and definitions.
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
SN74HCS126-Q1
www.ti.com
SCLS753A – JUNE 2020 – REVISED MARCH 2021
13 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated
Product Folder Links: SN74HCS126-Q1
15
PACKAGE OPTION ADDENDUM
www.ti.com
5-Mar-2021
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)
SN74HCS126QDRQ1
ACTIVE
SOIC
D
14
2500
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
HCS126Q1
SN74HCS126QPWRQ1
ACTIVE
TSSOP
PW
14
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
HCS126Q
(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