SN74HCS74
SCLS782D – NOVEMBER 2019 – REVISED DECEMBER 2021
SN74HCS74 Schmitt-Trigger Input Dual D-Type Positive-Edge-Triggered Flip-Flops
With Clear and Preset
1 Features
3 Description
•
•
The device contains two independent D-type positiveedge-triggered flip-flops. All inputs include Schmitt
triggers, allowing for slow or noisy input signals. A low
level at the preset ( PRE) input sets the output high. A
low level at the clear ( CLR) input resets the output
low. Preset and clear functions are asynchronous
and not dependent on the levels of the other inputs.
When PRE and CLR are inactive (high), data at the
data (D) input meeting the setup time requirements is
transferred to the outputs (Q, Q) on the positive-going
edge of the clock (CLK) pulse. Clock triggering occurs
at a voltage level and is not directly related to the
rise time of the input clock (CLK) signal. Following the
hold-time interval, data at the data (D) input can be
changed without affecting the levels at the outputs (Q,
Q).
2 Applications
Convert a momentary switch to a toggle switch
Hold a signal during controller reset
Input slow edge-rate signals
Operate in noisy environments
Divide a clock signal by two
Device Information
PART NUMBER
PACKAGE(1)
BODY SIZE (NOM)
SN74HCS74PW
TSSOP (14)
5.00 mm × 4.40 mm
SN74HCS74D
SOIC (14)
8.70 mm × 3.90 mm
SN74HCS74BQA
WQFN (14)
3.00 mm × 2.50 mm
SN74HCS74DYY
SOT-23-THIN (14)
2.00 mm x 4.20 mm
(1)
Voltage
Output
Current
Voltage
Current
Output
Input Voltage
Time
Output
Time
Voltage
Time
Input Voltage
Current
Response
Waveforms
Time
Time
Output
Schmitt-trigger
CMOS Input
Supply Current
Response
Waveforms
Supports Slow Inputs
Input
Voltage
Noise Rejection
Input Voltage
Standard
CMOS Input
For all available packages, see the orderable addendum at
the end of the data sheet.
Input
Voltage
Input Voltage
Waveforms
Input
Voltage
Low Power
Supply Current
•
•
•
•
•
Voltage
•
•
Current
•
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
Extended ambient temperature range: –40°C to
+125°C, TA
Time
Benefits of Schmitt-trigger inputs
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
SN74HCS74
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SCLS782D – NOVEMBER 2019 – REVISED DECEMBER 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 Timing Characteristics.................................................6
6.8 Typical Characteristics................................................ 7
7 Parameter Measurement Information............................ 8
8 Detailed Description........................................................9
8.1 Overview..................................................................... 9
8.2 Functional Block Diagram........................................... 9
8.3 Feature Description.....................................................9
8.4 Device Functional Modes..........................................10
9 Application and Implementation.................................. 11
9.1 Application Information..............................................11
9.2 Typical Application.................................................... 11
10 Power Supply Recommendations..............................14
11 Layout........................................................................... 14
11.1 Layout Guidelines................................................... 14
11.2 Layout Example...................................................... 14
12 Device and Documentation Support..........................15
12.1 Documentation Support.......................................... 15
12.2 Receiving Notification of Documentation Updates..15
12.3 Support Resources................................................. 15
12.4 Trademarks............................................................. 15
12.5 Electrostatic Discharge Caution..............................15
12.6 Glossary..................................................................15
13 Mechanical, Packaging, and Orderable
Information.................................................................... 16
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision C (January 2021) to Revision D (December 2021)
Page
• Added DYY package information to Device Information.....................................................................................1
• Added DYY package information to Pin Configuration and Functions .............................................................. 3
• Added DYY package to Thermal Information table........................................................................................... 4
Changes from Revision B (November 2020) to Revision C (January 2021)
Page
• Changed BQA package status from Preview to Active.......................................................................................1
• Changed data sheet status from Mixed Status to Production Data.................................................................... 1
Changes from Revision A (May 2020) to Revision B (November 2020)
Page
• Updated the numbering format for tables, figures, and cross-references throughout the document..................1
• Added BQA package information to Device Information.................................................................................... 1
• Added BQA pinout diagram and package information to Pin Configuration and Functions .............................. 3
• Added BQA package to Thermal Information table............................................................................................ 4
Changes from Revision * (November 2019) to Revision A (May 2020)
Page
• Added D package information to Device Information......................................................................................... 1
• Added D package information to Pin Configuration and Functions ................................................................... 3
• Added D package column to Thermal Information table.....................................................................................4
2
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5 Pin Configuration and Functions
1CLR VCC
1CLR
1D
1
14
VCC
2
13
2CLR
1D
2
1CLK
1PRE
3
12
4
11
2D
2CLK
1CLK
3
1Q
5
10
2PRE
1PRE
4
1Q
6
9
2Q
1Q
5
GND
7
8
2Q
1Q
6
1
D, PW or DYY Package
14-Pin SOIC, TSSOP or SOT
Top View
14
PAD
7
8
GND
2Q
13
2CLR
12
2D
11
2CLK
10
2PRE
9
2Q
BQA Package
14-Pin WQFN
Top View
Pin Functions
PIN
DESCRIPTION
NO.
1 CLR
1
Input
Clear for channel 1, active low
1D
2
Input
Data for channel 1
1CLK
3
Input
Clock for channel 1, rising edge triggered
1 PRE
4
Input
Preset for channel 1, active low
1Q
5
Output
Output for channel 1
Inverted output for channel 1
1Q
6
Output
GND
7
—
2Q
8
Output
Inverted output for channel 2
2Q
9
Output
Output for channel 2
2 PRE
10
Input
Preset for channel 2, active low
2CLK
11
Input
Clock for channel 2, rising edge triggered
2D
12
Input
Data for channel 2
2 CLR
13
Input
Clear for channel 2, active low
VCC
14
—
Positive supply
—
The thermal pad can be connected to GND or left floating. Do not connect to any other
signal or supply
Thermal Pad
(1)
TYPE
NAME
(1)
Ground
BQA package only.
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)
VCC
Supply voltage
MIN
MAX
–0.5
7
UNIT
V
IIK
Input clamp current(2)
VI < –0.5 V or VI > VCC +
0.5 V
IOK
Output clamp current(2)
VI < –0.5 V or VI > VCC +
0.5 V
±20
mA
IO
Continuous output current
VO = 0 to VCC
±35
mA
±20
mA
Continuous current through VCC or GND
±70
mA
TJ
Junction temperature(3)
150
°C
Tstg
Storage temperature
150
°C
(1)
(2)
(3)
–65
Operation outside the Absolute Maximum Ratings may cause permanent device damage. Absolute maximum ratings do not imply
functional operation of the device at these or any other conditions beyond those listed under Recommended Operating Conditions.
If briefly operating outside the Recommended Operating Conditions but within the Absolute Maximum Ratings, the device may not
sustain damage, but it may not be fully functional. Operating the device in this manner may affect device reliability, functionality,
performance, and shorten the device lifetime.
The input and output voltage ratings may be exceeded if the input and output current ratings are observed.
Assured by design.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/
JEDEC JS-001(1)
±4000
Charged-device model (CDM), per ANSI/ESDA/
JEDEC JS-002(2)
±1500
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
MAX
VCC
Supply voltage
2
5
6
UNIT
V
VI
Input voltage
0
VCC
V
VO
Output voltage
0
VCC
V
TA
Ambient temperature
–40
125
°C
6.4 Thermal Information
SN74HCS74
THERMAL
4
METRIC(1)
PW (TSSOP)
D (SOIC)
BQA (WQFN)
DYY (SOT)
14 PINS
14 PINS
14 PINS
14 PINS
UNIT
RθJA
Junction-to-ambient thermal
resistance
151.7
133.6
109.7
236.5
°C/W
RθJC(top)
Junction-to-case (top) thermal
resistance
79.4
89.0
111.0
143.2
°C/W
RθJB
Junction-to-board thermal
resistance
94.7
89.5
77.9
146.0
°C/W
ΨJT
Junction-to-top characterization
parameter
25.2
45.5
20.2
29.5
°C/W
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SN74HCS74
THERMAL METRIC(1)
PW (TSSOP)
D (SOIC)
BQA (WQFN)
DYY (SOT)
UNIT
14 PINS
14 PINS
14 PINS
14 PINS
ΨJB
Junction-to-board characterization
parameter
94.1
89.1
77.8
145.6
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal
resistance
N/A
N/A
56.6
N/A
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
6.5 Electrical Characteristics
over operating free-air temperature range; typical values measured at TA = 25°C (unless otherwise noted).
PARAMETER
VT+
VT-
ΔVT
TEST CONDITIONS
VCC
Positive switching threshold
Negative switching threshold
Hysteresis (VT+ - VT-)(1)
MIN
High-level output voltage
VI = VIH or VIL
MAX UNIT
2V
0.7
1.5
4.5 V
1.7
3.15
6V
2.1
4.2
2V
0.3
1.0
4.5 V
0.9
2.2
6V
1.2
3.0
2V
0.2
1.0
4.5 V
0.4
1.4
6V
VOH
TYP
0.6
VCC – 0.1
V
V
V
1.6
IOH = -20 µA
2 V to 6 V
VCC – 0.002
IOH = -6 mA
4.5 V
4.0
4.3
IOH = -7.8 mA
6V
5.4
5.75
IOL = 20 µA
2 V to 6 V
IOL = 6 mA
4.5 V
IOL = 7.8 mA
V
0.002
0.1
0.18
0.30
VOL
Low-level output voltage
VI = VIH or VIL
6V
0.22
0.33
II
Input leakage current
VI = VCC or 0
6V
±100
±1000
nA
ICC
Supply current
VI = VCC or 0, IO = 0
6V
0.1
2
µA
Ci
Input capacitance
2 V to 6 V
5
pF
Cpd
Power dissipation capacitance
No load
per gate
2 V to 6 V
(1)
10
V
pF
Guaranteed by design.
6.6 Switching Characteristics
CL = 50 pF; over operating free-air temperature range; typical values measured at TA = 25°C (unless otherwise
noted). See Parameter Measurement Information
PARAMETER
fmax
FROM (INPUT)
TO (OUTPUT)
Max switching frequency
MIN
TYP
2V
VCC
18
31
4.5 V
45
95
6V
65
105
2V
PRE or CLR
tpd
Q or Q
Propagation delay
CLK
Q or Q
MAX
MHz
19
42
8
19
6V
7
15
2V
19
42
4.5 V
8
19
6V
7
15
4.5 V
UNIT
ns
ns
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CL = 50 pF; over operating free-air temperature range; typical values measured at TA = 25°C (unless otherwise
noted). See Parameter Measurement Information
PARAMETER
tt
FROM (INPUT)
Transition-time
TO (OUTPUT)
Q or Q
VCC
MIN
TYP
MAX
2V
9
16
4.5 V
5
9
6V
4
8
UNIT
ns
6.7 Timing Characteristics
CL = 50 pF; over operating free-air temperature range (unless otherwise noted). See Parameter Measurement Information.
PARAMETER
fclock
VCC
Clock frequency
PRE or CLR low
tw
Pulse duration
CLK high or low
Data
tsu
Setup time before CLK high
PRE or CLR inactive
th
6
Hold time
Data after CLK↑
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MIN
MAX
2V
18
4.5 V
45
6V
65
2V
11
4.5 V
11
6V
11
2V
14
4.5 V
12
6V
11
2V
24
4.5 V
9
6V
6
2V
7
4.5 V
5
6V
5
2V
0
4.5 V
0
6V
0
UNIT
MHz
ns
ns
ns
ns
ns
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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
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
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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.
tw
Test
Point
VCC
Input
From Output
Under Test
50%
50%
0V
Figure 7-2. Voltage Waveforms, Pulse Duration
CL(1)
(1) CL includes probe and test-fixture capacitance.
Figure 7-1. Load Circuit for Push-Pull Outputs
VCC
VCC
Clock
Input
Input
50%
50%
50%
0V
0V
tsu
tPLH
th
(1)
tPHL
(1)
VOH
VCC
Data
Input
50%
Output
50%
50%
50%
VOL
0V
Figure 7-3. Voltage Waveforms, Setup and Hold
Times
tPLH(1)
tPHL(1)
VOH
Output
50%
50%
VOL
(1) The greater between tPLH and tPHL is the same as tpd.
Figure 7-4. Voltage Waveforms Propagation Delays
90%
VCC
90%
Input
10%
10%
tr(1)
0V
tf(1)
90%
VOH
90%
Output
10%
10%
tr(1)
tf(1)
VOL
(1) The greater between tr and tf is the same as tt.
Figure 7-5. Voltage Waveforms, Input and Output Transition Times
8
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8 Detailed Description
8.1 Overview
Logic Diagram (Positive Logic) for one channel of SN74HCS74 describes the SN74HCS74. As the SN74HCS74
is a dual D-Type positive-edge-triggered flip-flop with clear and preset, the diagram below describes one of the
two device flip-flops.
8.2 Functional Block Diagram
Figure 8-1. Logic Diagram (Positive Logic) for one channel of SN74HCS74
8.3 Feature Description
8.3.1 Balanced CMOS Push-Pull Outputs
This device includes balanced CMOS push-pull outputs. 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.
Unused push-pull 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).
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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.
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 8-2. Electrical Placement of Clamping Diodes for Each Input and Output
8.4 Device Functional Modes
Function Table lists the functional modes of the SN74HCS74.
Table 8-1. Function Table
INPUTS
(1)
10
OUTPUTS
PRE
CLR
CLK
D
Q
Q
L
H
X
X
H
L
H
L
X
X
L
H
L
L
X
X
H(1)
H(1)
H
H
↑
H
H
L
H
H
↑
L
L
H
H
H
L
X
Q0
Q0
This configuration is nonstable; that is, it does not persist when PRE or CLR returns to its inactive
(high) level.
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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
Toggle switches are typically large, mechanically complex and relatively expensive. It is desirable to use a
momentary switch instead because they are small, mechanically simple and low cost. Some systems require a
toggle switch's functionality but are space or cost constrained and must use a momentary switch instead. The
SN74HCS74 has integrated Schmitt-trigger inputs that eliminate the need for a second IC for signal conditioning,
reducing the required board space. This makes the SN74HCS74 an ideal device for converting a momentary
switch into a toggle switch.
If the data input (D) of the SN74HCS74 is tied to the inverted output ( Q), then each clock pulse will cause the
value at the output (Q) to toggle. The momentary switch can be debounced and directly connected to the clock
input (CLK) to toggle the output.
9.2 Typical Application
VCC
R1
R2
VCC
C1
VCC
R3
C3
C2
VCC
PRE
CLK
D
Q
CLR
Q
GND
Output
Figure 9-1. Device Power Button Circuit
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 SN74HCS74 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
SN74HCS74 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.
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The SN74HCS74 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 SN74HCS74 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.
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
SN74HCS74, 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 SN74HCS74 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.
12
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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 SN74HCS74
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.
9.2.3 Application Curve
Voltage (2 V/div)
Voltage (2 V/div)
Circuit response without RC debounce
Vin := CLK input, Vout := Q output illustrates an example of a single button press bouncing and causing the
output to toggle multiple times. This will cause issues in the desired application. Circuit response with RC
debounce
Vin := CLK input, Vout := Q output illustrates 4 button presses with an added debounce circuit, fixing the
unwanted toggling and allowing for proper toggle switch operation.
Vout
Vin
Vout
Vin
Time (200 ms/div)
Time (100 Ps/div)
D001
Figure 9-2. Circuit response without RC debounce
Vin := CLK input, Vout := Q output
D002
Figure 9-3. Circuit response with RC debounce
Vin := CLK input, Vout := Q output
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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
1CLR
1
14
VCC
1D
2
13
2CLR
1CLK
3
12
2D
1PRE
4
11
2CLK
1Q
5
10
2PRE
1Q
6
9
2Q
GND
7
8
2Q
Unused output
left floating
Figure 11-1. Layout Example of the SN74HCS74
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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
This glossary lists and explains terms, acronyms, and definitions.
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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.
16
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PACKAGE OPTION ADDENDUM
www.ti.com
7-Dec-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)
SN74HCS74BQAR
ACTIVE
WQFN
BQA
14
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
HCS74
SN74HCS74DR
ACTIVE
SOIC
D
14
2500
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
HCS74
SN74HCS74PWR
ACTIVE
TSSOP
PW
14
2000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
HCS74
(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