CD74HCT21
SCHS418 – MARCH 2020
CD74HCT21 Dual 4-Input AND Gates
1 Features
3 Description
•
This device contains two independent 4-input AND
gates. Each gate performs the Boolean function
Y = A ● B ● C ● D in positive logic.
•
•
•
•
•
•
LSTTL input logic compatible
– VIL(max) = 0.8 V, VIH(min) = 2 V
CMOS input logic compatible
– II ≤ 1 µA at VOL, VOH
Buffered inputs
4.5 V to 5.5 V operation
Wide operating temperature range:
-55°C to +125°C
Supports fanout up to 10 LSTTL loads
Significant power reduction compared to LSTTL
logic ICs
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
CD74HCT21M
SOIC (14)
8.70 mm × 3.90 mm
CD74HCT21E
PDIP (14)
19.30 mm × 6.40 mm
(1)
For all available packages, see the orderable addendum at
the end of the data sheet.
2 Applications
•
•
Combining power good signals
Enable digital signals
1A
1B
NC
1C
1D
1Y
GND
1
14
2
13
3
12
4
11
VCC
2D
2C
NC
5
10
6
9
7
8
2B
2A
2Y
Functional pinout
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.
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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........................................... 5
6.8 Typical Characteristics................................................ 5
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..............................12
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 Support Resources................................................. 14
12.3 Trademarks............................................................. 14
12.4 Electrostatic Discharge Caution..............................14
12.5 Glossary..................................................................14
13 Mechanical, Packaging, and Orderable
Information.................................................................... 14
4 Revision History
2
DATE
REVISION
NOTES
March 2020
*
Initial release. Moved the HCT devices from
the SCHS131 to a standalone data sheet.
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5 Pin Configuration and Functions
1A
1
14
VCC
1B
2
13
2D
NC
3
12
2C
1C
4
11
NC
1D
5
10
2B
1Y
6
9
2A
GND
7
8
2Y
Figure 5-1. D or N Package 14-Pin SOIC or PDIP Top View
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
1A
1
Input
Channel 1, Input A
1B
2
Input
Channel 1, Input B
NC
3, 11
—
1C
4
Input
Channel 1, Input C
1D
5
Input
Channel 1, Input D
1Y
6
Output
GND
7
—
2Y
8
Output
2A
9
Input
Channel 2, Input A
2B
10
Input
Channel 2, Input B
2C
12
Input
Channel 2, Input C
2D
13
Input
Channel 2, Input D
VCC
14
—
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Not internally connected
Channel 1, Output Y
Ground
Channel 2, Output Y
Positive Supply
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)
MIN
MAX
–0.5
7
UNIT
VCC
Supply voltage
IIK
Input clamp current(2)
VI < –0.5 V or VI > VCC +
0.5 V
±20
mA
IOK
Output clamp current(2)
VO < –0.5 V or VO > VCC +
0.5 V
±20
mA
IO
Continuous output current
VO > –0.5 V or VO < VCC +
0.5 V
±25
mA
±50
mA
150
°C
300
°C
150
°C
Continuous current through VCC or GND
TJ
Junction
temperature(3)
Lead temperature (soldering 10s)
Tstg
(1)
(2)
(3)
SOIC - Lead Tips Only
Storage temperature
–65
V
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.
Guaranteed by design.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/
JEDEC JS-001(1)
±2000
Charged-device model (CDM), per JEDEC
specification JESD22-C101(2)
±1000
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
VCC
Supply voltage
VIH
High-level input voltage
VCC = 4.5 V to 5.5 V
VIL
Low-level input voltage
VCC = 4.5 V to 5.5 V
VI
Input voltage
VO
Output voltage
tt
Input transition rise and fall time
TA
Operating free-air temperature
4.5
NOM
MAX
5.5
2
UNIT
V
V
0.8
V
0
VCC
V
0
VCC
V
VCC = 4.5 V
500
VCC = 5.5 V
400
–55
125
ns
°C
6.4 Thermal Information
CD74HCT21
THERMAL METRIC(1)
4
N (PDIP)
D (SOIC)
UNIT
14 PINS
14 PINS
RθJA
Junction-to-ambient thermal resistance
64.9
102.3
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
52.7
58.7
°C/W
RθJB
Junction-to-board thermal resistance
44.7
58.2
°C/W
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CD74HCT21
THERMAL METRIC(1)
N (PDIP)
D (SOIC)
UNIT
14 PINS
14 PINS
ΨJT
Junction-to-top characterization parameter
32.3
19.9
°C/W
ΨJB
Junction-to-board characterization parameter
44.4
57.8
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
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).
Operating free-air temperature (TA)
PARAMETER
TEST CONDITIONS
VCC
25°C
MIN
VOH
VOL
High-level
output voltage
VI = VIH
Low-level output
VI = VIL
voltage
TYP
–40°C to 85°C
MAX
MIN
TYP
–55°C to 125°C
MAX
MIN
TYP
UNIT
MAX
IOH = –20
µA
4.5 V
4.4
4.4
4.4
IOH = –4
mA
4.5 V
3.98
3.84
3.7
IOL = 20
µA
4.5 V
0.1
0.1
0.1
IOL = 4 mA 4.5 V
0.26
0.33
0.4
V
V
II
Input leakage
current
VI = VCC
and GND
IO = 0
5.5 V
±0.1
±1
±1
µA
ICC
Supply current
VI = VCC or
IO = 0
GND
5.5 V
2
20
40
µA
(1)
Additional
Quiescent
Device Current
Per Input Pin
VI = VCC –
2.1
4.5 V
to 5.5
V
360
450
490
µA
Ci
Input
capacitance
10
10
10
pF
ΔICC
(1)
100
5V
For dual-supply systems theoretical worst case (VI = 2.4 V, VCC = 5.5 V) specification is 1.8 mA.
6.6 Switching Characteristics
over operating free-air temperature range; typical values measured at TA = 25°C (unless otherwise noted).
PARAMETER
tpd
Propagation delay
tt
Transition-time
FROM
TO
Operating free-air temperature (TA)
TEST
CONDITIO
NS
VCC
A, B, C Y
or D
Y
CL = 50 pF
4.5 V
CL = 15 pF
5V
Y
CL = 50 pF
4.5 V
25°C
–40°C to 85°C
–55°C to 125°C
MIN TYP MAX
MIN TYP MAX
MIN TYP MAX
27
34
41
15
19
22
UNIT
ns
11
ns
6.7 Operating Characteristics
over operating free-air temperature range; typical values measured at TA = 25°C (unless otherwise noted).
PARAMETER
Cpd
TEST CONDITIONS
Power dissipation capacitance
No load
per gate
VCC
5V
MIN
TYP
42
MAX UNIT
pF
6.8 Typical Characteristics
TA = 25°C
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7
0.3
6
0.25
VOL Output Low Voltage (V)
VOH Output High Voltage (V)
SCHS418 – MARCH 2020
5
4
3
2
2-V
4.5-V
6-V
1
0
0.2
0.15
0.1
0.05
0
0
1
2
3
4
IOH Output High Current (mA)
5
6
Figure 6-1. Typical output voltage in the high state
(VOH)
6
2-V
4.5-V
6-V
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0
1
2
3
4
IOL Output Low Current (mA)
5
6
Figure 6-2. Typical output voltage in the low state
(VOL)
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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 < 6 ns.
The outputs are measured one at a time, with one input transition per measurement.
Test
Point
90%
VCC
90%
Input
10%
10%
tr(1)
From Output
Under Test
CL(1)
0V
tf(1)
90%
VOH
90%
Output
10%
A.
10%
tr(1)
CL= 50 pF and includes probe and jig capacitance.
A.
Figure 7-1. Load Circuit
tf(1)
VOL
tt is the greater of tr and tf.
Figure 7-2. Voltage Waveforms Transition Times
VCC
Input
50%
50%
0V
tPHL(1)
tPLH(1)
VOH
Output
50%
50%
VOL
tPLH(1)
tPHL(1)
VOH
Output
50%
50%
VOL
A.
The maximum between tPLH and tPHL is used for tpd.
Figure 7-3. Voltage Waveforms Propagation Delays
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8 Detailed Description
8.1 Overview
This device contains two independent 4-input AND gates. Each gate performs the Boolean function Y = A ● B
● C ● D in positive logic.
8.2 Functional Block Diagram
xA
xB
xY
xC
xD
8.3 Feature Description
8.3.1 Balanced CMOS Push-Pull Outputs
A balanced output allows the device to 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
over-current. The electrical and thermal limits defined in the Section 6.1 must be followed at all times.
The CD74HCT21 can drive a load with a total capacitance less than or equal to the maximum load listed in the
Section 6.6 connected to a high-impedance CMOS input while still meeting all of the datasheet specifications.
Larger capacitive loads can be applied, however it is not recommended to exceed the provided load value. If
larger capacitive loads are required, it is recommended to add a series resistor between the output and the
capacitor to limit output current to the values given in the Section 6.1.
8.3.2 TTL-Compatible CMOS Inputs
TTL-Compatible CMOS inputs are high impedance and are typically modeled as a resistor from the input to
ground in parallel with the input capacitance given in the Section 6.5. The worst case resistance is calculated
with the maximum input voltage, given in the Section 6.1, and the maximum input leakage current, given in the
Section 6.5, using ohm's law (R = V ÷ I).
Signals applied to the inputs need to have fast edge rates, as defined by Δt/Δv in the Section 6.3 to avoid
excessive current consumption and oscillations. If a slow or noisy input signal is required, a device with a
Schmitt-trigger input should be used to condition the input signal prior to the TTL-compatible CMOS input.
TTL-Compatible CMOS inputs have a lower threshold voltage than standard CMOS inputs to allow for
compatibility with older bipolar logic devices. See the Section 6.3 for the valid input voltages for the
CD74HCT21.
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8.3.3 Clamp Diode Structure
The inputs and outputs to this device have both positive and negative clamping diodes as depicted in Figure 8-1.
CAUTION
Voltages beyond the values specified in the Section 6.1 table can cause damage to the device.
The recommended input and output voltage ratings may be exceeded if the input and output clampcurrent ratings are observed.
Device
VCC
+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
A
B
C
D
Y
H
H
H
H
H
L
X
X
X
L
X
L
X
X
L
X
X
L
X
L
X
X
X
L
L
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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
In this application, this device is used to directly control the RESET pin of a motor controller. The controller
requires four input signals to all be HIGH before being enabled, and should be disabled in the event that any
one signal goes LOW. The 4-input AND gate function combines the four individual reset signals into a single
active-low reset signal.
9.2 Typical Application
Power Sup ply
Over Current
Detection
Motor Con trol ler
OC
PG
ON/OFF
RESET
CASE
On/Off Switch
Case Tamper
Switch
Figure 9-1. Typical application schematic
9.2.1 Design Requirements
9.2.1.1 Power Considerations
Ensure the desired supply voltage is within the range specified in the Section 6.3. The supply voltage sets the
device's electrical characteristics as described in the Section 6.5.
The supply must be capable of sourcing current equal to the total current to be sourced by all outputs of the
CD74HCT21 plus the maximum supply current, ICC, listed in the Section 6.5. The logic device can only source
or sink as much current as it is provided at the supply and ground pins, respectively. Be sure not to exceed the
maximum total current through GND or VCC listed in the Section 6.1.
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 Section 6.1, is an additional limitation to
prevent damage to the device. Do not violate any values listed in the Section 6.1. These limits are
provided to prevent damage to the device.
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9.2.1.2 Input Considerations
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
CD74HCT21, as specified in the Section 6.5, and the desired input transition rate. A 10-kΩ resistor value is often
used due to these factors.
Refer to the Section 8.3 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 Section 6.5. Similarly, 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 Section 6.5.
Unused outputs can be left floating. Do not connect outputs directly to VCC or ground.
Refer to Section 8.3 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 Figure 11-1.
2. Ensure the capacitive load at the output is ≤ 70 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 CD74HCT21
to the receiving device.
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 Section 6.1 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 Curves
OC
PG
ON/OFF
OT
RESET
Figure 9-2. Typical application timing diagram
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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 Section 6.3. Each VCC terminal should have a 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 Figure 11-1.
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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. 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
1A
1
14
VCC
1B
2
13
NC
3
12
2D Unused inputs
tied to VCC
2C
1C
4
11
NC
1D
5
10
2B
1Y
6
9
2A
GND
7
8
2Y
Figure 11-1. Example layout for the CD74HCT21
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12 Device and Documentation Support
12.1 Documentation Support
12.1.1 Related Documentation
For related documentation see the following:
• HCMOS Design Considerations
• CMOS Power Consumption and CPD Calculation
• Designing with Logic
12.2 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.
12.3 Trademarks
TI E2E™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
12.4 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.
12.5 Glossary
TI Glossary
This glossary lists and explains terms, acronyms, and definitions.
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.
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PACKAGE OPTION ADDENDUM
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11-May-2023
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)
Samples
(4/5)
(6)
CD74HCT21E
ACTIVE
PDIP
N
14
25
RoHS & Green
NIPDAU
N / A for Pkg Type
-55 to 125
CD74HCT21E
Samples
CD74HCT21M96
ACTIVE
SOIC
D
14
2500
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-55 to 125
HCT21M
Samples
(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
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