Real Time Clocks

Results: 2,332
Manufacturer
ABLIC Inc.Abracon LLCAmbiq Micro, Inc.Analog Devices Inc./Maxim IntegratedAustria MicroBenchmarqCymbet CorporationDallas SemiconductorDiodes IncorporatedECS Inc.ElantecEM Microelectronic
Series
-*2-Wire™ArtasieC2C3C7C8EconoRAMLV8571ARA-4574SARA-8565SA
Packaging
BagBulkCut Tape (CT)Digi-Reel®StripTape & Reel (TR)TrayTube
Product Status
ActiveDiscontinued at Digi-KeyLast Time BuyNot For New DesignsObsolete
DigiKey Programmable
Not VerifiedVerified
Type
Binary CounterClock/CalendarClock/Calendar/SupervisorElapsed Time CounterPhantom Time ChipPortable System ControllerReal Time Clock (RTC)Temperature RecorderTime Event RecorderTimer Clock Peripheral (TCP)
Features
-AlarmAlarm, Backup Supply Charger, Leap Year, RAMAlarm, Battery Switch, Clock Output Hz-MHz, Event Input, Temperature Alarm, Timer, Trickle Charge with Charge PumpAlarm, Battery Switch, EEPROM, External Event Interrupt, Leap Year, Programmable Clock Output, RAM, Timer, Trickle ChargerAlarm, Battery Switch, Leap Year, Programmable Clock Output, Timer, Watchdog TimerAlarm, Daylight Savings, Leap Year, NVSRAM, Square Wave OutputAlarm, Daylight Savings, Leap Year, RAMAlarm, Daylight Savings, Leap Year, SRAMAlarm, Daylight Savings, Leap Year, Supervisor, Watchdog TimerAlarm, Daylight Savings, NVRAM, NVSRAM, Square Wave Output, Y2KAlarm, Daylight Savings, NVSRAM
Memory Size
1B2B2B, 43B2B, 8B3B7B8B10B16B16B, 32B31B32B
Time Format
-BinaryHH:MM:SSHH:MM:SS (12/24 hr)HH:MM:SS (24 hr)HH:MM:SS:100th (24 hr)HH:MM:SS:hhHH:MM:SS:hh (12/24 hr)HH:MM:SS:hh (24 hr)
Date Format
-BinaryYY-MM-DDYY-MM-DD-ddYYYY-MM-DD
Interface
1-Wire® and 3-Wire1-Wire® Serial2-Wire Serial3-Wire Serial3-Wire Serial, 4-Wire Serial3-Wire Serial, SPI4-Wire Serial-I2CI2C, 2-Wire SerialI2C, SerialI2C, SMBusI2C, SPIMultiplexed
Voltage - Supply
0.9V ~ 1.8V, 0.9V ~ 5.5V0.9V ~ 5.5V0.9V ~ 5.5V, 1.8V ~ 5.5V1V ~ 4.4V1V ~ 5.5V1.1V ~ 5.5V1.1V, 1.2V, 2V ~ 5.5V1.2V ~ 5.5V1.25V ~ 5.5V1.3V ~ 4.4V1.3V ~ 5.5V1.3V ~ 5.5V, 2.1V ~ 5.5V
Voltage - Supply, Battery
0.9V ~ 3.6V0.9V ~ 5.5V1V ~ 5.5V1.1V ~ 5.5V1.15V ~ 5.5V1.2V ~ 5.5V1.3V ~ 3.63V1.3V ~ 3.6V1.3V ~ 3.7V1.3V ~ 5.5V1.4V ~ 3.6V1.4V ~ 5.5V
Current - Timekeeping (Max)
0.05µA @ 2.5V ~ 5.5V0.06µA @ 2.5V ~ 5.5V0.06µA @ 3V0.08µA @ 3V0.17µA ~ 0.22µA @ 1.8V ~ 3V0.18µA @ 3V180nA @ 3V210nA @ 3V0.24µA @ 3V0.25µA @ 3V0.25µA ~ 0.27µA @ 3V ~ 5V0.25µA ~ 0.45µA @ 3V ~ 5V
Operating Temperature
-40°C ~ 105°C-40°C ~ 105°C (TA)-40°C ~ 125°C-40°C ~ 125°C (TA)-40°C ~ 85°C-40°C ~ 85°C (TA)-30°C ~ 70°C-30°C ~ 80°C-25°C ~ 70°C-20°C ~ 70°C-10°C ~ 70°C0°C ~ 70°C0°C ~ 70°C (TA)-
Mounting Type
-Surface MountSurface Mount, Wettable FlankThrough Hole
Grade
-Automotive
Qualification
-AEC-Q100AEC-Q200
Package / Case
6-SMD, J-Lead6-VBGA, FCBGA6-VFBGA, FCBGA6-WDFN Exposed Pad8-DIP (0.300", 7.62mm)8-LCC8-LSSOP (0.173", 4.40mm Width)8-SMD8-SMD, Flat Leads8-SOIC (0.154", 3.90mm Width)8-SOIC (0.173", 4.40mm Width)8-SOIC (0.173", 4.40mm Width) Exposed Pad
Supplier Device Package
6-FlipChip (1.09x1.37)6-FlipChip (2.82x2.54)6-TDFN (3x3)6-TDFN-EP (3x3)6-TSOC8-CLCC (3.2x1.5)8-DIP8-EMP8-HSOP-E8-HVSON (4x4)8-HWSON (2x3)8-LCC (1.5x3.2)
Stocking Options
Environmental Options
Media
Marketplace Product
2,332Results

Showing
of 2,332
Mfr Part #
Quantity Available
Price
Series
Package
Product Status
DigiKey Programmable
Type
Features
Memory Size
Time Format
Date Format
Interface
Voltage - Supply
Voltage - Supply, Battery
Current - Timekeeping (Max)
Operating Temperature
Mounting Type
Grade
Qualification
Package / Case
Supplier Device Package
8-SOIC
MCP7940MT-I/SN
IC RTC CLK/CALENDAR I2C 8SOIC
Microchip Technology
4,286
In Stock
1 : £0.51000
Cut Tape (CT)
3,300 : £0.45229
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM
64B
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
-
1µA @ 5.5V
-40°C ~ 85°C
Surface Mount
-
-
8-SOIC (0.154", 3.90mm Width)
8-SOIC
8-SOIC
MCP7940N-I/SN
IC RTC CLK/CALENDAR I2C 8SOIC
Microchip Technology
3,171
In Stock
100 : £0.58260
Tube
-
Tube
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM
64B
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
Automotive
AEC-Q100
8-SOIC (0.154", 3.90mm Width)
8-SOIC
8-TDFN
MCP7940MT-I/MNY
IC RTC CLK/CALENDAR I2C 8TDFN
Microchip Technology
19,552
In Stock
1 : £0.59000
Cut Tape (CT)
3,300 : £0.51745
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM
64B
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
-
1µA @ 5.5V
-40°C ~ 85°C
Surface Mount
-
-
8-WFDFN Exposed Pad
8-TDFN (2x3)
8-SOIC
MCP7940NT-I/SN
IC RTC CLK/CALENDAR I2C 8SOIC
Microchip Technology
14,447
In Stock
1 : £0.65000
Cut Tape (CT)
3,300 : £0.58262
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM
64B
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
Automotive
AEC-Q100
8-SOIC (0.154", 3.90mm Width)
8-SOIC
8-MSOP
MCP7940NT-I/MS
IC RTC CLK/CALENDAR I2C 8MSOP
Microchip Technology
27,978
In Stock
1 : £0.69000
Cut Tape (CT)
2,500 : £0.61328
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM
64B
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
Automotive
AEC-Q100
8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
8-MSOP
8-MSOP
MCP7940N-I/MS
IC RTC CLK/CALENDAR I2C 8MSOP
Microchip Technology
2,828
In Stock
1 : £0.69000
Tube
-
Tube
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM
64B
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
Automotive
AEC-Q100
8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
8-MSOP
8 SOIC
MCP7940NT-E/SN
IC RTC CLK/CALENDAR I2C 8SOIC
Microchip Technology
5,044
In Stock
1 : £0.71000
Cut Tape (CT)
3,300 : £0.62286
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM
64B
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 125°C
Surface Mount
Automotive
AEC-Q100
8-SOIC (0.154", 3.90mm Width)
8-SOIC
8-TDFN
MCP7940NT-I/MNY
IC RTC CLK/CALENDAR I2C 8TDFN
Microchip Technology
43,128
In Stock
1 : £0.73000
Cut Tape (CT)
3,300 : £0.63628
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM
64B
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
Automotive
AEC-Q100
8-WFDFN Exposed Pad
8-TDFN (2x3)
10-DFN
PCF85063ATL/1,118
IC RTC CLK/CALENDAR I2C 10DFN
NXP USA Inc.
22,134
In Stock
1 : £0.73000
Cut Tape (CT)
4,000 : £0.30915
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output
-
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
0.9V ~ 5.5V
-
0.6µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
10-XFDFN Exposed Pad
10-DFN (2.6x2.6)
8-MSOP
MCP79400T-I/MS
IC RTC CLK/CALENDAR I2C 8MSOP
Microchip Technology
7,752
In Stock
1 : £0.77000
Cut Tape (CT)
2,500 : £0.66694
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM, Unique ID
64B
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA (Typ) @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
8-MSOP
8 SOIC
PCF85063AT/AY
IC RTC CLOCK/CALENDAR I2C 8SO
NXP USA Inc.
75,899
In Stock
1 : £0.77000
Cut Tape (CT)
2,500 : £0.32834
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output
-
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
0.9V ~ 5.5V
-
0.6µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-SOIC (0.154", 3.90mm Width)
8-SO
8-TSSOP
PCF85063ATT/AJ
IC RTC CLK/CALENDAR I2C 8TSSOP
NXP USA Inc.
46,416
In Stock
1 : £0.78000
Cut Tape (CT)
2,500 : £0.33159
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output
-
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
0.9V ~ 5.5V
-
0.6µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
8-TSSOP
8-HWSON
PCF85063TP/1Z
IC RTC CLK/CALENDAR I2C 8HWSON
NXP USA Inc.
45,379
In Stock
1 : £0.78000
Cut Tape (CT)
4,000 : £0.33159
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output
-
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
0.9V ~ 5.5V
-
0.6µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-WFDFN Exposed Pad
8-HWSON (2x3)
8-SOIC
MCP79410-I/SN
IC RTC CLK/CALENDAR I2C 8SOIC
Microchip Technology
6,229
In Stock
1 : £0.80000
Tube
-
Tube
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM, Unique ID
64B, 1Kb
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-SOIC (0.154", 3.90mm Width)
8-SOIC
8-SOIC
MCP79410T-I/SN
IC RTC CLK/CALENDAR I2C 8SOIC
Microchip Technology
5,786
In Stock
1 : £0.80000
Cut Tape (CT)
3,300 : £0.69761
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM, Unique ID
64B, 1Kb
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-SOIC (0.154", 3.90mm Width)
8-SOIC
8-TSSOP
PCF85363ATT/AJ
IC RTC CLK/CALENDAR I2C 8TSSOP
NXP USA Inc.
96,749
In Stock
1 : £0.82000
Cut Tape (CT)
2,500 : £0.43907
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Watchdog Timer
64B
HH:MM:SS:hh (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
0.9V ~ 5.5V
0.9V ~ 5.5V
0.885µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
8-TSSOP
8-TSSOP
MCP79410-I/ST
IC RTC CLK/CALENDAR I2C 8TSSOP
Microchip Technology
8,089
In Stock
1 : £0.83000
Tube
-
Tube
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM, Unique ID
64B, 1Kb
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-TSSOP (0.173", 4.40mm Width)
8-TSSOP
8-MSOP
MCP79410T-I/MS
IC RTC CLK/CALENDAR I2C 8MSOP
Microchip Technology
4,556
In Stock
1 : £0.83000
Cut Tape (CT)
2,500 : £0.73785
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM, Unique ID
64B, 1Kb
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
8-MSOP
8-TDFN
MCP79410T-I/MNY
IC RTC CLK/CALENDAR I2C 8TDFN
Microchip Technology
23,935
In Stock
1 : £0.87000
Cut Tape (CT)
3,300 : £0.76660
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM, Unique ID
64B, 1Kb
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-WFDFN Exposed Pad
8-TDFN (2x3)
8 SOIC
PCF8563T/5,518
IC RTC CLOCK/CALENDAR I2C 8SO
NXP USA Inc.
20,412
In Stock
1 : £0.88000
Cut Tape (CT)
2,500 : £0.37397
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Watchdog Timer
-
HH:MM:SS (24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1V ~ 5.5V
-
0.6µA ~ 0.75µA @ 2V ~ 5V
-40°C ~ 85°C
Surface Mount
-
-
8-SOIC (0.154", 3.90mm Width)
8-SO
8-MSOP
MCP79411-I/MS
IC RTC CLK/CALENDAR I2C 8MSOP
Microchip Technology
1,660
In Stock
1 : £0.90000
Tube
-
Tube
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Square Wave Output, SRAM, Unique ID
64B, 1Kb
HH:MM:SS (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
1.8V ~ 5.5V
1.3V ~ 5.5V
1.2µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
8-MSOP
PCF85263ATL/AX
PCF85263ATL/AX
IC RTC CLK/CALENDAR I2C 10DFN
NXP USA Inc.
12,980
In Stock
1 : £0.97000
Cut Tape (CT)
4,000 : £0.41408
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, Leap Year, Watchdog Timer
-
HH:MM:SS:hh (12/24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
0.9V ~ 5.5V
0.9V ~ 5.5V
0.885µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
10-XFDFN Exposed Pad
10-DFN (2.6x2.6)
10 MSOP
MCP79510-I/MS
IC RTC CLK/CALENDAR SPI 10MSOP
Microchip Technology
9,593
In Stock
1 : £0.99000
Tube
-
Tube
Active
Not Verified
Clock/Calendar
Alarm, EEPROM, Leap Year, Square Wave Output, SRAM, Unique ID
64B
HH:MM:SS:hh (12/24 hr)
YY-MM-DD-dd
SPI
1.8V ~ 3.6V
1.3V ~ 3.6V
1µA @ 1.8V ~ 3.6V
-40°C ~ 85°C
Surface Mount
-
-
10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
10-MSOP
10 MSOP
MCP79510T-I/MS
IC RTC CLK/CALENDAR SPI 10MSOP
Microchip Technology
7,027
In Stock
1 : £0.99000
Cut Tape (CT)
2,500 : £0.86626
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Alarm, EEPROM, Leap Year, Square Wave Output, SRAM, Unique ID
64B
HH:MM:SS:hh (12/24 hr)
YY-MM-DD-dd
SPI
1.8V ~ 3.6V
1.3V ~ 3.6V
1µA @ 1.8V ~ 3.6V
-40°C ~ 85°C
Surface Mount
-
-
10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
10-MSOP
8-SOIC
BQ32002DR
IC RTC CLK/CALENDAR I2C 8SOIC
Texas Instruments
2,484
In Stock
1 : £1.53000
Cut Tape (CT)
2,500 : £0.44997
Tape & Reel (TR)
-
Tape & Reel (TR)
Cut Tape (CT)
Digi-Reel®
Active
Not Verified
Clock/Calendar
Leap Year, Square Wave Output
-
HH:MM:SS (24 hr)
YY-MM-DD-dd
I2C, 2-Wire Serial
3V ~ 3.6V
1.4V ~ 3.6V
65µA @ 3.3V
-40°C ~ 85°C
Surface Mount
-
-
8-SOIC (0.154", 3.90mm Width)
8-SOIC
Showing
of 2,332

Real Time Clocks


Real Time Clocks (RTCs) provide time and/or date information in almost any electronic device which needs to keep accurate time. The clock types are binary counter, clock/calendar/supervisor, elapsed time counter, phantom time chip, portable system controller, temperature recorder, time event recorder, and timer clock peripheral.  They contain memory sizes ranging from 2 B to 2 MB and have interface options of I2C, Parallel, Serial, SPI, 1-Wire, 2-Wire, 3-Wire, and 4-Wire.