|
|
32-bit Microcontrollers - MCU 32BIT MCU RX111 64K/10K QFP64
- R5F51113AGFM#3A
- Renesas Electronics
-
1:
$3.34
-
790In Stock
|
Mouser Part No
968-R5F51113AGFM3A
|
Renesas Electronics
|
32-bit Microcontrollers - MCU 32BIT MCU RX111 64K/10K QFP64
|
|
790In Stock
|
|
|
$3.34
|
|
|
$2.51
|
|
|
$2.30
|
|
|
$2.01
|
|
|
View
|
|
|
$1.93
|
|
|
$1.83
|
|
|
$1.73
|
|
Min.: 1
Mult.: 1
|
|
|
RX111
|
SMD/SMT
|
LFQFP-64
|
RX
|
64 kB
|
10 kB
|
32 bit
|
12 bit
|
32 MHz
|
46 I/O
|
1.8 V
|
3.6 V
|
- 40 C
|
+ 105 C
|
|
Tray
|
|
|
|
32-bit Microcontrollers - MCU 8KB RAM 79 Power microMIPS
- PIC32MM0064GPL020-I/SS
- Microchip Technology
-
1:
$1.81
-
577In Stock
|
Mouser Part No
579-MM0064GPL020ISS
|
Microchip Technology
|
32-bit Microcontrollers - MCU 8KB RAM 79 Power microMIPS
|
|
577In Stock
|
|
|
$1.81
|
|
|
$1.78
|
|
|
$1.60
|
|
|
$1.48
|
|
Min.: 1
Mult.: 1
|
|
|
PIC32MMxxxxGPL
|
SMD/SMT
|
SSOP-20
|
MIPS32 microAptiv UC
|
64 kB
|
8 kB
|
32 bit
|
10 bit/12 bit
|
25 MHz
|
16 I/O
|
2 V
|
3.6 V
|
- 40 C
|
+ 85 C
|
AEC-Q100
|
Tube
|
|
|
|
32-bit Microcontrollers - MCU 64KB Flash, 16KB RAM, 79 CoreMark at 25MHz, Low Power microMIPS
- PIC32MM0064GPM028-I/ML
- Microchip Technology
-
1:
$2.22
-
366In Stock
|
Mouser Part No
579-MM0064GPM028IML
|
Microchip Technology
|
32-bit Microcontrollers - MCU 64KB Flash, 16KB RAM, 79 CoreMark at 25MHz, Low Power microMIPS
|
|
366In Stock
|
|
|
$2.22
|
|
|
$2.06
|
|
|
$2.01
|
|
|
$2.00
|
|
Min.: 1
Mult.: 1
|
|
|
PIC32MMxxxxGPM
|
SMD/SMT
|
QFN-28
|
MIPS32 microAptiv UC
|
64 kB
|
16 kB
|
32 bit
|
10 bit/12 bit
|
25 MHz
|
21 I/O
|
2 V
|
3.6 V
|
- 40 C
|
+ 85 C
|
AEC-Q100
|
Tube
|
|
|
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wi th 100 MHz FPU TMU
- F280023CPNSR
- Texas Instruments
-
1:
$7.92
-
1,975In Stock
|
Mouser Part No
595-F280023CPNSR
|
Texas Instruments
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wi th 100 MHz FPU TMU
|
|
1,975In Stock
|
|
|
$7.92
|
|
|
$6.12
|
|
|
$5.40
|
|
|
$5.18
|
|
|
View
|
|
|
$4.48
|
|
|
$4.79
|
|
|
$4.48
|
|
|
Quote
|
|
Min.: 1
Mult.: 1
:
1,000
|
|
|
TMS320F280023C
|
SMD/SMT
|
LQFP-80
|
C28x
|
64 kB
|
24 kB
|
32 bit
|
2 x 12 bit
|
100 MHz
|
39 I/O
|
2.8 V
|
3.63 V
|
- 40 C
|
+ 125 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wi th 100 MHz 64 KB fl A 595-TMS320F2806NMFS
- TMS320F2806NMFA
- Texas Instruments
-
1:
$28.31
-
184In Stock
|
Mouser Part No
595-TMS320F2806NMFA
|
Texas Instruments
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wi th 100 MHz 64 KB fl A 595-TMS320F2806NMFS
|
|
184In Stock
|
|
|
$28.31
|
|
|
$22.78
|
|
|
$20.57
|
|
|
$18.49
|
|
|
View
|
|
|
$18.48
|
|
|
Quote
|
|
Min.: 1
Mult.: 1
|
|
|
TMS320F2806
|
SMD/SMT
|
NFBGA-100
|
C28x
|
64 kB
|
20 kB
|
32 bit
|
12 bit
|
100 MHz
|
35 I/O
|
1.71 V
|
1.89 V
|
- 40 C
|
+ 85 C
|
|
Tray
|
|
|
|
32-bit Microcontrollers - MCU 64KB Flash, 8KB RAM, 79 CoreMark at 25MHz, Low Power microMIPS
- PIC32MM0064GPL028-E/SP
- Microchip Technology
-
1:
$2.02
-
422In Stock
|
Mouser Part No
579-MM0064GPL028ESP
|
Microchip Technology
|
32-bit Microcontrollers - MCU 64KB Flash, 8KB RAM, 79 CoreMark at 25MHz, Low Power microMIPS
|
|
422In Stock
|
|
Min.: 1
Mult.: 1
|
|
|
|
SMD/SMT
|
|
MIPS32 microAptiv UC
|
64 kB
|
8 kB
|
32 bit
|
10 bit/12 bit
|
25 MHz
|
22 I/O
|
2 V
|
3.6 V
|
- 40 C
|
+ 125 C
|
AEC-Q100
|
Tube
|
|
|
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wi th 100 MHz FPU TMU
- F280023CPMSR
- Texas Instruments
-
1:
$7.04
-
1,785In Stock
|
Mouser Part No
595-F280023CPMSR
|
Texas Instruments
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wi th 100 MHz FPU TMU
|
|
1,785In Stock
|
|
|
$7.04
|
|
|
$5.41
|
|
|
$4.76
|
|
|
$4.56
|
|
|
$4.11
|
|
|
View
|
|
|
$4.22
|
|
|
$4.01
|
|
|
Quote
|
|
Min.: 1
Mult.: 1
:
1,000
|
|
|
TMS320F280023C
|
SMD/SMT
|
LQFP-64
|
C28x
|
64 kB
|
24 kB
|
32 bit
|
2 x 12 bit
|
100 MHz
|
26 I/O
|
2.8 V
|
3.63 V
|
- 40 C
|
+ 125 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wi th 100 MHz FPU TMU
- F280023CPTSR
- Texas Instruments
-
1:
$6.44
-
3,774In Stock
|
Mouser Part No
595-F280023CPTSR
|
Texas Instruments
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wi th 100 MHz FPU TMU
|
|
3,774In Stock
|
|
|
$6.44
|
|
|
$4.94
|
|
|
$4.34
|
|
|
$4.15
|
|
|
$3.47
|
|
|
View
|
|
|
$3.84
|
|
|
$3.45
|
|
Min.: 1
Mult.: 1
:
1,000
|
|
|
TMS320F280023C
|
SMD/SMT
|
LQFP-48
|
C28x
|
64 kB
|
24 kB
|
32 bit
|
2 x 12 bit
|
100 MHz
|
16 I/O
|
3.3 V
|
3.3 V
|
- 40 C
|
+ 125 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU Automotive C2000 32 -bit MCU with 100 MH
- F280023PNQR
- Texas Instruments
-
1:
$7.65
-
803In Stock
|
Mouser Part No
595-F280023PNQR
|
Texas Instruments
|
32-bit Microcontrollers - MCU Automotive C2000 32 -bit MCU with 100 MH
|
|
803In Stock
|
|
|
$7.65
|
|
|
$5.91
|
|
|
$5.21
|
|
|
$4.99
|
|
|
$4.40
|
|
|
View
|
|
|
$4.72
|
|
|
$4.35
|
|
|
Quote
|
|
Min.: 1
Mult.: 1
:
1,000
|
|
|
TMS320F280023
|
SMD/SMT
|
LQFP-80
|
C28x
|
64 kB
|
24 kB
|
32 bit
|
2 x 12 bit
|
100 MHz
|
39 I/O
|
2.8 V
|
3.63 V
|
- 40 C
|
+ 125 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU Automotive C2000 32 -bit MCU with 100 MH
- F280023PTQR
- Texas Instruments
-
1:
$7.29
-
1,688In Stock
|
Mouser Part No
595-F280023PTQR
|
Texas Instruments
|
32-bit Microcontrollers - MCU Automotive C2000 32 -bit MCU with 100 MH
|
|
1,688In Stock
|
|
|
$7.29
|
|
|
$5.47
|
|
|
$4.95
|
|
|
$4.52
|
|
|
View
|
|
|
$3.54
|
|
|
$4.40
|
|
|
$4.00
|
|
|
$3.54
|
|
|
Quote
|
|
Min.: 1
Mult.: 1
:
1,000
|
|
|
TMS320F280023
|
SMD/SMT
|
LQFP-48
|
C28x
|
64 kB
|
24 kB
|
32 bit
|
2 x 12 bit
|
100 MHz
|
16 I/O
|
2.8 V
|
3.63 V
|
- 40 C
|
+ 125 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU 32BIT MCU RX23T 64K/12K QFP48
- R5F523T3AGFL#30
- Renesas Electronics
-
1:
$3.77
-
443In Stock
|
Mouser Part No
968-R5F523T3AGFL30
|
Renesas Electronics
|
32-bit Microcontrollers - MCU 32BIT MCU RX23T 64K/12K QFP48
|
|
443In Stock
|
|
|
$3.77
|
|
|
$2.84
|
|
|
$2.61
|
|
|
$2.35
|
|
|
View
|
|
|
$2.20
|
|
|
$2.14
|
|
|
$2.11
|
|
|
$2.09
|
|
|
$1.98
|
|
Min.: 1
Mult.: 1
|
|
|
RX23T
|
SMD/SMT
|
LFQFP-48
|
RX
|
64 kB
|
12 kB
|
32 bit
|
12 bit
|
40 MHz
|
37 I/O
|
2.7 V
|
5.5 V
|
- 40 C
|
+ 105 C
|
|
Tray
|
|
|
|
32-bit Microcontrollers - MCU 32B MCU 64KB FL 16KB RAM 40MHz 28Pin
- PIC32MX130F064B-V/ML
- Microchip Technology
-
1:
$3.61
-
244In Stock
|
Mouser Part No
579-32MX130F064BVML
|
Microchip Technology
|
32-bit Microcontrollers - MCU 32B MCU 64KB FL 16KB RAM 40MHz 28Pin
|
|
244In Stock
|
|
|
$3.61
|
|
|
$3.33
|
|
|
$3.00
|
|
Min.: 1
Mult.: 1
|
|
|
PIC32MX1xx
|
SMD/SMT
|
QFN-28
|
MIPS32 M4K
|
64 kB
|
16 kB
|
32 bit
|
10 bit
|
40 MHz
|
21 I/O
|
2.3 V
|
3.6 V
|
- 40 C
|
+ 105 C
|
|
Tube
|
|
|
|
32-bit Microcontrollers - MCU 32BIT MCU RX130 64K HWQFN48 -40/+85C
- R5F51303ADNE#20
- Renesas Electronics
-
1:
$3.44
-
850In Stock
|
Mouser Part No
968-R5F51303ADNE#20
|
Renesas Electronics
|
32-bit Microcontrollers - MCU 32BIT MCU RX130 64K HWQFN48 -40/+85C
|
|
850In Stock
|
|
|
$3.44
|
|
|
$2.59
|
|
|
$2.37
|
|
|
$2.14
|
|
|
View
|
|
|
$1.97
|
|
|
$1.91
|
|
|
$1.90
|
|
|
$1.79
|
|
Min.: 1
Mult.: 1
|
|
|
RX130
|
SMD/SMT
|
HWQFN-48
|
RX
|
64 kB
|
10 kB
|
32 bit
|
12 bit
|
32 MHz
|
38 I/O
|
1.8 V
|
5.5 V
|
- 40 C
|
+ 85 C
|
|
Tray
|
|
|
|
32-bit Microcontrollers - MCU 32BIT MCU RX140 64KB Flash LFQFP-64pin
- R5F51403ADFM#30
- Renesas Electronics
-
1:
$2.94
-
775In Stock
|
Mouser Part No
968-R5F51403ADFM#30
|
Renesas Electronics
|
32-bit Microcontrollers - MCU 32BIT MCU RX140 64KB Flash LFQFP-64pin
|
|
775In Stock
|
|
|
$2.94
|
|
|
$2.20
|
|
|
$1.90
|
|
|
$1.76
|
|
|
View
|
|
|
$1.71
|
|
|
$1.60
|
|
|
$1.59
|
|
|
$1.50
|
|
Min.: 1
Mult.: 1
|
|
|
RX140
|
SMD/SMT
|
LFQFP-64
|
RXv2
|
64 kB
|
16 kB
|
32 bit
|
12 bit
|
48 MHz
|
53 I/O
|
1.8 V
|
5.5 V
|
- 40 C
|
+ 85 C
|
|
Tray
|
|
|
|
32-bit Microcontrollers - MCU 32BIT MCU RX71M 2048K/512K QFP176
- R5F571MFCDFC#10
- Renesas Electronics
-
1:
$22.26
-
288In Stock
|
Mouser Part No
968-R5F571MFCDFC#10
|
Renesas Electronics
|
32-bit Microcontrollers - MCU 32BIT MCU RX71M 2048K/512K QFP176
|
|
288In Stock
|
|
|
$22.26
|
|
|
$17.78
|
|
|
$15.99
|
|
|
$15.43
|
|
|
View
|
|
|
$14.11
|
|
|
$14.10
|
|
|
$13.99
|
|
|
Quote
|
|
Min.: 1
Mult.: 1
|
|
|
RX71M
|
SMD/SMT
|
LFQFP-176
|
RXv2
|
64 kB
|
512 kB
|
32 bit
|
12 bit
|
240 MHz
|
|
2.7 V
|
3.6 V
|
- 40 C
|
+ 85 C
|
|
Tray
|
|
|
|
32-bit Microcontrollers - MCU 32BIT MCU RX130 64K/10K QFP80
- R5F51303ADFN#30
- Renesas Electronics
-
1:
$3.84
-
504In Stock
|
Mouser Part No
968-R5F51303ADFN#30
|
Renesas Electronics
|
32-bit Microcontrollers - MCU 32BIT MCU RX130 64K/10K QFP80
|
|
504In Stock
|
|
|
$3.84
|
|
|
$2.90
|
|
|
$2.66
|
|
|
$2.35
|
|
|
View
|
|
|
$2.22
|
|
|
$2.14
|
|
|
$2.02
|
|
Min.: 1
Mult.: 1
|
|
|
RX130
|
SMD/SMT
|
LFQFP-80
|
RX
|
64 kB
|
10 kB
|
32 bit
|
12 bit
|
32 MHz
|
68 I/O
|
1.8 V
|
5.5 V
|
- 40 C
|
+ 85 C
|
|
Tray
|
|
|
|
32-bit Microcontrollers - MCU 100PINS 64KB 32KBRM 80MHz USB CAN 4DMA
- PIC32MX564F064L-I/PT
- Microchip Technology
-
1:
$6.55
-
238In Stock
|
Mouser Part No
579-32MX564F064LIPT
|
Microchip Technology
|
32-bit Microcontrollers - MCU 100PINS 64KB 32KBRM 80MHz USB CAN 4DMA
|
|
238In Stock
|
|
Min.: 1
Mult.: 1
|
|
|
PIC32MX5xx
|
SMD/SMT
|
TQFP-100
|
MIPS32 M4K
|
64 kB
|
32 kB
|
32 bit
|
10 bit
|
80 MHz
|
85 I/O
|
2.3 V
|
3.6 V
|
- 40 C
|
+ 85 C
|
|
Tray
|
|
|
|
32-bit Microcontrollers - MCU UC3C 64K FLASH 16K SRAM
- AT32UC3C164C-AUR
- Microchip Technology
-
1:
$10.96
-
95In Stock
|
Mouser Part No
556-AT32UC3C164C-AUR
|
Microchip Technology
|
32-bit Microcontrollers - MCU UC3C 64K FLASH 16K SRAM
|
|
95In Stock
|
|
|
$10.96
|
|
|
$10.58
|
|
|
$9.02
|
|
Min.: 1
Mult.: 1
:
1,000
|
|
|
AT32UC3C1
|
SMD/SMT
|
TQFP-100
|
AVR
|
64 kB
|
16 kB
|
32 bit
|
12 bit
|
66 MHz
|
81 I/O
|
3 V
|
5.5 V
|
- 40 C
|
+ 85 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU 64KB Flash, 8KB RAM, 79 CoreMark at 25MHz, Low Power microMIPS
- PIC32MM0064GPL020-E/ML
- Microchip Technology
-
1:
$2.05
-
442In Stock
|
Mouser Part No
579-MM0064GPL020EML
|
Microchip Technology
|
32-bit Microcontrollers - MCU 64KB Flash, 8KB RAM, 79 CoreMark at 25MHz, Low Power microMIPS
|
|
442In Stock
|
|
Min.: 1
Mult.: 1
|
|
|
|
SMD/SMT
|
QFN-20
|
MIPS32 microAptiv UC
|
64 kB
|
8 kB
|
32 bit
|
10 bit/12 bit
|
25 MHz
|
16 I/O
|
2 V
|
3.6 V
|
- 40 C
|
+ 125 C
|
AEC-Q100
|
Tube
|
|
|
|
32-bit Microcontrollers - MCU 32B MCU 64KB FL 16KB RAM 40MHz 28Pin
- PIC32MX130F064BT-I/ML
- Microchip Technology
-
1:
$3.45
-
348In Stock
|
Mouser Part No
579-32MX130F064BTIML
|
Microchip Technology
|
32-bit Microcontrollers - MCU 32B MCU 64KB FL 16KB RAM 40MHz 28Pin
|
|
348In Stock
|
|
|
$3.45
|
|
|
$3.36
|
|
|
$2.88
|
|
|
$2.88
|
|
Min.: 1
Mult.: 1
:
1,600
|
|
|
PIC32MX1xx
|
SMD/SMT
|
QFN-28
|
MIPS32 M4K
|
64 kB
|
16 kB
|
32 bit
|
10 bit
|
40 MHz
|
21 I/O
|
2.3 V
|
3.6 V
|
- 40 C
|
+ 85 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU 64KB Flash, 16KB RAM, 79 CoreMark at 25MHz, Low Power microMIPS
- PIC32MM0064GPM048-I/M4
- Microchip Technology
-
1:
$2.54
-
356In Stock
|
Mouser Part No
579-MM0064GPM048IM4
|
Microchip Technology
|
32-bit Microcontrollers - MCU 64KB Flash, 16KB RAM, 79 CoreMark at 25MHz, Low Power microMIPS
|
|
356In Stock
|
|
|
$2.54
|
|
|
$2.31
|
|
|
$2.11
|
|
Min.: 1
Mult.: 1
|
|
|
PIC32MMxxxxGPM
|
SMD/SMT
|
UQFN-48
|
MIPS32 microAptiv UC
|
64 kB
|
16 kB
|
32 bit
|
10 bit/12 bit
|
25 MHz
|
38 I/O
|
2 V
|
3.6 V
|
- 40 C
|
+ 85 C
|
AEC-Q100
|
Tube
|
|
|
|
32-bit Microcontrollers - MCU C2000 32-bit MCU with 160 MHz, 64KB flash, FPU, PGA
- F28E120SBTPTR
- Texas Instruments
-
1:
$2.67
-
700In Stock
-
New Product
|
Mouser Part No
595-F28E120SBTPTR
New Product
|
Texas Instruments
|
32-bit Microcontrollers - MCU C2000 32-bit MCU with 160 MHz, 64KB flash, FPU, PGA
|
|
700In Stock
|
|
|
$2.67
|
|
|
$1.73
|
|
|
$1.54
|
|
|
$1.27
|
|
|
$0.921
|
|
|
View
|
|
|
$1.20
|
|
|
$1.05
|
|
|
$0.908
|
|
|
$0.892
|
|
Min.: 1
Mult.: 1
:
1,000
|
|
|
F28E120SB
|
SMD/SMT
|
LQFP-48
|
ARM Cortex M7
|
64 kB
|
16 kB
|
32 bit
|
12 bit
|
160 MHz
|
27 I/O
|
2.8 V
|
3.63 V
|
- 40 C
|
+ 125 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wit h 100 MHz FPU TMU
- F280023CPTSRG4
- Texas Instruments
-
1:
$8.61
-
1,000In Stock
-
New Product
|
Mouser Part No
595-F280023CPTSRG4
New Product
|
Texas Instruments
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wit h 100 MHz FPU TMU
|
|
1,000In Stock
|
|
|
$8.61
|
|
|
$6.01
|
|
|
$5.73
|
|
|
$4.98
|
|
|
$4.26
|
|
|
View
|
|
|
$4.76
|
|
|
$4.33
|
|
|
$4.14
|
|
|
Quote
|
|
Min.: 1
Mult.: 1
:
1,000
|
|
|
TMS320F280023C
|
SMD/SMT
|
LQFP-48
|
DSP
|
64 kB
|
24 kB
|
32 bit
|
12 bit
|
100 MHz
|
20 I/O
|
2.8 V
|
3.63 V
|
- 40 C
|
+ 125 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wit h 100-MHz FPU TMU
- F280023PTSRG4
- Texas Instruments
-
1:
$7.55
-
1,000In Stock
-
New Product
|
Mouser Part No
595-F280023PTSRG4
New Product
|
Texas Instruments
|
32-bit Microcontrollers - MCU C2000 32-bit MCU wit h 100-MHz FPU TMU
|
|
1,000In Stock
|
|
|
$7.55
|
|
|
$5.55
|
|
|
$5.18
|
|
|
$4.54
|
|
|
$3.54
|
|
|
View
|
|
|
$4.31
|
|
|
$3.87
|
|
|
$3.47
|
|
|
Quote
|
|
Min.: 1
Mult.: 1
:
1,000
|
|
|
TMS320F280023
|
SMD/SMT
|
LQFP-48
|
DSP
|
64 kB
|
24 kB
|
32 bit
|
12 bit
|
100 MHz
|
20 I/O
|
2.8 V
|
3.63 V
|
- 40 C
|
+ 125 C
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
32-bit Microcontrollers - MCU 32-bit 200MHz MCU, DP-FPU, 64K Flash, 16K RAM, 40Msps 12-bit ADCs, Op Amps, Comp
- PIC32AK6416GC41036-I/M7
- Microchip Technology
-
1:
$1.76
-
756In Stock
-
New Product
|
Mouser Part No
579-K6416GC41036IM7
New Product
|
Microchip Technology
|
32-bit Microcontrollers - MCU 32-bit 200MHz MCU, DP-FPU, 64K Flash, 16K RAM, 40Msps 12-bit ADCs, Op Amps, Comp
|
|
756In Stock
|
|
Min.: 1
Mult.: 1
|
|
|
|
SMD/SMT
|
VQFN-36
|
|
64 kB
|
16 kB
|
32 bit
|
12 bit
|
200 MHz
|
27 I/O
|
3 V
|
3.6 V
|
- 40 C
|
+ 85 C
|
|
Tube
|
|
South Africa