Part Number
    Please enter a valid full or partial manufacturer part number with a minimum of 3 letters or numbers

    51877 Search Results

    51877 Datasheets (328)

    Part ECAD Model Manufacturer Description Datasheet Type PDF PDF Size Page count
    518-77-192M16-001105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-192M16-001106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    518-77-255M16-001105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-255M16-001106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    518-77-256M16-000105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-256M16-000106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    518-77-256M20-001105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-256M20-001106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    518-77-272M20-001105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-272M20-001106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    518-77-292M20-001105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-292M20-001106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    518-77-352M26-001105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-352M26-001106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    518-77-356M26-001105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-356M26-001106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    518-77-357M19-001105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-357M19-001106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    518-77-360M19-001105
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SOLDER TAIL 1.27MM Original PDF 3
    518-77-360M19-001106
    PRECI-DIP Sockets for ICs, Transistors, Connectors, Interconnects, PGA SURFACE MOUNT 1.27MM Original PDF 3
    ...
    SF Impression Pixel

    51877 Price and Stock

    Select Manufacturer

    TE Connectivity 5745187-7

    CONN D-SUB RCPT 25POS VERT SLDR
    Distributors Part Package Stock Lead Time Min Order Qty Price Buy
    DigiKey 5745187-7 Tube 89 1
    • 1 $20.95
    • 10 $17.80
    • 100 $15.13
    • 1000 $13.51
    • 10000 $13.51
    Buy Now
    Avnet Americas 5745187-7 Tube 207 18 Weeks 10
    • 1 -
    • 10 $15.07
    • 100 $13.17
    • 1000 $13.17
    • 10000 $13.17
    Buy Now
    Newark 5745187-7 Bulk 10
    • 1 -
    • 10 $17.06
    • 100 $14.75
    • 1000 $14.75
    • 10000 $14.75
    Buy Now
    RS 5745187-7 Bulk 270
    • 1 -
    • 10 -
    • 100 -
    • 1000 $19.01
    • 10000 $16.53
    Get Quote
    Bristol Electronics () 5745187-7 153
    • 1 -
    • 10 -
    • 100 -
    • 1000 -
    • 10000 -
    Get Quote
    5745187-7 3 1
    • 1 $8.78
    • 10 $8.78
    • 100 $8.78
    • 1000 $8.78
    • 10000 $8.78
    Buy Now
    TTI 5745187-7 Tube 660 10
    • 1 -
    • 10 $13.11
    • 100 $11.65
    • 1000 $9.89
    • 10000 $9.89
    Buy Now
    Interstate Connecting Components 5745187-7
    • 1 -
    • 10 -
    • 100 -
    • 1000 $15.49
    • 10000 $15.49
    Buy Now
    Avnet Abacus () 5745187-7 24 Weeks 270
    • 1 -
    • 10 -
    • 100 -
    • 1000 -
    • 10000 -
    Buy Now
    5745187-7 8 Weeks 10
    • 1 -
    • 10 -
    • 100 -
    • 1000 -
    • 10000 -
    Buy Now

    Phoenix Contact 1518779

    CBL 3POS RCPT RA TO PLUG 1.97'
    Distributors Part Package Stock Lead Time Min Order Qty Price Buy
    DigiKey 1518779 Bulk 1
    • 1 $24.75
    • 10 $24.75
    • 100 $24.75
    • 1000 $24.75
    • 10000 $24.75
    Buy Now

    TE Connectivity 5-1877848-0

    CONN PLUG MALE 10POS SOLDER CUP
    Distributors Part Package Stock Lead Time Min Order Qty Price Buy
    DigiKey 5-1877848-0 Bulk 200
    • 1 -
    • 10 -
    • 100 -
    • 1000 $14.63
    • 10000 $14.63
    Buy Now
    Avnet Americas 5-1877848-0 Bulk 111 Weeks 200
    • 1 -
    • 10 -
    • 100 -
    • 1000 $14.01
    • 10000 $13.71
    Buy Now
    Newark 5-1877848-0 Bulk 200
    • 1 -
    • 10 -
    • 100 $16.03
    • 1000 $15.33
    • 10000 $15.33
    Buy Now
    Onlinecomponents.com 5-1877848-0
    • 1 -
    • 10 -
    • 100 $18.72
    • 1000 $14.52
    • 10000 $14.52
    Buy Now
    Interstate Connecting Components 5-1877848-0
    • 1 -
    • 10 -
    • 100 -
    • 1000 $17.21
    • 10000 $17.21
    Buy Now
    Master Electronics 5-1877848-0
    • 1 -
    • 10 -
    • 100 $18.72
    • 1000 $14.52
    • 10000 $14.52
    Buy Now
    Sager 5-1877848-0 1
    • 1 $19.50
    • 10 $18.00
    • 100 $16.25
    • 1000 $16.25
    • 10000 $16.25
    Buy Now

    TE Connectivity 5-1877845-8

    CONN PLUG MALE 5P GOLD SLDR CUP
    Distributors Part Package Stock Lead Time Min Order Qty Price Buy
    DigiKey 5-1877845-8 Bulk
    • 1 -
    • 10 -
    • 100 -
    • 1000 -
    • 10000 -
    Buy Now
    Avnet Americas 5-1877845-8 Bulk 111 Weeks 200
    • 1 -
    • 10 -
    • 100 -
    • 1000 -
    • 10000 -
    Get Quote
    Sager 5-1877845-8
    • 1 -
    • 10 -
    • 100 -
    • 1000 -
    • 10000 -
    Buy Now

    PRECI-DIP SSA 518-77-255M16-001106

    CONN SOCKET PGA 255POS GOLD
    Distributors Part Package Stock Lead Time Min Order Qty Price Buy
    DigiKey 518-77-255M16-001106 Bulk 24
    • 1 -
    • 10 -
    • 100 $134.63
    • 1000 $134.63
    • 10000 $134.63
    Buy Now
    Onlinecomponents.com 518-77-255M16-001106
    • 1 -
    • 10 $267.85
    • 100 $127.88
    • 1000 $127.88
    • 10000 $127.88
    Buy Now

    51877 Datasheets Context Search

    Catalog Datasheet Type Document Tags PDF

    CDFP3-F14

    Abstract: ACS03HMSR y4 smd transistor 5962F9670301VCC 5962F9670301VXC ACS03MS
    Contextual Info: ACS03MS TM Radiation Hardened Quad 2-Input NAND Gate with Open Drain January 1996 itle CS0 S bt adian rded ad nput ND te th en ain) utho ) eyrds terrpoion, minctor, dian rded, , d rd, L, tel, Features Pinouts • Devices QML Qualified in Accordance with MIL-PRF-38535


    Original
    ACS03MS MIL-PRF-38535 MIL-STD-1835 CDIP2-T14, 1730mm 2010mm 05A/cm CDFP3-F14 ACS03HMSR y4 smd transistor 5962F9670301VCC 5962F9670301VXC ACS03MS PDF

    HCS573DMSR

    Abstract: HCS573HMSR HCS573KMSR HCS573MS
    Contextual Info: HCS573MS Radiation Hardened Octal Transparent Latch, Three-State September 1995 Features • • • • • • • • • • • • • Pinouts 20 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-1835 CDIP2-T20, LEAD FINISH C TOP VIEW 3 Micron Radiation Hardened SOS CMOS


    Original
    HCS573MS MIL-STD-1835 CDIP2-T20, -55oC 125oC 05A/cm2 HCS573DMSR HCS573HMSR HCS573KMSR HCS573MS PDF

    Contextual Info: H S A R R HCS573MS I S S E M I C O N D U C T O R Radiation Hardened Octal Transparent Latch, Three-State September 1995 Features Pinouts 20 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-1835 CDIP2-T20, LEAD FINISH C TOP VIEW • 3 Micron Radiation Hardened SOS CMOS


    OCR Scan
    HCS573MS MIL-STD-1835 CDIP2-T20, 05A/cm2 PDF

    Contextual Info: f f ï H A R R HCTS 10MS I S S E M I C O N D U C T O R Radiation Hardened Triple 3-Input NAND Gate September 1995 Pinouts Features • 3 Micron Radiation Hardened SOS CMOS 14 LEAD CERAM IC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP M IL-STD-1835 CDIP2-T14, LEAD FINISH C


    OCR Scan
    IL-STD-1835 CDIP2-T14, 00b25fl7 HCTS10MS 05A/cm2 100nm PDF

    Contextual Info: HCS573MS Semiconductor Radiation Hardened Octal Transparent Latch, Three-State September 1995 Features Pinouts 20 LEAD CERAM IC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP M IL-STD-1835 CDIP2-T20, LEAD FINISH C TOP VIEW • 3 Micron Radiation Hardened SOS CMOS


    OCR Scan
    HCS573MS IL-STD-1835 CDIP2-T20, 05A/cm HCS573M PDF

    35x35 bga

    Abstract: C17200 C54400 540-88-084-17-400 CuSn4Pb4Zn4 MO-052 footprint 157 BGA socket 51877
    Contextual Info: PGA / BGA / PLCC SOCKETS QUICK SELECTOR CHART PGA / BGA / PLCC WWW.PRECIDIP.COM TEL +41 32 421 04 00 GRID SALES@PRECIDIP.COM 2.54 mm PGA INTERSTITIAL SOCKETS Solder tail 1.27 mm 1.27 mm BGA 1 mm PLCC SEE PAGE 156 161 165 173 Surface mount 156 161 165 166 169


    Original
    PREC68 35x35 bga C17200 C54400 540-88-084-17-400 CuSn4Pb4Zn4 MO-052 footprint 157 BGA socket 51877 PDF

    Preci-Dip Durtal SA

    Abstract: CH-2800 C17200 510-91-168-17 pga 132 packaging CuSn4Pb4Zn4 94vo fr4 Durtal SMD 2.54 90 Header 514-PP-NNNMXX-XXX148
    Contextual Info: Quick Selector Chart PGA / BGA / PLCC PGA Grid 2.54 mm BGA Interstitial 1.27 mm Sockets Solder tail 1.27 mm PLCC 1 mm See page 126 131 135 143 Surface mount 126 131 135 136 139 142 Solderless compliant press-fit Carrier Interconnect pin solder tail Interconnect pin


    Original
    CH-2800 540-PP-020-24-000-1 540-PP-028-24-000-1 540-PP-032-24-000-1 540-PP-044-24-000-1 540-PP-052-24-000-1 540-PP-068-24-000-1 540-PP-084-24-000-1 Preci-Dip Durtal SA C17200 510-91-168-17 pga 132 packaging CuSn4Pb4Zn4 94vo fr4 Durtal SMD 2.54 90 Header 514-PP-NNNMXX-XXX148 PDF

    HCS573DMSR

    Abstract: HCS573HMSR HCS573KMSR HCS573MS
    Contextual Info: HCS573MS S E M I C O N D U C T O R Radiation Hardened Octal Transparent Latch, Three-State September 1995 Features • • • • • • • • • • • • • Pinouts 20 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-1835 CDIP2-T20, LEAD FINISH C


    Original
    HCS573MS MIL-STD-1835 CDIP2-T20, -55oC 125oC 05A/cm2 HCS573DMSR HCS573HMSR HCS573KMSR HCS573MS PDF

    Contextual Info: PGA / BGA / PLCC SOCKETS 518-77-NNNMXX-XXX105 PGA 1.27 mm grid socket, Solder tail SERIES 518 Micro pin grid array sockets µPGA , with contacts placed on 1.27 mm grid, solder tail. TECHNICAL SPECS.: Insulator Glass-epoxy laminate FR4 Flammability UL 94V-O


    Original
    518-77-NNNMXX-XXX105 CuZn36Pb3 C36000) C17200) CH-2800 PDF

    Contextual Info: PGA / BGA / PLCC SOCKETS 558-10-NNNMXX-XXX101 PGA 1.27 mm grid, Interconnect pin solder tail SERIES 558 Micro pin grid array sockets µPGA , with contacts placed on 1.27 mm grid, interconnect pin. TECHNICAL SPECS.: Insulator Glass-epoxy laminate FR4 Flammability


    Original
    558-10-NNNMXX-XXX101 CuZn36Pb3 C36000) 26x26 CH-2800 PDF

    HCS374DMSR

    Abstract: HCS374HMSR HCS374KMSR HCS374MS
    Contextual Info: HCS374MS November 11, 2004 Radiation Hardened Octal D-Type Flip-Flop, Three-State, Positive Edge Triggered Features • • • • • • • • • • • • • Pinouts 3 Micron Radiation Hardened SOS CMOS Total Dose 200K RAD Si SEP Effective LET No Upsets: >100 MEV-cm2/mg


    Original
    HCS374MS -55oC 125oC 05A/cm2 HCS374 TA14304B. HCS374DMSR HCS374HMSR HCS374KMSR HCS374MS PDF

    514-PP-NNNMXX-XXX148

    Abstract: IEC60325 558-10-NNNPXX-XXX102 CuSn4Pb4Zn4 540-88-044 16x16 bga PT4642 558-10-NNNPXX-XXX103 540-88-032-24-000-1
    Contextual Info: pga/bga/plcc ソケット pga/bga/plccソケット クイックセレクタ図表 PGA/BGA/PLCCソケット WWW.PRECIDIP.COM TEL +41 32 421 04 00 ピッチ SALES@PRECIDIP.COM 2.54mm PGA 千鳥型 ソケット 半田テール 1. 27mm BGA 1. 27mm PLCC 173 1mm


    Original
    AC100Vrms/DC150V E18-084-17-400 540PLCC UL94V-0 600Vrms 514-PP-NNNMXX-XXX148 IEC60325 558-10-NNNPXX-XXX102 CuSn4Pb4Zn4 540-88-044 16x16 bga PT4642 558-10-NNNPXX-XXX103 540-88-032-24-000-1 PDF

    PCT-GF30

    Abstract: precidip C5440 SMD ic catalogue C17200 C54400 60352-5 footprint pga 84 BGA 23X23 0.8 540-88-044
    Contextual Info: PGA / BGA / PLCC SOCKETS PGA / BGA / PLCC SOCKETS QUICK SELECTOR CHART PGA / BGA / PLCC WWW.PRECIDIP.COM TEL +41 32 421 04 00 GRID SALES@PRECIDIP.COM 2.54 mm PGA INTERSTITIAL SOCKETS Solder tail 1.27 mm 1.27 mm BGA 1 mm PLCC SEE PAGE 156 161 165 173 Surface mount


    Original
    PDF

    Contextual Info: HCTSOOMS fü HARRIS S E M I C O N D U C T O R Radiation Hardened Quad 2-Input NAND Gate August 1995 Pinouts Features 3 Micron Radiation Hardened SOS CMOS 14 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-1835 CDIP2-T14 TOP VIEW Total Dose 200K RAD (Si)


    OCR Scan
    MIL-STD-1835 CDIP2-T14 PDF

    HCS374DMSR

    Abstract: HCS374HMSR HCS374KMSR HCS374MS
    Contextual Info: HCS374MS September 1995 Radiation Hardened Octal D-Type Flip-Flop, Three-State, Positive Edge Triggered Features • • • • • • • • • • • • • Pinouts 3 Micron Radiation Hardened SOS CMOS Total Dose 200K RAD Si SEP Effective LET No Upsets: >100 MEV-cm2/mg


    Original
    HCS374MS -55oC 125oC Min518770 05A/cm2 HCS374 TA14304B. HCS374DMSR HCS374HMSR HCS374KMSR HCS374MS PDF

    HCTS00D

    Abstract: HCTS00DMSR HCTS00HMSR HCTS00K HCTS00KMSR HCTS00MS
    Contextual Info: HCTS00MS TM Radiation Hardened Quad 2-Input NAND Gate August 1995 Features Pinouts • 3 Micron Radiation Hardened SOS CMOS 14 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-1835 CDIP2-T14 TOP VIEW • Total Dose 200K RAD (Si) • SEP Effective LET No Upsets: >100 MEV-cm2/mg


    Original
    HCTS00MS MIL-STD-1835 CDIP2-T14 -55oC 125oC HCTS00D HCTS00DMSR HCTS00HMSR HCTS00K HCTS00KMSR HCTS00MS PDF

    HCTS10D

    Abstract: HCTS10DMSR HCTS10HMSR HCTS10K HCTS10KMSR HCTS10MS
    Contextual Info: HCTS10MS Radiation Hardened Triple 3-Input NAND Gate September 1995 Features Pinouts • 3 Micron Radiation Hardened SOS CMOS 14 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-1835 CDIP2-T14, LEAD FINISH C TOP VIEW • Total Dose 200K RAD (Si)


    Original
    HCTS10MS MIL-STD-1835 CDIP2-T14, -55oC 125oC HCTS10D HCTS10DMSR HCTS10HMSR HCTS10K HCTS10KMSR HCTS10MS PDF

    HCS86KMSR

    Abstract: HCS86MS HCS86D HCS86DMSR HCS86HMSR HCS86K
    Contextual Info: HCS86MS Radiation Hardened Quad 2-Input Exclusive OR Gate September 1995 Features Pinouts • 3 Micron Radiation Hardened SOS CMOS 14 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-183S CDIP2-T14, LEAD FINISH C TOP VIEW • Total Dose 200K RAD (Si)


    Original
    HCS86MS MIL-STD-183S CDIP2-T14, -55oC 125oC 05A/cm2 HCS86KMSR HCS86MS HCS86D HCS86DMSR HCS86HMSR HCS86K PDF

    Contextual Info: æ HCS74MS HARRIS S E M I C O N D U C T O R Radiation Hardened Dual-D Flip-Flop with Set and Reset September 1995 Features Pinouts 3 Micron Radiation Hardened SOS CMOS 14 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-1835 CDIP2-T14, LEAD FINISH C


    OCR Scan
    HCS74MS MIL-STD-1835 CDIP2-T14, M3D2271 05A/cm2 10Oum 430E271 PDF

    PL75 plug

    Abstract: ASTM-03487 PL75-9 114403 51877
    Contextual Info: ru.u ihuiur^LO uniuiim i. D ATA CDHT lO }TIUHT M THttUOOO tOtT g HKPMET WA rD yfT UCTVMC3 DC. m o s h a l l m it • o n n n a n . g r a u a t u n o î. 2. 2.1 2 . 1.1 DESCRIPTION: CONNECTORS, PLUGS, AND RECEPTACLES,ELECTRICAL, TRIAXIAL/ TWINAXIAL, RADIO FREQUENCY TYPE, 3 SLOT BYONET COUPLING, CONCENTRIC


    OCR Scan
    PL75-9 PL75-7 BJ72/BJ77/PL75-7/ PL75 plug ASTM-03487 114403 51877 PDF

    HCTS00D

    Abstract: HCTS00DMSR HCTS00HMSR HCTS00K HCTS00KMSR HCTS00MS
    Contextual Info: HCTS00MS Radiation Hardened Quad 2-Input NAND Gate August 1995 Features Pinouts • 3 Micron Radiation Hardened SOS CMOS 14 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-1835 CDIP2-T14 TOP VIEW • Total Dose 200K RAD (Si) • SEP Effective LET No Upsets: >100 MEV-cm2/mg


    Original
    HCTS00MS MIL-STD-1835 CDIP2-T14 -55oC 125oC HCTS00D HCTS00DMSR HCTS00HMSR HCTS00K HCTS00KMSR HCTS00MS PDF

    Contextual Info: HCS374MS Semiconductor September 1995 Radiation Hardened Octal D-Type Flip-Flop, Three-State, Positive Edge Triggered Features • • • • • • • • • • • • • Pinouts 3 Micron Radiation Hardened SOS CMOS Total Dose 200K RAD Si SEP Effective LET No Upsets: >100 MEV-cm2/mg


    Original
    HCS374MS MIL-STD-1835 CDIP2-T20 HCS374MS 05A/cm2 HCS374 TA14304B. PDF

    HCS74DMSR

    Abstract: HCS74HMSR HCS74KMSR HCS74MS HCS74D
    Contextual Info: HCS74MS Radiation Hardened Dual-D Flip-Flop with Set and Reset September 1995 Features Pinouts • 3 Micron Radiation Hardened SOS CMOS 14 LEAD CERAMIC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP MIL-STD-1835 CDIP2-T14, LEAD FINISH C TOP VIEW • Total Dose 200K RAD (Si)


    Original
    HCS74MS MIL-STD-1835 CDIP2-T14, -55oC 125oC 05A/cm2 HCS74DMSR HCS74HMSR HCS74KMSR HCS74MS HCS74D PDF

    Contextual Info: HCTS04MS Semiconductor Radiation Hardened Hex Inverter August 1995 Pinouts Features • 3 Micron Radiation Hardened SOS CMOS 14 LEAD CERAM IC DUAL-IN-LINE METAL SEAL PACKAGE SBDIP M IL-STD-1835 CDIP2-T14 TOP VIEW • Total Dose 200K RAD (Si) • SEP Effective LET No Upsets: >100 MEV-cm2/mg


    OCR Scan
    HCTS04MS IL-STD-1835 CDIP2-T14 05A/cm HCTS04M PDF