About us Contact Us Submit BOM
RFQs(0)
English
Close Menu
View All

Please refer to the English Version as our Official Version.Return

Europe
France(Français) Germany(Deutsch) Italy(Italia) Russian(русский) Poland(polski) Czech(Čeština) Luxembourg(Lëtzebuergesch) Netherlands(Nederland) Iceland(íslenska) Hungarian(Magyarország) Spain(español) Portugal(Português) Turkey(Türk dili) Bulgaria(Български език) Ukraine(Україна) Greece(Ελλάδα) Israel(עִבְרִית) Sweden(Svenska) Finland(Svenska) Finland(Suomi) Romania(românesc) Moldova(românesc) Slovakia(Slovenská) Denmark(Dansk) Slovenia(Slovenija) Slovenia(Hrvatska) Croatia(Hrvatska) Serbia(Hrvatska) Montenegro(Hrvatska) Bosnia and Herzegovina(Hrvatska) Lithuania(lietuvių) Spain(Português) Switzerland(Deutsch) United Kingdom(English)
Asia/Pacific
Japan(日本語) Korea(한국의) Thailand(ภาษาไทย) Malaysia(Melayu) Singapore(Melayu) Vietnam(Tiếng Việt) Philippines(Pilipino)
Africa, India and Middle East
United Arab Emirates(العربية) Iran(فارسی) Tajikistan(فارسی) India(हिंदी) Madagascar(malaɡasʲ)
South America / Oceania
New Zealand(Maori) Brazil(Português) Angola(Português) Mozambique(Português)
North America
United States(English) Canada(English) Haiti(Ayiti) Mexico(español)
HomeProductsPower Supplies - (Board Mount)DC DC Converters

DC DC Converters

11,620 Products Found

Product list

1...213214215216217218219...233
Compare Image Part # Manufacturer Description Inventory ECAD Model RoHS Efficiency Number of Outputs Control Features Current - Output (Max) Voltage - Input (Min) Voltage - Output 1 Voltage - Output 2 Voltage - Output 3 Voltage - Output 4 Voltage - Isolation Approval Agency Standard Number Base Product Number Package Mounting Type Series Operating Temperature Size / Dimension Voltage - Input (Max) Type Features Applications Package / Case Supplier Device Package Power (Watts) Quantity
VE-J42-IX Vicor Corporation DC DC CONVERTER 15V 75W In stock4900 pcs 90% 1 - 5A 55V 15V - - - 3 kV - - VE-J42 Bulk Through Hole VE-J00™ (75W) -40°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 100V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 75 W
AL60A-300L-150F08 Artesyn Embedded Power DC DC CONVERTER 15V 120W In stock4970 pcs - 1 - 8A 180V 15V - - - - - - - - Through Hole AL60A (120W) - 2.40' L x 2.30' W x 0.50' H (61.0mm x 58.4mm x 12.7mm) 400V Isolated Module Remote On/Off, OTP, OVP ITE (Commercial) Module - 120 W
VE-231-EU-BM Vicor Corporation VE-231-EU-BM 48V/15V 200W In stock74 pcs - - - - - - - - - - - - VE-231 Bulk - * - - - - - - - - -
VE-J41-MX Vicor Corporation DC DC CONVERTER 12V 75W In stock5400 pcs 90% 1 - 6.25A 55V 12V - - - 3 kV - - VE-J41 Bulk Through Hole VE-J00™ (75W) -55°C ~ 100°C 2.28" L x 2.40" W x 0.50" H (57.9mm x 70.0mm x 12.7mm) 100V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 75 W
VE-J71-MY Vicor Corporation DC DC CONVERTER 12V 50W In stock53 pcs 90% 1 - 4.17A 100V 12V - - - 3 kV - - VE-J71 Bulk Through Hole VE-J00™ (50W) -55°C ~ 100°C 2.28" L x 2.40" W x 0.50" H (57.9mm x 70.0mm x 12.7mm) 375V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 50 W
CXA20-48D05 Artesyn Embedded Power DC DC CONVERTER +/-5V 20W In stock4950 pcs 84% 2 - 2A, 2A 18V 5V -5V - - 1.5 kV - - - - Through Hole CXA20 (20W) -40°C ~ 60°C 2.00" L x 1.60" W x 0.41" H (50.8mm x 40.6mm x 10.5mm) 75V Isolated Module Remote On/Off, OTP, OVP, SCP, UVLO ITE (Commercial) 8-DIP Module, 7 Leads - 20 W
MI-B20-IW Vicor Corporation MI-B20-IW 28V/5V 100W In stock4980 pcs - - - - - - - - - - - - MI-B20 Bulk - * - - - - - - - - -
LMZM33603RLRR Texas Instruments DC DC CONVERTER 1-18V In stock6731 pcs 94% 1 - 3A 4V 1 ~ 18V - - - - - - LMZM33603 Tape & Reel (TR) Surface Mount - -40°C ~ 105°C 0.35" L x 0.28" W x 0.16" H (9.0mm x 7.0mm x 4.1mm) 36V Non-Isolated PoL Module OCP, OTP, UVLO ITE (Commercial) 18-PowerBQFN Module 18-B2QFN (9x7) -
VE-26J-EY Vicor Corporation DC DC CONVERTER 36V 50W In stock4900 pcs 88% 1 - 1.39A 200V 36V - - - 3 kV - - VE-26J Bulk Through Hole VE-200™ (50W) -10°C ~ 85°C 4.60" L x 2.40" W x 0.50" H (116.8mm x 61.0mm x 12.7mm) 400V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 50 W
VE-J03-IX Vicor Corporation DC DC CONVERTER 24V 75W In stock5210 pcs 90% 1 - 3.13A 10V 24V - - - 3 kV - - VE-J03 Bulk Through Hole VE-J00™ (75W) -40°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 20V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 75 W
VI-B62-EV Vicor Corporation DC DC CONVERTER 15V 150W In stock5280 pcs 88% 1 - 10A 200V 15V - - - 3 kV - - VI-B62 Bulk Through Hole VI-200™ (150W) -10°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 400V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 150 W
PP10-24-5 TDK-Lambda Americas Inc DC DC CONVERTER 5V 10W In stock4440 pcs - 1 - 2A 18V 5V - - - - - - - - Through Hole PP (10W) -20°C ~ 71°C (With Derating) 1.85" L x 1.65" W x 0.31" H (47.0mm x 42.0mm x 8.0mm) 36V Isolated Module Remote On/Off, OVP, SCP ITE (Commercial) 4-DIP Module - 10 W
VE-221-IW Vicor Corporation DC DC CONVERTER 12V 100W In stock5020 pcs 90% 1 - 8.33A 21V 12V - - - 3 kV - - VE-221 Bulk Through Hole VE-200™ (100W) -40°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 56V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 100 W
VE-230-CU Vicor Corporation DC DC CONVERTER 5V 200W In stock5310 pcs 90% 1 - 40A 42V 5V - - - 3 kV - - VE-230 Bulk Through Hole VE-200™ (200W) -25°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 60V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 200 W
SIP20C-05S3V3 Artesyn Embedded Power DC DC CONVERTER 3.3V 20W In stock4850 pcs 90% 1 - 6A 4.5V 3.3V - - - - - - - Bulk Through Hole SIP20C (20W) -25°C ~ 85°C 2.50' L x 0.23' W x 0.55' H (63.5mm x 5.8mm x 14.0mm) 5.5V Non-Isolated PoL Module Remote On/Off, OTP, OVP, SCP, UVLO ITE (Commercial) 11-SIP Module - 20 W
AEE02A12-49 Artesyn Embedded Power DC DC CONVERTER 5V 10W In stock4430 pcs 81% 1 - 2A 9V 5V - - - 500 V - - - Bulk Through Hole AEE02 (10W) -25°C ~ 100°C 2.00" L x 1.00" W x 0.40" H (50.8mm x 25.4mm x 10.2mm) 18V Isolated Module - ITE (Commercial) 6-DIP Module - 10 W
EN5312QI Intel DC DC CONVERTER 0.6-6V 6W In stock3660 pcs 95% 1 Enable, Active High 1A 2.4V 0.6 ~ 6V - - - - - - EN5312 Tape & Reel (TR) Surface Mount Enpirion® 5300 -40°C ~ 85°C 0.20" L x 0.16" W x 0.04" H (5.0mm x 4.0mm x 1.1mm) 6.6V Non-Isolated PoL Module Remote On/Off, OCP, OTP, SCP, UVLO ITE (Commercial) 20-PowerTQFN Module 20-QFN (5x4) -
IES013ZE Bel Power Solutions DC DC CONVERTER 3.3V 20W In stock4490 pcs 83% 1 Enable, Active High 4A 36V 3.3V - - - 1.5 kV - - - Bulk Through Hole IES (20W) -40°C ~ 100°C 2.00' L x 1.00' W x 0.40' H (50.8mm x 25.4mm x 10.2mm) 72V Isolated Module Remote On/Off, OCP, OTP, OVP, SCP, UVLO ITE (Commercial) 9-DIP Module - 20 W
VI-261-CU-BM Vicor Corporation VI-261-CU-BM 300V/12V200W In stock69 pcs - - - - - - - - - - - - VI-261 Bulk - * - - - - - - - - -
VE-JNY-EY Vicor Corporation DC DC CONVERTER 3.3V 33W In stock5000 pcs 88% 1 - 10A 36V 3.3V - - - 3 kV - - VE-JNY Bulk Through Hole VE-J00™ (50W) -10°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 76V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 33 W
VE-JWM-CX Vicor Corporation DC DC CONVERTER 10V 75W In stock5370 pcs 90% 1 - 7.5A 18V 10V - - - 3 kV - - VE-JWM Bulk Through Hole VE-J00™ (75W) -25°C ~ 100°C 2.28" L x 2.40" W x 0.50" H (57.9mm x 70.0mm x 12.7mm) 36V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 75 W
LTM8023IV#PBF Linear Technology LTM8023 - 2A, 36V DC/DC Step-Dow In stock4760 pcs - 1 - 2A 3.6V 0.8 ~ 10V - - - - - - - Bulk Surface Mount µModule® -40°C ~ 85°C 0.44" L x 0.35" W x 0.11" H (11.3mm x 9.0mm x 2.9mm) 36V Non-Isolated PoL Module Adjustable Output ITE (Commercial) 50-BLGA Module 50-LGA (11.25x9) -
VE-J41-IZ Vicor Corporation DC DC CONVERTER 12V 25W In stock4080 pcs 90% 1 - 2.08A 55V 12V - - - 3 kV - - VE-J41 Bulk Through Hole VE-J00™ (25W) -40°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 100V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 25 W
PTH05010YAS Texas Instruments DC DC CONVERTER 0.55-1.8V In stock4580 pcs 88% 1 - 15A 4.5V 0.55 ~ 1.8V - - - - - - PTH05 Tray Surface Mount PTH05010Y -40°C ~ 85°C 1.37" L x 0.62" W x 0.38" H (34.8mm x 15.8mm x 9.6mm) 5.5V Non-Isolated PoL Module Remote On/Off, OCP, UVLO ITE (Commercial) 10-SMD Module - -
VI-B6V-IU Vicor Corporation DC DC CONVERTER 5.8V 200W In stock5040 pcs 90% 1 - 34.48A 200V 5.8V - - - 3 kV - - VI-B6V Bulk Through Hole VI-200™ (200W) -40°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 400V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 200 W
VE-2W3-MY Vicor Corporation DC DC CONVERTER 24V 50W In stock4420 pcs 90% 1 - 2.08A 18V 24V - - - 3 kV - - VE-2W3 Bulk Through Hole VE-200™ (50W) -55°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 36V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 50 W
AL60A-048L-050F20 Artesyn Embedded Power DC DC CONVERTER 5V 120W In stock3750 pcs - 1 - 20A 36V 5V - - - - - - - - Through Hole AL60A (120W) - 2.40' L x 2.30' W x 0.50' H (61.0mm x 58.4mm x 12.7mm) 72V Isolated Module Remote On/Off, OTP, OVP ITE (Commercial) Module - 120 W
VE-251-EY Vicor Corporation DC DC CONVERTER 12V 50W In stock5170 pcs 88% 1 - 4.17A 100V 12V - - - 3 kV - - VE-251 Bulk Through Hole VE-200™ (50W) -10°C ~ 85°C 4.60" L x 2.40" W x 0.50" H (116.8mm x 61.0mm x 12.7mm) 200V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 50 W
SQE48T20120-NDB0G-S1 Bel Power Solutions DC DC CONVERTER 12V 240W In stock4550 pcs 94.2% 1 - 20A 36V 12V - - - 2.25 kV - - SQE48T20120 Bulk Through Hole SQE48 (240W) -40°C ~ 85°C (With Derating) 2.30" L x 0.90" W x 0.44" H (58.4mm x 22.8mm x 11.2mm) 75V Isolated Module Remote On/Off, OCP, OTP, OVP, UVLO ITE (Commercial) Eighth Brick Eighth Brick 240 W
VE-JT4-EX Vicor Corporation DC DC CONVERTER 48V 75W In stock5440 pcs 88% 1 - 1.56A 66V 48V - - - 3 kV - - VE-JT4 Bulk Through Hole VE-J00™ (75W) -10°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 160V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 75 W
VE-JV4-CY Vicor Corporation DC DC CONVERTER 48V 50W In stock180 pcs 90% 1 - 1.04A 9V 48V - - - 3 kV - - VE-JV4 Bulk Through Hole VE-J00™ (50W) -25°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 36V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 50 W
VE-J53-IY Vicor Corporation DC DC CONVERTER 24V 50W In stock3730 pcs 90% 1 - 2.08A 100V 24V - - - 3 kV - - VE-J53 Bulk Through Hole VE-J00™ (50W) -40°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 200V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 50 W
IWS2412 Bel Power Solutions DC DC CONVERTER 12V 10W In stock3830 pcs - 1 - 1A 18V 12V - - - - - - - Bulk Through Hole IWS (10W) - 2.00' L x 1.00' W x 0.40' H (50.8mm x 25.4mm x 10.2mm) 36V Isolated Module - - 4-DIP Module - 10 W
VI-B64-CU-BM Vicor Corporation VI-B64-CU-BM 300V/48V In stock3630 pcs - - - - - - - - - - - - VI-B64 Bulk - * - - - - - - - - -
PKB4418PIOANB Flex Power Modules DC DC CONVERTER 1.5V 45W In stock4900 pcs 88.8% 1 Enable, Active Low 30A 36V 1.5V - - - 2.25 kV CB, CSA, IEC, TUV, UL 62368-1 PKB441 Tray Through Hole PKB 4000 (90W) -40°C ~ 120°C (With Derating) 2.30" L x 0.89" W x 0.32" H (58.4mm x 22.7mm x 8.1mm) 75V Isolated Module Adjustable Output, Remote On/Off, Remote Sense ITE (Commercial) Eighth Brick Eighth Brick 45 W
PKV5315PI Flex Power Modules DC DC CONVERTER 15V 3W In stock1539 pcs 82% 1 - 200mA 18V 15V - - - 1.5 kV CB, CSA, IEC, TUV, UL 62368-1 PKV531 Tray Through Hole PKV (3W) -40°C ~ 95°C (With Derating) 1.25" L x 0.80" W x 0.42" H (31.8mm x 20.3mm x 10.7mm) 72V Isolated Module - ITE (Commercial) 24-DIP Module, 10 Leads - 3 W
MI-J2Z-MY Vicor Corporation DC DC CONVERTER 2V 25W In stock42 pcs 90% 1 - 10A 18V 2V - - - 3 kV - - MI-J2Z Bulk Through Hole MI-J00™ (50W) -55°C ~ 85°C 2.40" L x 2.28" W x 0.50" H (61.0mm x 57.9mm x 12.7mm) 50V Isolated Module Remote On/Off, OCP, OTP, OVP ITE (Commercial) 9-DIP Module - 25 W
VE-B6M-CV Vicor Corporation DC DC CONVERTER 10V 150W In stock3640 pcs 90% 1 - 15A 200V 10V - - - 3 kV - - VE-B6M Bulk Through Hole VE-200™ (150W) -25°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 400V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 150 W
VE-220-IW Vicor Corporation DC DC CONVERTER 5V 100W In stock3920 pcs 90% 1 - 20A 21V 5V - - - 3 kV - - VE-220 Bulk Through Hole VE-200™ (100W) -40°C ~ 85°C 4.60" L x 2.40" W x 0.50" H (116.8mm x 61.0mm x 12.7mm) 56V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 100 W
VI-J61-18 Vicor Corporation VI-J61-18 300V/8V 75W In stock4810 pcs - - - - - - - - - - - - VI-J61 Bulk - * - - - - - - - - -
VE-2T3-CV Vicor Corporation DC DC CONVERTER 24V 150W In stock89 pcs 90% 1 - 6.25A 66V 24V - - - 3 kV - - VE-2T3 Bulk Through Hole VE-200™ (150W) -25°C ~ 85°C 4.60" L x 2.40" W x 0.50" H (116.8mm x 61.0mm x 12.7mm) 160V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 150 W
VE-J6F-EW Vicor Corporation DC DC CONVERTER 72V 100W In stock4290 pcs 88% 1 - 1.39A 200V 72V - - - 3 kV - - VE-J6F Bulk Through Hole VE-J00™ (100W) -10°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 400V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 100 W
VE-JT2-IZ Vicor Corporation DC DC CONVERTER 15V 25W In stock4660 pcs 90% 1 - 1.67A 66V 15V - - - 3 kV - - VE-JT2 Bulk Through Hole VE-J00™ (25W) -40°C ~ 100°C 2.28" L x 2.40" W x 0.50" H (57.9mm x 70.0mm x 12.7mm) 160V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 25 W
VE-234-EU Vicor Corporation DC DC CONVERTER 48V 200W In stock105 pcs 88% 1 - 4.17A 42V 48V - - - 3 kV - - VE-234 Bulk Through Hole VE-200™ (200W) -10°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 60V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 200 W
VI-203-05 Vicor Corporation VI-203-05 24V/24V 50W In stock3990 pcs - - - - - - - - - - - - VI-203 Bulk - * - - - - - - - - -
VE-J14-EX Vicor Corporation DC DC CONVERTER 48V 75W In stock130 pcs 88% 1 - 1.56A 21V 48V - - - 3 kV - - VE-J14 Bulk Through Hole VE-J00™ (75W) -10°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 32V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 75 W
AK80A-048L-240F10 Artesyn Embedded Power DC DC CONVERTER 24V 240W In stock4210 pcs - 1 - 10A 36V 24V - - - - - - - - Through Hole AK80A (240W) 0°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 72V Non-Isolated PoL Module Remote On/Off, OTP, OVP, SCP ITE (Commercial) Module - 240 W
MI-J53-IZ Vicor Corporation DC DC CONVERTER 24V 25W In stock3940 pcs 90% 1 - 1.04A 100V 24V - - - 3 kV - - MI-J53 Bulk Through Hole MI-J00™ (25W) -40°C ~ 85°C 2.40' L x 2.28' W x 0.50' H (61.0mm x 57.9mm x 12.7mm) 210V Isolated Module Remote On/Off, OCP, OTP, OVP ITE (Commercial) 9-DIP Module - 25 W
VE-263-EV Vicor Corporation DC DC CONVERTER 24V 150W In stock125 pcs 88% 1 - 6.25A 200V 24V - - - 3 kV - - VE-263 Bulk Through Hole VE-200™ (150W) -10°C ~ 85°C 4.60" L x 2.40" W x 0.50" H (116.8mm x 61.0mm x 12.7mm) 400V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 150 W
VE-J6J-EW Vicor Corporation DC DC CONVERTER 36V 100W In stock4220 pcs 88% 1 - 2.78A 200V 36V - - - 3 kV - - VE-J6J Bulk Through Hole VE-J00™ (100W) -10°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 400V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 100 W
1...213214215216217218219...233
Allelco
About Us
History
Certifications
Recruitment
Policies
Terms & Conditions
Privacy Policy
Cookie Policy
Services
Order Tracking
Return & Replacement
Frequently Asked Questions
Contact Us
Order
Shipping & Delivering
Payment Methods
My Account
The BlogsHot PartsChange LanguageNewsSite map
Contact Us
Headquarters Address:
Room C 13/F Harvard Commercial Building
105-111 Thomson Road Wan Chai
HongKong
Service Tel: +852-91464856
Service Email: info@allelco.com
Follow us
Copyright © 2012-2023 AllelcoElec.com. All rights reserved.
0 RFQ
Shopping cart (0 Items)
It is empty.
Submit RFQ
Compare List (0 Items)
It is empty.
Feedback

Your feedback matters! At Allelco, we value the user experience and strive to improve it constantly.
Please share your comments with us via our feedback form, and we'll respond promptly.
Thank you for choosing Allelco.

Subject
E-mail
Comments
Captcha
Drag or click to upload file
Upload File
types: .xls, .xlsx, .doc, .docx, .jpg, .png and .pdf.
Max file size: 10MB