모두보기

영어판을 공식 버전으로 해주세요돌아가기

유럽
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)
아시아 태평양
Japan(日本語) Korea(한국의) Thailand(ภาษาไทย) Malaysia(Melayu) Singapore(Melayu) Vietnam(Tiếng Việt) Philippines(Pilipino)
아프리카, 인도 및 중동
United Arab Emirates(العربية) Iran(فارسی) Tajikistan(فارسی) India(हिंदी) Madagascar(malaɡasʲ)
남아메리카 / 오세아니아
New Zealand(Maori) Brazil(Português) Angola(Português) Mozambique(Português)
북아메리카
United States(English) Canada(English) Haiti(Ayiti) Mexico(español)
제품 센터전원 공급 장치-보드 장착dc dc 컨버터

dc dc 컨버터

11,620 제품이 발견되었습니다

제품 목록

1...203204205206207208209...233
비교 그림 부분 # 제조사 기술 재고 ECAD 모델 RoHS 능률 출력 수 제어 기능 전류 - 출력 (최대) 전압 - 입력 (최소) 전압 - 출력 1 전압 - 출력 2 전압 - 출력 3 전압 - 출력 (4) 전압 - 분리 기본 제품 번호 패키지 실장 형 연속 작동 온도 크기 / 치수 전압 - 입력 (최대) 유형 풍모 응용 프로그램 패키지 / 케이스 제조업체 장치 패키지 전력 (W) 수량
VE-242-MW Vicor Corporation DC DC CONVERTER 15V 100W 유품4780 pcs 90% 1 - 6.67A 55V 15V - - - 3 kV VE-242 Bulk Through Hole VE-200™ (100W) -55°C ~ 85°C 4.60" L x 2.40" W x 0.50" H (116.8mm x 61.0mm x 12.7mm) 100V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 100 W
VE-223-EX Vicor Corporation DC DC CONVERTER 24V 75W 유품4430 pcs 88% 1 - 3.13A 21V 24V - - - 3 kV VE-223 Bulk Through Hole VE-200™ (75W) -10°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 - 75 W
VE-J43-MW Vicor Corporation DC DC CONVERTER 24V 100W 유품5010 pcs 90% 1 - 4.17A 55V 24V - - - 3 kV VE-J43 Bulk Through Hole VE-J00™ (100W) -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 - 100 W
PM10-24D15 TDK-Lambda Americas Inc DC DC CONVERTER +/-15V 10W 유품3700 pcs - 2 - 330mA, 330mA 18V 15V -15V - - 700 V - - Through Hole PM -40°C ~ 70°C 2.00" L x 1.00" W x 0.33" H (50.8mm x 25.4mm x 8.5mm) 36V Isolated Module OVP, SCP ITE (Commercial) 5-DIP Module - 10 W
VE-203-MX Vicor Corporation DC DC CONVERTER 24V 75W 유품4980 pcs 90% 1 - 3.13A 10V 24V - - - 3 kV VE-203 Bulk Through Hole VE-200™ (75W) -55°C ~ 85°C 4.60" L x 2.40" W x 0.50" H (116.8mm x 61.0mm x 12.7mm) 20V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 75 W
VE-J14-CY Vicor Corporation DC DC CONVERTER 48V 50W 유품4580 pcs 90% 1 - 1.04A 21V 48V - - - 3 kV VE-J14 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) 32V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 50 W
CC025ABK-M ABB Power Electronics Inc. DC DC CONVERTER 5V +/-12V 25W 유품4580 pcs 82% 3 Enable, Active High 5A, 1A, 1A 18V 5V 12V -12V - 500 V - Bulk Through Hole CC025 (25W) -40°C ~ 100°C 2.80' L x 2.40' W x 0.50' H (71.1mm x 61.0mm x 12.7mm) 36V Isolated Module Remote On/Off, OCP, OVP ITE (Commercial) 10-DIP Module - 25 W
VE-J12-EX Vicor Corporation DC DC CONVERTER 15V 75W 유품127 pcs 88% 1 - 5A 21V 15V - - - 3 kV VE-J12 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
VE-214-MW Vicor Corporation DC DC CONVERTER 48V 100W 유품5180 pcs 90% 1 - 2.08A 21V 48V - - - 3 kV VE-214 Bulk Through Hole VE-200™ (100W) -55°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 32V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 100 W
VI-BWL-CW Vicor Corporation DC DC CONVERTER 28V 100W 유품4970 pcs 90% 1 - 3.57A 18V 28V - - - 3 kV VI-BWL Bulk Through Hole VI-200™ (100W) -25°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 - 100 W
VE-224-EW Vicor Corporation DC DC CONVERTER 48V 100W 유품4440 pcs 88% 1 - 2.08A 21V 48V - - - 3 kV VE-224 Bulk Through Hole VE-200™ (100W) -10°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-J6Y-MX Vicor Corporation DC DC CONVERTER 3.3V 50W 유품4680 pcs 90% 1 - 15A 200V 3.3V - - - 3 kV VE-J6Y 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) 400V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 50 W
MI-J60-MY Vicor Corporation DC DC CONVERTER 5V 50W 유품39 pcs 90% 1 - 10A 125V 5V - - - 3 kV MI-J60 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) 400V Isolated Module Remote On/Off, OCP, OTP, OVP ITE (Commercial) 9-DIP Module - 50 W
JFW100A1 ABB Power Electronics Inc. DC DC CONVERTER 5V 100W 유품4170 pcs 84% 1 Enable, Active Low 20A 36V 5V - - - 1.5 kV - Bulk Through Hole JFW (100W) -40°C ~ 100°C 2.40" L x 2.28" W x 0.50" H (61.0mm x 57.9mm x 12.7mm) 75V Isolated Module Remote On/Off, OCP, OTP, OVP ITE (Commercial) Module - 100 W
VE-J24-EZ Vicor Corporation DC DC CONVERTER 48V 25W 유품5230 pcs 88% 1 - 521mA 21V 48V - - - 3 kV VE-J24 Bulk Through Hole VE-J00™ (25W) -10°C ~ 100°C 2.28' L x 2.40' W x 0.50' H (57.9mm x 70.0mm x 12.7mm) 56V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 25 W
VI-262-27 Vicor Corporation VI-262-27 300V/20V 200W S 유품4550 pcs - - - - - - - - - - VI-262 Bulk - * - - - - - - - - -
LW010BK ABB Power Electronics Inc. DC DC CONVERTER +/-12V 10W 유품5190 pcs 80% 2 - 420mA, 420mA 36V 12V -12V - - 1.5 kV - Bulk Through Hole LW010 (10W) -40°C ~ 105°C 2.00" L x 1.00" W x 0.40" H (50.8mm x 25.4mm x 10.2mm) 75V Isolated Module OCP, OVP, UVLO ITE (Commercial) 6-DIP Module - 10 W
VE-263-CW Vicor Corporation DC DC CONVERTER 24V 100W 유품78 pcs 90% 1 - 4.17A 200V 24V - - - 3 kV VE-263 Bulk Through Hole VE-200™ (100W) -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 - 100 W
VE-J54-IZ Vicor Corporation DC DC CONVERTER 48V 25W 유품4530 pcs 90% 1 - 521mA 100V 48V - - - 3 kV VE-J54 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) 200V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 25 W
VE-263-MW Vicor Corporation DC DC CONVERTER 24V 100W 유품43 pcs 90% 1 - 4.17A 200V 24V - - - 3 kV VE-263 Bulk Through Hole VE-200™ (100W) -55°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 - 100 W
X15-48S03 TDK-Lambda Americas Inc DC DC CONVERTER 3.3V 10W 유품4610 pcs 79% 1 - 3A 36V 3.3V - - - 1.5 kV - - Through Hole X15 (15W) -40°C ~ 105°C (With Derating) 2.00" L x 1.00" W x 0.38" H (50.8mm x 25.4mm x 9.7mm) 75V Isolated Module Remote On/Off, OVP, SCP ITE (Commercial) 6-DIP Module - 10 W
VE-243-MV Vicor Corporation DC DC CONVERTER 24V 150W 유품5010 pcs 90% 1 - 6.25A 55V 24V - - - 3 kV VE-243 Bulk Through Hole VE-200™ (150W) -55°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 100V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 150 W
VE-2T0-MY Vicor Corporation DC DC CONVERTER 5V 50W 유품5170 pcs 90% 1 - 10A 66V 5V - - - 3 kV VE-2T0 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) 160V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 50 W
VE-J51-MW Vicor Corporation DC DC CONVERTER 12V 100W 유품3720 pcs 90% 1 - 8.33A 100V 12V - - - 3 kV VE-J51 Bulk Through Hole VE-J00™ (100W) -55°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 - 100 W
VE-B61-IU Vicor Corporation DC DC CONVERTER 12V 200W 유품4410 pcs 90% 1 - 16.67A 200V 12V - - - 3 kV VE-B61 Bulk Through Hole VE-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
VI-243-14 Vicor Corporation DC DC CONVERTER 84W 유품4740 pcs - - - - - - - - - - VI-243 Bulk - * - - - - - - - - -
CCK-2403SF TDK-Lambda Americas Inc DC DC CONVERTER 3.3V 1.32W 유품3630 pcs 70% 1 - 400mA 18V 3.3V - - - 500 V - Bulk Through Hole CCK (1.5W) -20°C ~ 70°C (With Derating) 1.10" L x 0.63" W x 0.31" H (27.9mm x 16.0mm x 7.9mm) 36V Isolated Module OCP ITE (Commercial) 6-DIP Module - 1.32 W
VE-JN2-CZ Vicor Corporation DC DC CONVERTER 15V 25W 유품134 pcs 90% 1 - 1.67A 36V 15V - - - 3 kV VE-JN2 Bulk Through Hole VE-J00™ (25W) -25°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 - 25 W
VI-BN4-EU Vicor Corporation DC DC CONVERTER 48V 200W 유품4740 pcs 88% 1 - 4.17A 36V 48V - - - 3 kV VI-BN4 Bulk Through Hole VI-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) 76V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 200 W
CCP-2405SF TDK-Lambda Americas Inc DC DC CONVERTER 5V 10W 유품4620 pcs 83% 1 - 2A 18V 5V - - - 500 V - Bulk Through Hole CCP (10W) -20°C ~ 70°C (With Derating) 1.79" L x 1.38" W x 0.33" H (45.5mm x 35.1mm x 8.4mm) 36V Isolated Module OCP ITE (Commercial) 8-DIP Module - 10 W
LAW005F ABB Power Electronics Inc. DC DC CONVERTER 3.3V 5W 유품5090 pcs 73% 1 - 1A 36V 3.3V - - - 1.5 kV - Bulk Through Hole LAW005 (5W) -25°C ~ 71°C 1.25' L x 0.80' W x 0.42' H (31.8mm x 20.3mm x 10.7mm) 75V Isolated Module OCP, OVP ITE (Commercial) Module - 5 W
VI-B0L-CX Vicor Corporation DC DC CONVERTER 28V 75W 유품98 pcs 90% 1 - 2.68A 10V 28V - - - 3 kV VI-B0L Bulk Through Hole VI-200™ (75W) -25°C ~ 85°C 4.60' L x 2.40' W x 0.50' H (116.8mm x 61.0mm x 12.7mm) 20V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 75 W
VE-J40-EX Vicor Corporation DC DC CONVERTER 5V 75W 유품4530 pcs 88% 1 - 15A 55V 5V - - - 3 kV VE-J40 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) 100V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 75 W
VE-J32-CX Vicor Corporation DC DC CONVERTER 15V 75W 유품144 pcs 90% 1 - 5A 42V 15V - - - 3 kV VE-J32 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) 60V Isolated Module OCP, SCP ITE (Commercial) Half Brick - 75 W
ZL9101MAIRZ Renesas Electronics America Inc DC DC CONVERTER 0.54-3.6V 43W 유품5250 pcs 95% 1 - 12A 4.5V 0.54 ~ 3.6V - - - - ZL9101 Tray Surface Mount ZL9101M -40°C ~ 85°C 0.59' L x 0.59' W x 0.14' H (15.0mm x 15.0mm x 3.5mm) 13.2V Non-Isolated PoL Module, Digital OCP, OTP, OVP, UVLO ITE (Commercial) 21-PowerBQFN Module 21-QFN (15x15) -
VE-JT0-EX Vicor Corporation DC DC CONVERTER 5V 75W 유품5150 pcs 88% 1 - 15A 66V 5V - - - 3 kV VE-JT0 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
MI-J53-IZ Vicor Corporation DC DC CONVERTER 24V 25W 유품3940 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-234-MV Vicor Corporation DC DC CONVERTER 48V 150W 유품4730 pcs 90% 1 - 3.13A 42V 48V - - - 3 kV VE-234 Bulk Through Hole VE-200™ (150W) -55°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 - 150 W
VI-BT3-CV Vicor Corporation DC DC CONVERTER 24V 150W 유품115 pcs 90% 1 - 2.08A 66V 24V - - - 3 kV VI-BT3 Bulk Through Hole VI-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-251-CU Vicor Corporation DC DC CONVERTER 12V 200W 유품70 pcs 90% 1 - 16.67A 100V 12V - - - 3 kV VE-251 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) 200V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 200 W
SW003A0A94Z ABB Power Electronics Inc. DC DC CONVERTER 5V 15W 유품5140 pcs 86% 1 Enable, Active High 3A 36V 5V - - - 2.25 kV - Tray Through Hole SW003 -40°C ~ 85°C 1.10' L x 0.96' W x 0.34' H (27.9mm x 24.4mm x 8.5mm) 75V Isolated Module Remote On/Off, OCP, OVP, UVLO ITE (Commercial) 6-DIP Module - 15 W
VE-2W0-MW Vicor Corporation DC DC CONVERTER 5V 100W 유품41 pcs 90% 1 - 20A 18V 5V - - - 3 kV VE-2W0 Bulk Through Hole VE-200™ (100W) -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 - 100 W
VE-252-MV Vicor Corporation DC DC CONVERTER 15V 150W 유품34 pcs 90% 1 - 10A 100V 15V - - - 3 kV VE-252 Bulk Through Hole VE-200™ (150W) -55°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 - 150 W
VE-2W0-EX Vicor Corporation DC DC CONVERTER 5V 75W 유품5330 pcs 88% 1 - 15A 18V 5V - - - 3 kV VE-2W0 Bulk Through Hole VE-200™ (75W) -10°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 - 75 W
CCK-0512DF TDK-Lambda Americas Inc DC DC CONVERTER +/-12V 1.44W 유품4740 pcs 68% 2 - 60mA, 60mA 4.5V 12V -12V - - 500 V - Bulk Through Hole CCK (1.5W) -20°C ~ 70°C (With Derating) 1.10" L x 0.63" W x 0.31" H (27.9mm x 16.0mm x 7.9mm) 9V Isolated Module OCP ITE (Commercial) 6-DIP Module - 1.44 W
VI-220-23 Vicor Corporation VI-220-23 36V/5V 30W SMD 유품4060 pcs - - - - - - - - - - VI-220 Bulk - * - - - - - - - - -
PCD3-12-1212 TDK-Lambda Americas Inc DC DC CONVERTER +/-12V 3W 유품5000 pcs - 2 - 125mA, 125mA 9V 12V -12V - - - - - Through Hole PC -20°C ~ 70°C (With Derating) 1.09" L x 0.78" W x 0.33" H (27.8mm x 19.8mm x 8.5mm) 18V Isolated Module OCP ITE (Commercial) 6-DIP Module - 3 W
VE-J42-EZ Vicor Corporation DC DC CONVERTER 15V 25W 유품140 pcs 88% 1 - 1.67A 55V 15V - - - 3 kV VE-J42 Bulk Through Hole VE-J00™ (25W) -10°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
VE-2N1-IU Vicor Corporation DC DC CONVERTER 12V 200W 유품4250 pcs 90% 1 - 16.67A 36V 12V - - - 3 kV VE-2N1 Bulk Through Hole VE-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) 76V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 200 W
VE-252-IW Vicor Corporation DC DC CONVERTER 15V 100W 유품4130 pcs 90% 1 - 6.67A 100V 15V - - - 3 kV VE-252 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) 200V Isolated Module OCP, OTP, OVP, SCP ITE (Commercial) Full Brick - 100 W
1...203204205206207208209...233
0 RFQ
쇼핑 카트 (0 Items)
비어 있습니다.
목록을 비교하십시오 (0 Items)
비어 있습니다.
피드백

귀하의 의견이 중요합니다!Allelco에서는 사용자 경험을 소중히 여기며 지속적으로 개선하기 위해 노력합니다.
피드백 양식을 통해 귀하의 의견을 공유하십시오. 즉시 응답하겠습니다.
Allelco을 선택해 주셔서 감사합니다.

주제
이메일
메모/주석
인증 코드
파일을 업로드하려면 드래그 또는 클릭하십시오
파일 업로드
유형 : .xls, .xlsx, .doc, .docx, .jpg, .png 및 .pdf.
최대 파일 크기 : 10MB