Call us: +86 0755-82563503

Currency: $ US Dollar

Items : %s%s

Voltage Reference

Compare Image Name Manufacturer Pricing(USD) Quantity Weight(Kg) Size(LxWxH) Datasheet Factory Lead Time Lifecycle Status Mount Packaging Published Series Pbfree Code Part Status Moisture Sensitivity Level (MSL) Number of Terminations ECCN Code Max Operating Temperature Min Operating Temperature Length RoHS Status Lead Free Current Rating Radiation Hardening Number of Pins Additional Feature Package / Case REACH SVHC Reach Compliance Code Height Width Thickness Mounting Type Weight Operating Temperature Technology Operating Supply Current Current - Supply Height Seated (Max) HTS Code Number of Functions Nominal Supply Current Max Input Voltage JESD-609 Code Terminal Finish Terminal Position Terminal Form Peak Reflow Temperature (Cel) Supply Voltage Time@Peak Reflow Temperature-Max (s) Base Part Number Pin Count Output Type Temperature Grade Surface Mount Terminal Pitch JESD-30 Code Supply Voltage-Min (Vsup) Operating Temperature (Max) Operating Temperature (Min) Number of Channels Subcategory Qualification Status Power Supplies Supply Voltage-Max (Vsup) Output Voltage Number of Outputs Voltage - Output Voltage - Input Max Output Current Max Input Current Trim/Adjustable Output Analog IC - Other Type Output Voltage-Max Tolerance Temperature Coefficient Current - Output Min Input Voltage Supply Current-Max (Isup) Max Output Voltage Quiescent Current Accuracy Voltage Tolerance-Max Reference Voltage Min Output Voltage Topology Reference Type Output Voltage-Min Current - Cathode Voltage - Output (Min/Fixed) Temp Coef of Voltage-Max Noise - 0.1Hz to 10Hz Noise - 10Hz to 10kHz Voltage Reference
LM185BYH-1.2/NOPB LM185BYH-1.2/NOPB Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 6 Weeks ACTIVE (Last Updated: 6 days ago) Through Hole Bulk yes Active 1 (Unlimited) 2 EAR99 4.699mm ROHS3 Compliant Lead Free No 2 TO-46-2 Metal Can 2.667mm 4.699mm 2.362mm Through Hole -55°C~125°C TA BIPOLAR 1 BOTTOM WIRE LM185 Fixed Voltage References 1.235V 1 20mA NO TWO TERMINAL VOLTAGE REFERENCE ±1% 50ppm/°C 1.235V Shunt 10μA 150 ppm/°C 60μVrms
ADR292FRZ-REEL ADR292FRZ-REEL Analog Devices Inc. 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Surface Mount Tape & Reel (TR) XFET® yes Obsolete 1 (Unlimited) 8 EAR99 4.9mm ROHS3 Compliant Lead Free 8 8-SOIC (0.154, 3.90mm Width) unknown 3.9mm Surface Mount -40°C~125°C TA 18μA 1 18V e3 Matte Tin (Sn) DUAL GULL WING 260 5V 40 ADR292 8 Fixed 4.4V 1 Voltage References Not Qualified 4.1V 1 5V~15V 5mA NO THREE TERMINAL VOLTAGE REFERENCE ±0.1% 15ppm/°C 4.096V 15μA 4.096V Series 20 ppm/°C 12μVp-p
LT1004CS8-1.2#PBF LT1004CS8-1.2#PBF Analog Devices Inc. 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download PRODUCTION (Last Updated: 1 week ago) Surface Mount Bulk 70°C 0°C 5mm RoHS Compliant Lead Free No 8 SOIC No SVHC 1.498mm 3.988mm 8μA Adjustable 1 1.235V 20mA 0.3% 20 ppm/°C 20mA 1.235V 1.235V Fixed, Shunt 10μA 1.235V
TL431BQLPM TL431BQLPM Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 6 Weeks ACTIVE (Last Updated: 6 days ago) Tape & Box (TB) yes Active 1 (Unlimited) 3 EAR99 4.3mm ROHS3 Compliant Lead Free No 3 TO-226-3, TO-92-3 (TO-226AA) (Formed Leads) 5.34mm 4.3mm 3.6mm Through Hole 213.188414mg -40°C~125°C TA BIPOLAR 1 37V e3 Matte Tin (Sn) BOTTOM TL431 3 Adjustable NO 2.495V 1 Voltage References 36V 1 100mA YES THREE TERMINAL VOLTAGE REFERENCE ±0.5% 34 ppm/°C 36V Shunt 700μA 2.495V 92 ppm/°C
LM4040QAIM3X2.5/NOPB LM4040QAIM3X2.5/NOPB Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 6 Weeks ACTIVE (Last Updated: 6 days ago) Surface Mount Tape & Reel (TR) Automotive, AEC-Q100 yes Active 1 (Unlimited) 3 EAR99 2.92mm ROHS3 Compliant Lead Free 3 TO-236-3, SC-59, SOT-23-3 1.22mm 1.3mm 1mm Surface Mount -40°C~85°C TA BIPOLAR 1 e3 Matte Tin (Sn) DUAL GULL WING 260 NOT SPECIFIED LM4040 Fixed 0.95mm Voltage References Not Qualified 2.5V 1 15mA NO TWO TERMINAL VOLTAGE REFERENCE ±0.1% 100ppm/°C 2.5V 2.5V Shunt 65μA 100 ppm/°C 35μVrms
ZXRE4041FRSTOA ZXRE4041FRSTOA Diodes Incorporated 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Tape & Reel (TR) Obsolete 1 (Unlimited) E-Line-3 Through Hole -40°C~125°C TA ZXRE4041 Fixed ±3% 100ppm/°C 12mA Shunt 30μA 1.225V 60μVrms
REF192GS-REEL REF192GS-REEL Analog Devices Inc. 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Surface Mount Tape & Reel (TR) REF19 Obsolete 1 (Unlimited) 8 EAR99 4.9mm Non-RoHS Compliant 8 8-SOIC (0.154, 3.90mm Width) not_compliant 3.9mm Surface Mount -40°C~85°C TA CMOS 45μA 1 e0 DUAL GULL WING NOT APPLICABLE 3.3V NOT APPLICABLE REF192 8 Fixed 3V 1 Voltage References Not Qualified 2.5V 1 3V~15V NO THREE TERMINAL VOLTAGE REFERENCE ±0.4% 25ppm/°C 30mA 0.045mA 2.5V 15μA Series 25 ppm/°C 25μVp-p
REF5050IDGKR REF5050IDGKR Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 8 Weeks ACTIVE (Last Updated: 3 days ago) Tape & Reel (TR) yes Active 2 (1 Year) 8 EAR99 3mm ROHS3 Compliant Lead Free No 8 8-TSSOP, 8-MSOP (0.118, 3.00mm Width) 1.07mm 3mm 970μm Surface Mount 18.99418mg -40°C~125°C TA 1.2mA 1 800μA 18V e4 Nickel/Palladium/Gold (Ni/Pd/Au) DUAL GULL WING REF5050 8 Fixed YES 0.65mm 2.7V 1 5V 1 5.3V~18V 10mA YES THREE TERMINAL VOLTAGE REFERENCE ±0.05% 3ppm/°C 5.2V 5V 800μA 5V Series 3 ppm/°C 3μVp-p
REF194GP REF194GP Rochester Electronics 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Tube REF19 no Obsolete 3 (168 Hours) 8 9.27mm Non-RoHS Compliant 8-DIP (0.300, 7.62mm) 7.62mm Through Hole CMOS 5.33mm 1 e0 TIN LEAD DUAL 240 5V 30 8 INDUSTRIAL NO 2.54mm R-PDIP-T8 4.75V 85°C -40°C 15V 4.5V 1 NO THREE TERMINAL VOLTAGE REFERENCE 4.51V 4.49V 25 ppm/°C
LTC6652AHMS8-5#PBF LTC6652AHMS8-5#PBF Linear Technology / Analog Devices 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 8 Weeks PRODUCTION (Last Updated: 4 weeks ago) Surface Mount Tube 2007 Active 1 (Unlimited) 8 EAR99 3mm ROHS3 Compliant 8 8-TSSOP, 8-MSOP (0.118, 3.00mm Width) No SVHC 860μm 3mm Surface Mount -40°C~125°C TA CMOS 560μA 1 350μA 13.2V e3 Matte Tin (Sn) DUAL GULL WING 250 3V NOT SPECIFIED LTC6652 8 Fixed 0.65mm 1 Voltage References Not Qualified 5V 1 5.3V~13.2V 5mA NO THREE TERMINAL VOLTAGE REFERENCE ±0.05% 5ppm/°C 5V 350μA 5V Series 5 ppm/°C 2.8ppmp-p
FAN4040AIS35X FAN4040AIS35X ON Semiconductor 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 Tape and Reel 85°C -40°C RoHS Compliant 3 SOT-23-3 5V 100 ppm/°C Shunt
TLVH431NIDBZRVL TLVH431NIDBZRVL Nexperia 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Tape and Reel Active RoHS Compliant 3 Shunt Adjustable
LM4040D41IDCKR LM4040D41IDCKR Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 6 Weeks ACTIVE (Last Updated: 5 days ago) Tape & Reel (TR) yes Active 1 (Unlimited) 5 EAR99 2mm ROHS3 Compliant Lead Free No 5 5-TSSOP, SC-70-5, SOT-353 1.1mm 1.25mm 900μm Surface Mount -40°C~85°C TA BIPOLAR 1 e4 Nickel/Palladium/Gold (Ni/Pd/Au) DUAL GULL WING 260 5V LM4040 5 Fixed YES 1 Voltage References 4.096V 1 15mA NO TWO TERMINAL VOLTAGE REFERENCE ±1% 150ppm/°C 4.096V Shunt 88μA 80μVrms
LT6654BMPS6-3#TRPBF LT6654BMPS6-3#TRPBF Linear Technology / Analog Devices 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 16 Weeks Tape & Reel (TR) 2005 Active 1 (Unlimited) 6 EAR99 2.9mm ROHS3 Compliant SOT-23-6 Thin, TSOT-23-6 1.625mm Surface Mount -55°C~125°C TA BIPOLAR 600μA 1mm 8542.39.00.01 1 e3 Matte Tin (Sn) DUAL GULL WING 260 30 LT6654 6 Fixed YES 0.95mm R-PDSO-G6 3.5V Voltage References Not Qualified 36V 3V 1 3.5V~36V NO THREE TERMINAL VOLTAGE REFERENCE 3.0138V ±0.1% 20ppm/°C 10mA Series 3V 23 ppm/°C 1.6ppmp-p 2ppmrms
LM4050QAEM3-8.2/NOPB LM4050QAEM3-8.2/NOPB Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 6 Weeks ACTIVE (Last Updated: 1 day ago) Tape & Reel (TR) Automotive, AEC-Q100 yes Active 1 (Unlimited) 3 EAR99 2.92mm ROHS3 Compliant Lead Free 3 TO-236-3, SC-59, SOT-23-3 1.22mm 1.3mm 1mm Surface Mount -40°C~125°C TA BIPOLAR 1 e3 Matte Tin (Sn) DUAL GULL WING 260 NOT SPECIFIED LM4050 Fixed YES 0.95mm Voltage References Not Qualified 8.192V 1 NO TWO TERMINAL VOLTAGE REFERENCE ±0.1% 50ppm/°C 15mA Shunt 100μA 50 ppm/°C 150μVrms
LM336Z5X LM336Z5X ON Semiconductor 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 6 Weeks LIFETIME (Last Updated: 1 day ago) Through Hole Tape & Reel (TR) 2012 yes Last Time Buy 1 (Unlimited) 3 EAR99 5.2mm ROHS3 Compliant Lead Free 10mA No 3 TO-226-3, TO-92-3 (TO-226AA) (Formed Leads) No SVHC 5.33mm 4.19mm Through Hole 240mg 0°C~70°C TA BIPOLAR 1 e3 Tin (Sn) BOTTOM WIRE LM336 Fixed 1 Voltage References 5V 1 400mA YES TWO TERMINAL VOLTAGE REFERENCE ±4% 15mA 5V 1 % 6V 4V Shunt
LM4041D12IDBZTG4 LM4041D12IDBZTG4 Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 6 Weeks ACTIVE (Last Updated: 6 days ago) Tape & Reel (TR) yes Active 1 (Unlimited) 3 EAR99 2.92mm ROHS3 Compliant Lead Free No 3 OUTPUT VOLTAGE ADJUSTABLE FROM 1.225V TO 10V TO-236-3, SC-59, SOT-23-3 1.22mm 1.3mm 1mm Surface Mount -40°C~85°C TA BIPOLAR 1 e4 Nickel/Palladium/Gold (Ni/Pd/Au) DUAL GULL WING 260 LM4041 3 Fixed YES 0.95mm Voltage References 10V 1.225V 1 12mA NO TWO TERMINAL VOLTAGE REFERENCE ±1% 150ppm/°C 1.225V 1.225V Shunt 80μA 150 ppm/°C 20μVrms
AD780BR-REEL7 AD780BR-REEL7 Analog Devices Inc. 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Tape & Reel (TR) no Obsolete 1 (Unlimited) 8 EAR99 4.9mm Non-RoHS Compliant Contains Lead No 8 USER CONFIGURABLE 2.5 V/3.0 V REFERENCE VOLTAGE 8-SOIC (0.154, 3.90mm Width) 3.9mm Surface Mount -40°C~85°C TA BIPOLAR 1mA 1 1mA 36V e0 DUAL GULL WING 240 5V 30 AD780 8 Programmable YES 4V 1 Voltage References 3V 1 4V~36V 10mA YES THREE TERMINAL VOLTAGE REFERENCE ±0.04% ±0.03% 3ppm/°C 1mA 3V Series, Shunt ±2.5V ±3V 3 ppm/°C 4μVp-p
REF198GS REF198GS Analog Devices Inc. 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Tube REF19 no Obsolete 1 (Unlimited) 8 EAR99 4.9mm Non-RoHS Compliant Contains Lead No 8 8-SOIC (0.154, 3.90mm Width) 3.9mm Surface Mount -40°C~85°C TA CMOS 45μA 1 45μA 18V e0 DUAL GULL WING 235 5V 20 REF198 8 Fixed YES 4.5V 1 Voltage References 4.096V 1 4.5V~15V 30mA NO THREE TERMINAL VOLTAGE REFERENCE ±0.24% 25ppm/°C 0.045mA 4.096V 45μA 4.096V Series 25 ppm/°C 40μVp-p
ADR1500BKSZ-REEL ADR1500BKSZ-REEL Analog Devices Inc. 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 8 Weeks PRODUCTION (Last Updated: 2 weeks ago) Tape & Reel (TR) no Active 1 (Unlimited) 3 EAR99 2mm ROHS3 Compliant Contains Lead No 3 SC-70, SOT-323 1.25mm Surface Mount -40°C~85°C TA BIPOLAR 1.1mm 1 e4 Nickel/Palladium/Gold (Ni/Pd/Au) DUAL GULL WING 260 ADR1500 3 Fixed YES 0.65mm Voltage References 1.2875V 1 10mA 10mA NO TWO TERMINAL VOLTAGE REFERENCE ±0.2% 220ppm/°C 1.2875V 1.2875V Shunt 50μA 220 ppm/°C 5μVp-p 20μVrms
LM4050BEM3X-5.0/NOPB LM4050BEM3X-5.0/NOPB Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 6 Weeks ACTIVE (Last Updated: 5 days ago) Surface Mount Tape & Reel (TR) yes Active 1 (Unlimited) 3 EAR99 2.92mm ROHS3 Compliant Lead Free No 3 TO-236-3, SC-59, SOT-23-3 1.22mm 1.3mm 1mm Surface Mount -40°C~125°C TA BIPOLAR 1 e3 Matte Tin (Sn) DUAL GULL WING 260 LM4050 3 Fixed 0.95mm 1 Voltage References 5V 1 15mA NO TWO TERMINAL VOLTAGE REFERENCE ±0.2% 50ppm/°C 5V Shunt 90μA 50 ppm/°C 93μVrms
VRE305KS VRE305KS Apex Microtechnology 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Surface Mount Tube 2009 Obsolete 1 (Unlimited) RoHS Compliant 8-SMD, Flat Lead Surface Mount -40°C~85°C TA 7mA VRE305 Fixed 13.5V~22V ±0.02% 1ppm/°C 10mA 5V Series 3μVp-p
ZR285R02STOB ZR285R02STOB Diodes Incorporated 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Through Hole Tape & Reel (TR) Obsolete 1 (Unlimited) RoHS Compliant Lead Free 3 TO-226-3, TO-92-3 (TO-226AA) (Formed Leads) unknown Through Hole -40°C~85°C TA ZR285 Fixed 1 2.5V ±2% 90ppm/°C 20mA 2.5V Shunt 20μA 60μVrms
TLE2425CPS TLE2425CPS Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 6 Weeks ACTIVE (Last Updated: 5 days ago) Surface Mount Tube yes Active 1 (Unlimited) 8 6.2mm ROHS3 Compliant Lead Free 8 8-SOIC (0.209, 5.30mm Width) 2mm 5.3mm 1.95mm Surface Mount 122.611688mg 0°C~70°C TA 1 40V e4 Nickel/Palladium/Gold (Ni/Pd/Au) DUAL GULL WING 260 5V NOT SPECIFIED TLE2425 8 Fixed 4V 1 Power Management Circuits Not Qualified 5V 2.5V 1 4V~40V 20mA NO THREE TERMINAL VOLTAGE REFERENCE ±0.8% 20ppm/°C Typical Ground Reference (Virtual) 100μVrms
LT6656BCDC-5#PBF LT6656BCDC-5#PBF Analog Devices, Inc. 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 Non-RoHS Compliant 6 DFN
LT1461CIS8-3#TRPBF LT1461CIS8-3#TRPBF Linear Technology / Analog Devices 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download 8 Weeks PRODUCTION (Last Updated: 1 month ago) Surface Mount Tape & Reel (TR) 2002 Active 1 (Unlimited) 8 EAR99 4.9mm ROHS3 Compliant Lead Free 8 8-SOIC (0.154, 3.90mm Width) 3.9mm Surface Mount -40°C~85°C TA BIPOLAR 70μA 1.75mm 1 e3 Matte Tin (Sn) DUAL GULL WING 260 5.5V 30 LT1461 8 Fixed 1.27mm 3.5V Voltage References Not Qualified 20V 3V 1 3.5V~20V NO THREE TERMINAL VOLTAGE REFERENCE ±0.08% 12ppm/°C 100mA 3V 50μA 3V Series 12 ppm/°C 8ppmp-p 9.6ppmrms
ZRC500Y02 ZRC500Y02 Zetex 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 download Bulk 1 (Unlimited) 2 EAR99 85°C -40°C 4.77mm Non-RoHS Compliant not_compliant 4.01mm 2.41mm BIPOLAR 8542.39.00.01 1 e3 Matte Tin (Sn) SINGLE THROUGH-HOLE 260 40 INDUSTRIAL NO 2.54mm R-PSIP-T2 Voltage References Not Qualified 5V 1 5V NO TWO TERMINAL VOLTAGE REFERENCE 90 ppm/°C 5mA 2% Shunt
LT1460ACS8-2.5 LT1460ACS8-2.5 Analog Devices, Inc. 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 Surface Mount 1 (Unlimited) 8 EAR99 70°C 0°C 5mm RoHS Compliant Contains Lead 8 SOIC 1.48mm 3.99mm BIPOLAR 165μA 1 30V e0 Tin/Lead (Sn/Pb) DUAL GULL WING 255 5V 40 Fixed COMMERCIAL 1.27mm 3.4V Not Qualified 20V 2.5V 1 2.5V NO THREE TERMINAL VOLTAGE REFERENCE 0.075% 10 ppm/°C 40mA 2.5V 130μA 2.5V Fixed, Series
LT1009IPWE4 LT1009IPWE4 Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 Surface Mount Tube Obsolete 1 (Unlimited) 8 EAR99 4.4mm ROHS3 Compliant Lead Free 8 +/-5 PERCENT ADJUSTABLE REFERENCE VOLTAGE 8-TSSOP (0.173, 4.40mm Width) 3mm Surface Mount 39.008944mg -40°C~85°C TA BIPOLAR 1 DUAL GULL WING NOT SPECIFIED NOT SPECIFIED LT1009 8 Fixed 0.65mm 1 Voltage References Not Qualified 2.5V 1 YES TWO TERMINAL VOLTAGE REFERENCE ±0.4% 35ppm/°C 10mA Shunt 400μA 35 ppm/°C
LM4050QBEM3-5.0/NOPB LM4050QBEM3-5.0/NOPB Texas Instruments 0.0000
RFQ

Min: 1

Mult: 1

0.00000000 6 Weeks ACTIVE (Last Updated: 1 week ago) Tape & Reel (TR) Automotive, AEC-Q100 yes Active 1 (Unlimited) 3 EAR99 2.92mm ROHS3 Compliant Lead Free 3 TO-236-3, SC-59, SOT-23-3 1.22mm 1.3mm 1mm Surface Mount -40°C~125°C TA BIPOLAR 1 e3 Matte Tin (Sn) DUAL GULL WING 260 NOT SPECIFIED LM4050 Fixed YES 0.95mm Voltage References Not Qualified 5V 1 NO TWO TERMINAL VOLTAGE REFERENCE ±0.5% 50ppm/°C 15mA Shunt 90μA 50 ppm/°C 93μVrms
Settings Need Help?
Top FAQ's

How can I quickly find answers to my questions?

Please visit the Help & Support area of our website to find information regarding ordering, shipping, delivery and more.

What is my Order Status?

Registered users can track orders from their account dropdown, or click here. *Order Status may take 12 hours to update after initial order is placed.

How do I return product?

Users can begin the returns process by starting with our Returns Page.

How do I find price and availability?

Quotes can be created by registered users in myLists.

How do I create a 'HK JDW' Account?

Visit the Registration Page and enter the required information. You will receive an email confirmation when your registration is complete.

United Kingdom/GBP Summary
Fast Shipping Fast Delivery

Orders are typically delivered to United Kingdom within 48 hours depending on location.

Free Shipping Free Shipping

Free delivery to United Kingdom on orders of £33 or more. A delivery charge of £12 will be billed on all orders less than £33.

Incoterms Incoterms

DDP (Duty and customs paid by HK JDW)

Payment Options Payment Types

Credit account for qualified institutions and businesses

Payment in Advance by Wire Transfer

Visa Mastercard American Express PayPal Apple Pay Google Pay

Marketplace Marketplace Product

More Products From Fully Authorized Partners

Average Time to Ship 1-3 Days, extra ship charges may apply. Please see product page, cart, and checkout for actual ship speed.

Incoterms: CPT (Duty, customs, and applicable VAT/Tax due at time of delivery)

For more information visit Help & Support