LT3751 - High Voltage Capacitor Charger Controller with Regulation


  • Charges Any Size Capacitor
  • Low Noise Output in Voltage Regulation Mode
  • Stable Operation Under a No-Load Condition
  • Integrated 2A MOSFET Gate Driver with Rail-to-Rail Operation for VCC ≤ 8V
  • Selectable 5.6V or 10.5V Internal Gate Drive Voltage Clamp
  • User-Selectable Over/Undervoltage Detect
  • Easily Adjustable Output Voltage
  • Primary or Secondary Side Output Voltage Sense
  • Wide Input VCC Voltage Range (5V to 24V)
  • Available in 20-Pin QFN 4mm × 5mm and 20-Lead TSSOP Packages

Typical Application

LT3751 Typical Application
LT3751 Typical Application


The LT3751 is a high input voltage capable flyback controller designed to rapidly charge a large capacitor to a user-adjustable high target voltage set by the transformer turns ratio and three external resistors. Optionally, a feedback pin can be used to provide a low noise high voltage regulated output.

The LT3751 has an integrated rail-to-rail MOSFET gate driver that allows for efficient operation down to 4.75V. A low 106mV differential current sense threshold voltage accurately limits the peak switch current. Added protection is provided via user-selectable overvoltage and undervoltage lockouts for both VCC and VTRANS. A typical application can charge a 1000μF capacitor to 500V in less than one second.

The CHARGE pin is used to initiate a new charge cycle and provides ON/OFF control. The DONE pin indicates when the capacitor has reached its programmed value and the part has stopped charging. The FAULT pin indicates when the LT3751 has shut down due to either VCC or VTRANS voltage exceeding the user-programmed supply tolerances.


For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LT3751EFE#PBF TSSOP-20 FE E 05-08-1663 (CB) RoHS
LT3751EFE#TRPBF TSSOP-20 FE E 05-08-1663 (CB) RoHS
LT3751EUFD 4x5 QFN-20 UFD E 05-08-1711 RoHS
LT3751EUFD#PBF 4x5 QFN-20 UFD E 05-08-1711 RoHS
LT3751EUFD#TR 4x5 QFN-20 UFD E 05-08-1711 RoHS
LT3751EUFD#TRPBF 4x5 QFN-20 UFD E 05-08-1711 RoHS
LT3751IFE#PBF TSSOP-20 FE I 05-08-1663 (CB) RoHS
LT3751IFE#TRPBF TSSOP-20 FE I 05-08-1663 (CB) RoHS
LT3751IUFD 4x5 QFN-20 UFD I 05-08-1711 RoHS
LT3751IUFD#PBF 4x5 QFN-20 UFD I 05-08-1711 RoHS
LT3751IUFD#TR 4x5 QFN-20 UFD I 05-08-1711 RoHS
LT3751IUFD#TRPBF 4x5 QFN-20 UFD I 05-08-1711 RoHS

LT3751 Package Drawing
LT3751 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LT3751EFE#PBF TSSOP-20 E $5.46 $3.82 Yes
LT3751EFE#TRPBF TSSOP-20 E $3.88 Yes
LT3751EUFD 4x5 QFN-20 E $11.08 $7.30 No
LT3751EUFD#PBF 4x5 QFN-20 E $5.54 $3.65 Yes
LT3751EUFD#TR 4x5 QFN-20 E $7.42 No
LT3751EUFD#TRPBF 4x5 QFN-20 E $3.71 Yes
LT3751IFE#PBF TSSOP-20 I $6.06 $4.24 Yes
LT3751IFE#TRPBF TSSOP-20 I $4.30 Yes
LT3751IUFD 4x5 QFN-20 I $12.32 $8.12 No
LT3751IUFD#PBF 4x5 QFN-20 I $6.16 $4.06 Yes
LT3751IUFD#TR 4x5 QFN-20 I $8.24 No
LT3751IUFD#TRPBF 4x5 QFN-20 I $4.12 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1322A LT3751EUFD Demo Board | 8V VIN 40V; VOUT = 300V as a 400uF Capacitor Charger $125.00
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Click here to view our complete list of demo boards


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