LTC3899 - 60V Low IQ, Triple Output, Buck/Buck/Boost Synchronous Controller


  • Dual Buck Plus Single Boost Synchronous Controllers
  • Wide Bias Input Voltage Range: 4.5V to 60V
  • Outputs Remain in Regulation Through Cold Crank Down to a 2.2V Input Supply Voltage
  • Buck and Boost Output Voltages Up to 60V
  • Adjustable Gate Drive Level 5V to 10V (OPTI-DRIVE)
  • No External Bootstrap Diodes Required
  • Low Operating IQ: 29μA (One Channel On)
  • 100% Duty Cycle for Boost Synchronous MOSFET
  • Phase-Lockable Frequency (75kHz to 850kHz)
  • Programmable Fixed Frequency (50kHz to 900kHz)
  • Very Low Dropout Operation: 99% Duty Cycle (Bucks)
  • Low Shutdown IQ: 3.6μA
  • Fixed or Adjustable Boost Output Voltage Saves IQ
  • Small 38-Lead 5mm × 7mm QFN and TSSOP Packages

Typical Application

LTC3899 Typical Application
LTC3899 Typical Application


The LTC®3899 is a high performance triple output (buck/ buck/boost) DC/DC switching regulator controller that drives all N-channel synchronous power MOSFET stages. The constant frequency current mode architecture allows a phase-lockable frequency of up to 850kHz. The LTC3899 operates from a wide 4.5V to 60V input supply range. When biased from the output of the boost converter or another auxiliary supply, the LTC3899 can operate from an input supply as low as 2.2V after start-up.

The gate drive for the LTC3899 can be programmed from 5V to 10V to allow the use of logic-level or standard-level FETs and to maximize efficiency. Internal switches in the top gate drivers eliminate the need for external bootstrap diodes. The 29μA no-load quiescent current extends operating run time in battery-powered systems. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values.


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

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

Part Number Package Code Temp Package
LTC3899EFE#PBF TSSOP-38 FE E 05-08-1772 Yes
LTC3899EFE#TRPBF TSSOP-38 FE E 05-08-1772 Yes
LTC3899EUHF#PBF 5x7 QFN-38 UHF E 05-08-1701 Yes
LTC3899EUHF#TRPBF 5x7 QFN-38 UHF E 05-08-1701 Yes
LTC3899HFE#PBF TSSOP-38 FE H 05-08-1772 Yes
LTC3899HFE#TRPBF TSSOP-38 FE H 05-08-1772 Yes
LTC3899HUHF#PBF 5x7 QFN-38 UHF H 05-08-1701 Yes
LTC3899HUHF#TRPBF 5x7 QFN-38 UHF H 05-08-1701 Yes
LTC3899IFE#PBF TSSOP-38 FE I 05-08-1772 Yes
LTC3899IFE#TRPBF TSSOP-38 FE I 05-08-1772 Yes
LTC3899IUHF#PBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC3899IUHF#TRPBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC3899MPFE#PBF TSSOP-38 FE MP 05-08-1772 Yes
LTC3899MPFE#TRPBF TSSOP-38 FE MP 05-08-1772 Yes
LTC3899MPUHF#PBF 5x7 QFN-38 UHF MP 05-08-1701 Yes
LTC3899MPUHF#TRPBF 5x7 QFN-38 UHF MP 05-08-1701 Yes

LTC3899 Package Drawing
LTC3899 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
LTC3899EFE#PBF TSSOP-38 E $7.31 $5.12 Yes
LTC3899EFE#TRPBF TSSOP-38 E $5.18 Yes
LTC3899EUHF#PBF 5x7 QFN-38 E $7.07 $4.95 Yes
LTC3899EUHF#TRPBF 5x7 QFN-38 E $5.01 Yes
LTC3899HFE#PBF TSSOP-38 H $8.49 $5.94 Yes
LTC3899HFE#TRPBF TSSOP-38 H $6.00 Yes
LTC3899HUHF#PBF 5x7 QFN-38 H $8.23 $5.76 Yes
LTC3899HUHF#TRPBF 5x7 QFN-38 H $5.82 Yes
LTC3899IFE#PBF TSSOP-38 I $8.07 $5.65 Yes
LTC3899IFE#TRPBF TSSOP-38 I $5.71 Yes
LTC3899IUHF#PBF 5x7 QFN-38 I $7.82 $5.47 Yes
LTC3899IUHF#TRPBF 5x7 QFN-38 I $5.53 Yes
LTC3899MPFE#PBF TSSOP-38 MP $21.77 $15.24 Yes
LTC3899MPFE#TRPBF TSSOP-38 MP $15.30 Yes
LTC3899MPUHF#PBF 5x7 QFN-38 MP $21.09 $14.76 Yes
LTC3899MPUHF#TRPBF 5x7 QFN-38 MP $14.82 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
DC1898A LTC3899EFE Demo Board | Triple Buck/Buck/Boost Controller, Vout3 Powers VOUT1/VOUT2; 2.5V ≤ VIN ≤ 60V; VOUT1 = 5V @ 5A, VOUT2 = 8.5V @ 3A, Vout3 = 10V @ 5.5A $200.00
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  • Automotive Always-On and Start-Stop Systems
  • Distributed DC Power Systems
  • Multioutput Buck-Boost Applications

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Design Tools


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