LT8603 - 42V, Low IQ, Quad Output Triple Monolithic Buck Converter and Boost Controller


  • Flexible Power Supply System Capable of Four
  • Regulated Outputs with VBATT << VOUT
  • Two High Voltage Synchronous Buck Regulators
    • 3V to 42V Input Voltage Range
    • Output Currents Up to 2.5A and 1.5A
  • One Low Voltage Synchronous Buck Regulator
    • 2.6V to 5.5V Input Voltage Range
    • Output Currents Up to 1.8A
  • One Boost Controller Allows Buck Converters to Regulate with VBATT << VOUT
  • Selectable Burst Mode® Operation Allows Low 28μA IQ with High Voltage Channels Active
  • Programmable Power-On Reset
  • Individual Channel Power Good Indicators
  • Step-Down Switching Frequency: 250kHz to 2.2MHz
  • Available in 40-Lead QFN (6mm × 6mm) Package

Typical Application

LT8603 Typical Application
LT8603 Typical Application


The LT®8603 is a highly flexible, quad output regulator combining two high input voltage capable monolithic step-down switching regulators, one low input voltage capable monolithic step-down regulator, and a boost controller to satisfy a wide range of applications while occupying minimal board space.

With the boost controller configured to supply the chip VIN supply, the LT8603 produces three precisely regulated outputs even when the boost input voltage falls significantly below the regulated output voltages, such as during an automotive cold crank scenario. Alternatively, with the boost controller driven from one of the step-down regulator outputs or configured as a SEPIC, the LT8603 provides four precisely regulated outputs over a wide input voltage range.

The LT8603 provides robust regulation by including a cycle-by-cycle current limit for all step-down regulators, thermal shutdown, and a boost controller that can tolerate reverse battery connections and negative transient input voltages down to –42V.



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

Part Number Package Code Temp Package
LT8603EUJ#PBF 6x6 QFN-40 UJ E 05-08-1728 Yes
LT8603EUJ#TRPBF 6x6 QFN-40 UJ E 05-08-1728 Yes
LT8603IUJ#PBF 6x6 QFN-40 UJ I 05-08-1728 Yes
LT8603IUJ#TRPBF 6x6 QFN-40 UJ I 05-08-1728 Yes

LT8603 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
LT8603EUJ#PBF 6x6 QFN-40 E $7.64 $5.35 Yes
LT8603EUJ#TRPBF 6x6 QFN-40 E $7.70 $5.41 Yes
LT8603IUJ#PBF 6x6 QFN-40 I $8.42 $5.89 Yes
LT8603IUJ#TRPBF 6x6 QFN-40 I $8.48 $5.95 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
DC2114A LT8603 Demo Board | 42V, Quad Output Triple Monolithic Buck Converter and Boost Controller Contact Factory
DC2469A LT8603 Demo Board | 42V, Low IQ, Quad Output Triple Monolithic Buck Converter with Boost Channel as SEPIC Contact Factory
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Click here to view our complete list of demo boards


  • Automotive Stop-Start and Cold Crank Ride Through
  • Last-Gasp CPU Power Hold-Up
  • Industrial Controls and Power Supplies

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