LTC3545/LTC3545-1 - Triple 800mA Synchronous Step-Down Regulator - 2.25MHz


  • Three 800mA Outputs
  • High Efficiency: Up to 95%
  • 2.25V to 5.5V Input Voltage Range
  • Low Ripple (<20mVP-P) Burst Mode Operation
    IQ: 58uA
  • 2.25MHz Constant Frequency Operation
  • Synchronizable to External 1MHz to 3MHz Clock
  • Power Good Indicators Ease Supply Sequencing
  • 0.6V Reference Allows Low Output Voltages
  • Current Mode Operation/Excellent Transient Response
  • Low Profile 16-Lead 3mm × 3mm QFN Package

Typical Application

LTC3545 Typical Application
LTC3545 Typical Application


The LTC3545/LTC3545-1 are triple, high efficiency, monolithic synchronous buck regulators using a constant frequency, current mode architecture. The regulators operate independently with separate run pins. The 2.25V to 5.5V input voltage range makes the LTC3545/LTC3545-1 well suited for single Li-Ion battery-powered applications. Low ripple pulse skip mode or high efficiency Burst Mode operation is externally selectable. PWM pulse skip mode operation provides very low output ripple voltage while Burst Mode operation increases efficiency at low output loads.

Switching frequency is internally set to 2.25MHz, or the switching frequency can be synchronized to an external 1MHz to 3MHz clock. Power good indicators easily allow power on sequencing between the three regulators.

The internal synchronous switches increase efficiency and eliminate external Schottky diodes. Low output voltages are supported with the 0.6V feedback reference voltage.

The LTC3545-1 replaces the SYNC/MODE function with a third PGOOD pin and forces Burst Mode operation.


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
LTC3545EUD-1#PBF 3x3 QFN-16 UD E 05-08-1700 Yes
LTC3545EUD-1#TRPBF 3x3 QFN-16 UD E 05-08-1700 Yes
LTC3545EUD#PBF 3x3 QFN-16 UD E 05-08-1700 Yes
LTC3545EUD#TRPBF 3x3 QFN-16 UD E 05-08-1700 Yes
LTC3545IUD-1#PBF 3x3 QFN-16 UD I 05-08-1700 Yes
LTC3545IUD-1#TRPBF 3x3 QFN-16 UD I 05-08-1700 Yes
LTC3545IUD#PBF 3x3 QFN-16 UD I 05-08-1700 Yes
LTC3545IUD#TRPBF 3x3 QFN-16 UD I 05-08-1700 Yes

LTC3545 Package Drawing
LTC3545 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
LTC3545EUD-1#PBF 3x3 QFN-16 E $4.43 $3.10 Yes
LTC3545EUD-1#TRPBF 3x3 QFN-16 E $3.16 Yes
LTC3545EUD#PBF 3x3 QFN-16 E $4.43 $3.10 Yes
LTC3545EUD#TRPBF 3x3 QFN-16 E $3.16 Yes
LTC3545IUD-1#PBF 3x3 QFN-16 I $5.10 $3.57 Yes
LTC3545IUD-1#TRPBF 3x3 QFN-16 I $3.63 Yes
LTC3545IUD#PBF 3x3 QFN-16 I $5.10 $3.57 Yes
LTC3545IUD#TRPBF 3x3 QFN-16 I $3.63 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
DC1193A-A LTC3545EUD Demo Board | 2.25V to 5.5VIN, 1.2V@0.8A, 1.5V@0.8A, 1.8V@0.8A; SYNC Pin $150.00
DC1193A-B LTC3545EUD Demo Board | 2.25V to 5.5VIN, 1.2V@0.8A, 1.5V@0.8A, 1.8V@0.8A; PGOOD Pin, Burst Mode Only $150.00
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Click here to view our complete list of demo boards


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  • Portable Instruments
  • Point of Load Regulation

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