LTC3619 - 400mA/800mA Synchronous Step-Down DC/DC with Average Input Current Limit


  • Programmable Average Input Current Limit: ±5% Accuracy
  • Dual Step-Down Outputs: Up to 96% Efficiency
  • Low Ripple (<25mVP-P) Burst Mode® Operation: IQ = 50μA
  • Input Voltage Range: 2.5V to 5.5V
  • Output Voltage Range: 0.6V to 5V
  • 2.25MHz Constant-Frequency Operation
  • Power Good Output Voltage Monitor for Each Channel
  • Low Dropout Operation: 100% Duty Cycle
  • Independent Internal Soft-Start for Each Channel
  • Current Mode Operation for Excellent Line and Load Transient Response
  • ±2% Output Voltage Accuracy
  • Short-Circuit Protected
  • Shutdown Current ≤ 1μA
  • Available in Small Thermally Enhanced 10-Lead MSE and 3mm × 3mm DFN Packages

Typical Application

LTC3619 Typical Application
LTC3619 Typical Application


The LTC3619 is a dual monolithic synchronous buck regulator using a constant frequency, current mode architecture.

The input supply voltage range is 2.5V to 5.5V, making it ideal for Li-Ion and USB powered applications. 100% duty cycle capability provides low dropout operation, extending the run time in battery-operated systems. Low output voltages are supported with the 0.6V feedback reference voltage. Channel 1 and channel 2 can supply 400mA and 800mA output current, respectively.

The LTC3619’s programmable average input current limit is ideal for USB applications and for point-of-load power supplies because the LTC3619’s limited input current will still allow its output to deliver high peak load currents without collapsing the input supply. When the sum of both channels’ currents exceeds the input current limit, channel 2 is current limited while channel 1 remains regulated. The operating frequency is internally set at 2.25MHz allowing the use of small surface mount inductors. Internal soft-start reduces in-rush current during start-up. The LTC3619 is available in small MSOP and 3mm × 3mm DFN packages and is also available in a low noise, high efficiency pulse skipping version, LTC3619B.

  Light Load Operation 
LTC3619 Low Ripple Burst Mode (< 20mVpp), Iq < 50uA
LTC3619B Pulse Skip (<5mVpp)


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
LTC3619EDD#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LTC3619EDD#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes
LTC3619EMSE#PBF MS-10E MSE E 05-08-1664 Yes
LTC3619EMSE#TRPBF MS-10E MSE E 05-08-1664 Yes
LTC3619IDD#PBF 3x3 DFN-10 DD I 05-08-1699 Yes
LTC3619IDD#TRPBF 3x3 DFN-10 DD I 05-08-1699 Yes
LTC3619IMSE#PBF MS-10E MSE I 05-08-1664 Yes
LTC3619IMSE#TRPBF MS-10E MSE I 05-08-1664 Yes

LTC3619 Package Drawing
LTC3619 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
LTC3619EDD#PBF 3x3 DFN-10 E $3.22 $2.25 Yes
LTC3619EDD#TRPBF 3x3 DFN-10 E $2.31 Yes
LTC3619EMSE#PBF MS-10E E $3.22 $2.25 Yes
LTC3619EMSE#TRPBF MS-10E E $2.31 Yes
LTC3619IDD#PBF 3x3 DFN-10 I $3.79 $2.65 Yes
LTC3619IDD#TRPBF 3x3 DFN-10 I $2.71 Yes
LTC3619IMSE#PBF MS-10E I $3.79 $2.65 Yes
LTC3619IMSE#TRPBF MS-10E I $2.71 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
DC1489A-A LTC3619EDD Demo Board | 5V input, VOUT1 = 3.3V @ 400mA, VOUT2 = 3.4V @ 500mA (2A Pulsed) $100.00
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  • High Peak Load Current Applications
  • USB Powered Devices
  • Supercapacitor Charging
  • Radio Transmitters and Other Handheld Devices

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