Power Management Switching Regulator Xenon Photoflash Charger

LT3485 - Photoflash Capacitor Chargers with Output Voltage Monitor and Integrated IGBT Drive

Features

  • Integrated IGBT Driver
  • Voltage Output Monitor
  • Uses Small Transformers: 5.8mm × 5.8mm × 3mm
  • Operates from Two AA Batteries, Single Cell Li-Ion
    or Any Supply from 1.8V up to 10V
  • No Output Voltage Divider Needed
  • No External Schottky Diode Required
  • Charges Any Size Photoflash Capacitor
  • Available in 10-Lead (3mm × 3mm) DFN

Typical Application

LT3485 Typical Application
LT3485 Typical Application

Description

The LT3485 family of photoflash chargers are highly integrated ICs containing complete charger and IGBT drive functions. The patented control technique of the LT3485-x allows it to use extremely small transformers. Output voltage detection requires no external circuitry. The turns ratio of the transformer controls the final charge voltage. While charging, the output voltage on the capacitor may be monitored by a microcontroller from the monitor pin. Each device contains an on-chip high voltage NPN power switch, which can withstand negative voltages on the switch pin without an external Schottky diode. The device features a VBAT pin, which allows the use of two AA cells to charge the capacitor. The internal circuitry operates from the VIN pin. The LT3485-0 has a primary current limit of 1.4A, whereas the LT3485-3, LT3485-2, and LT3485-1 have current limits of 2A, 1A and 0.7A respectively. These different current limits result in tightly controlled input currents.

The CHARGE pin gives full control of the part to the user. Driving CHARGE low puts the part in shutdown. The DONE pin indicates when the part has completed charging. The LT3485 series of parts are housed in a leadless (3mm × 3mm) DFN package.

Packaging

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
Drawing		 RoHS
LT3485EDD-0#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3485EDD-0#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3485EDD-1#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3485EDD-1#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3485EDD-2#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3485EDD-2#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3485EDD-3#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3485EDD-3#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes


LT3485 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
(1-99)		 Price
(1k)*		 RoHS
LT3485EDD-0#PBF 3x3 DFN-10 E $3.21 $2.25 Yes
LT3485EDD-0#TRPBF 3x3 DFN-10 E $2.31 Yes
LT3485EDD-1#PBF 3x3 DFN-10 E $3.21 $2.25 Yes
LT3485EDD-1#TRPBF 3x3 DFN-10 E $2.31 Yes
LT3485EDD-2#PBF 3x3 DFN-10 E $3.21 $2.25 Yes
LT3485EDD-2#TRPBF 3x3 DFN-10 E $2.31 Yes
LT3485EDD-3#PBF 3x3 DFN-10 E $3.21 $2.25 Yes
LT3485EDD-3#TRPBF 3x3 DFN-10 E $2.31 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
DC895A-A LT3485EDD-0 | Photoflash Charger, 500mA Input Current, Vin=2.8V-4.2V, Vbat=1.8V-4.2V, 5V Max $100.00
DC895A-B LT3485EDD-1 | Photoflash Charger, 225mA Input Current, Vin=2.8V-4.2V, Vbat=1.8V-4.2V, 5V Max $100.00
DC895A-C LT3485EDD-2 | Photoflash Charger, 350mA Input Current, Vin=2.8V-4.2V, Vbat=1.8V-4.2V, 5V Max $100.00
Buy Now
Click here to view our complete list of demo boards

Applications

  • Digital Camera and Cell Phone Flash Charger

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LT3485-0
LT3485-1
LT3485-2
LT3485-3

Technical Support