LT3420 - Photoflash Capacitor Chargers with Automatic Refresh
Features
- Charges 220µF to 320V in 3.7 Seconds from 5V (LT3420)
- Charges 100µF to 320V in 3.5 Seconds from 5V (LT3420-1)
- Charges Any Size Photoflash Capacitor
- Supports Operation from Two AA Cells or Any Supply from 1.8V to 16V
- Controlled Peak Switch Current: 1.4A (LT3420)
1.0A (LT3420-1) - Controlled Input Current: 840mA (LT3420)
450mA (LT3420-1) - Uses Standard Transformers
- Efficient Flyback Operation (>75% Typical)
- Adjustable Output
- Automatic Refresh
- Charge Complete Indicator
- No High Voltage Zener Diode Required
- No Output Voltage Divider Required
- Small 10-Lead MSOP Package
- Small 10-Lead (3mm × 3mm) DFN Package
Typical Application
Description
The LT3420/LT3420-1 charge high voltage photoflash capacitors quickly and efficiently. Designed for use in both digital and film cameras, these devices use a flyback topology to achieve efficiencies up to four times better than competing flash modules. A unique adaptive off-time control algorithm* maintains current-limited continuous mode transformer operation throughout the entire charge cycle, eliminating the high inrush current often found in modules.
The LT3420/LT3420-1 output voltage sensing scheme* monitors the flyback voltage to indirectly regulate the output voltage, eliminating an output resistor divider or discrete zener diode. This feature allows the capacitor to be held at a fully charged state without excessive power consumption. Automatic refresh (which can be defeated) allows the capacitor to remain charged while consuming an average input current of about 2mA, at a user-defined refresh rate. A logic high on the CHARGE pin initiates charging, while the DONE pin signals that the capacitor is fully charged.
The LT3420/LT3420-1 are available in 10-Lead MSOP and
(3mm × 3mm) DFN packages.
*Protected by U.S. Patents including 6518733.
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 |
|---|---|---|---|---|---|
| LT3420EDD-1#PBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3420EDD-1#TRPBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3420EDD#PBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3420EDD#TRPBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3420EMS-1#PBF | MS-10 | MS | E | 05-08-1661 | Yes |
| LT3420EMS-1#TRPBF | MS-10 | MS | E | 05-08-1661 | Yes |
| LT3420EMS#PBF | MS-10 | MS | E | 05-08-1661 | Yes |
| LT3420EMS#TRPBF | MS-10 | MS | E | 05-08-1661 | Yes |
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 | |
|---|---|---|---|---|---|---|
| LT3420EDD-1#PBF | 3x3 DFN-10 | E | $3.57 | $2.50 | Yes | |
| LT3420EDD-1#TRPBF | 3x3 DFN-10 | E | $2.60 | Yes | ||
| LT3420EDD#PBF | 3x3 DFN-10 | E | $3.57 | $2.50 | Yes | |
| LT3420EDD#TRPBF | 3x3 DFN-10 | E | $2.60 | Yes | ||
| LT3420EMS-1#PBF | MS-10 | E | $3.57 | $2.50 | Yes | |
| LT3420EMS-1#TRPBF | MS-10 | E | $2.56 | Yes | ||
| LT3420EMS#PBF | MS-10 | E | $3.57 | $2.50 | Yes | |
| LT3420EMS#TRPBF | MS-10 | E | $2.56 | Yes | ||
| Buy Now • Request Samples | ||||||
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 |
|---|---|---|---|
| DC460A | LT3420EMS | Strobe Capacitor Charger, High Voltage Supply, 1.8V to 10V Input, 320Vout | $150.00 | |
| DC646A | LT3420EMS | Strobe Capacitor Charger, High Voltage Supply, Input = 1.8V to 16V, Vout = 300V | $150.00 | |
| DC690A | LT3420EMS-1 | Strobe Capacitor Charger, High Voltage Supply, Vbatt = 1.8V - 6V, Vcc = 2.3V - 6V, Strobe Cap = 320V | $125.00 | |
| Buy Now | |||
Applications
- Digital Camera Flash Unit
- Film Camera Flash Unit
- High Voltage Power Supplies
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Design Tools
LTspice
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Models for the following parts are available in LTspice:
LT3420
LT3420-1
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
