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Analog Devices Inc. LT3420EDD-1#PBF
- Part No.:
- LT3420EDD-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Management - Specialized
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3420EDD-1#PBF.pdf
- Description:
- IC PHOTOFLASH CAP CHARGER 10-DFN
- Quantity:
- Payment:
- Shipping:
Inventory:221
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Product details
Overview
LT3420EDD-1#PBF from Analog Devices (formerly Linear Technology) is a high-voltage photoflash capacitor charger IC using flyback topology. It delivers 1.0A peak switch current and 450mA controlled input current to charge a 100µF/320V capacitor from 5V in 3.5 seconds, targeting digital and film camera flash units requiring compact, efficient high-voltage generation.
For engineers reviewing the LT3420EDD-1#PBF datasheet, LT3420EDD-1#PBF pinout, LT3420EDD-1#PBF application, or LT3420EDD-1#PBF equivalent, key selection criteria include its 10-lead DFN (3mm × 3mm) package, 50V SW pin breakdown rating, adaptive off-time control for continuous-mode operation, and integrated refresh timer with user-programmable period via external capacitor.
Technical Context
The LT3420EDD-1#PBF implements an adaptive off-time control algorithm that maintains current-limited continuous conduction mode across the full charge cycle, eliminating high inrush currents. Its output voltage sensing monitors flyback voltage at the SW pin to regulate output without external resistor dividers or Zener diodes.
It features a dedicated refresh timer with programmable period (via CT pin capacitor), open-collector DONE output signaling charge completion, and CHARGE pin logic-level control (1.5V high threshold) enabling microprocessor interface. The internal NPN power switch has 50V DC breakdown rating and 130–230mV VCE(SAT) at 0.5A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | Up to 330V - supports standard photoflash capacitors without external feedback resistors. |
| Peak Switch Current | 1.0A (typ) - sets maximum energy transfer per cycle; enables compact transformer design. |
| Input Current Limit | 450mA (typ) - ensures stable operation from two AA cells or 1.8V–16V supplies. |
| SW Pin Breakdown Voltage | 50V - allows higher turns-ratio transformers than LT3420 (38V), improving efficiency at high output voltages. |
| Refresh Timer Thresholds | 0.5V (lower) / 1.0V (upper) - defines 2.5µA charge/discharge cycle for precise user-set refresh intervals. |
| Operating Temperature | –40°C to +85°C - qualified for consumer camera environments with thermal derating support. |
| Package | 10-Lead (3mm × 3mm) DFN with exposed pad - provides low thermal resistance (θJA = 43°C/W) for high-power pulse operation. |
Pinout & Package
LT3420EDD-1#PBF uses a 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for thermal and electrical performance. Pin numbering follows top-view layout with Pin 1 at bottom-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RREF (1) | Reference resistor connection | 2kΩ to GND sets internal 1V reference bias; determines feedback scaling accuracy. |
| VBAT (2) | Battery input supply | Accepts 1.8V–16V; powers transformer primary; requires local 4.7µF ceramic bypass. |
| RFB (3) | Feedback current input | Receives current proportional to VOUT/N; eliminates need for output voltage divider. |
| VCC (4) | IC supply rail | 2.5V–16V input; powers internal circuitry; requires ≥4.7µF X5R/X7R ceramic decoupling. |
| GND (5) | Power and signal ground | Common return for all analog/digital blocks; connects to exposed pad (Pin 11). |
| SW (6) | Internal NPN switch collector | Drives transformer primary; rated for 50V DC; minimize trace area to reduce EMI. |
| SEC (7) | Transformer secondary connection | Connects to secondary winding; polarity critical for proper flyback voltage sensing. |
| DONE (8) | Open-collector charge-complete flag | Pulled low during charging; high-Z when complete; requires external pull-up resistor. |
| CHARGE (9) | Enable/shutdown control | ≥1.5V initiates charging; ≤0.2V forces shutdown; edge-triggered for forced refresh entry. |
| CT (10) | Refresh timer capacitor node | 2.5µA current source charges/discharges external capacitor to set refresh interval. |
Key Features
| Feature | Design Value |
|---|---|
| Flyback topology with adaptive off-time control | Maintains continuous conduction mode across entire charge cycle, improving efficiency >75% and reducing transformer stress vs. discontinuous modes. |
| Indirect output voltage sensing | Monitors flyback pulse at SW pin to regulate VOUT; eliminates external resistor divider and Zener diode, saving board space and BOM cost. |
| User-programmable refresh timer | External capacitor on CT pin sets refresh interval; holds capacitor at target voltage with ~2mA average input current, extending standby time. |
| No external high-voltage components required | Integrated 50V-rated NPN switch and sensing architecture eliminate need for discrete HV transistors, Zeners, or op-amps in photoflash circuits. |
| Logic-compatible control interface | CHARGE and DONE pins operate at standard CMOS levels, enabling direct connection to microcontrollers without level-shifting. |
Applications
| Digital Camera Flash Unit | Film Camera Flash Unit |
|---|---|
Use Scenario: Rapid charging of 100µF photoflash capacitor to 320V within 3.5 seconds from dual-AA battery supply. IC Role / Device Role / Timing Role: High-voltage DC-DC converter with integrated switch, feedback, and charge-state signaling. Use Value: Enables compact, low-cost flash modules meeting consumer camera size and power constraints while supporting automatic refresh for ready-state operation. | Use Scenario: Charging 220µF/330V capacitor in mechanical film cameras with manual trigger timing. IC Role / Device Role / Timing Role: Standalone photoflash charger with DONE flag for mechanical shutter synchronization. Use Value: Eliminates discrete HV generator complexity; DONE signal directly interfaces with shutter release logic for precise flash timing. |
| High-Voltage Power Supplies | Portable Medical Imaging Devices |
Use Scenario: Generating 300–330V bias for CCD sensors or PMT detectors in battery-powered instruments. IC Role / Device Role / Timing Role: Efficient flyback controller optimized for capacitive loads and intermittent duty cycles. Use Value: Achieves >75% typical efficiency at 320V output, minimizing heat buildup and extending battery life in handheld diagnostic tools. | Use Scenario: Charging storage capacitors for pulsed X-ray or ultrasound probe drivers in portable imaging systems. IC Role / Device Role / Timing Role: Precision-controlled HV charger with programmable refresh to maintain readiness between imaging pulses. Use Value: CT pin programmability allows matching refresh rate to clinical workflow intervals, reducing standby power without compromising response time. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar photoflash capacitor charging applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3420EDD#PBF | Higher 1.4A peak switch current; 38V SW pin rating; charges 220µF to 320V in 3.7s; includes leakage spike blanking. | Better suited for larger capacitors and lower-output-voltage designs where 38V SW rating suffices. | Select LT3420EDD#PBF when charging >150µF or operating below 300V output; verify transformer turns ratio against 38V limit. |
| MAX1605EEE+ | Charge pump architecture; fixed 300V output; no transformer required; 28-pin QSOP package. | Limited to 300V; lower energy efficiency (~65%); no refresh mode; requires more external components. | Choose MAX1605EEE+ only for ultra-low-component-count, fixed-voltage designs where transformerless operation is mandatory. |
Compared with LT3420EDD#PBF, the LT3420EDD-1#PBF trades peak current for higher SW voltage rating (50V), enabling smaller transformers at 320V output; versus MAX1605EEE+, it delivers higher efficiency, programmable output, and autonomous refresh-critical for battery-operated flash systems.
Availability
LT3420EDD-1#PBF is available at Aetrix Electronics and suitable for digital camera flash units, film camera flash modules, and portable high-voltage power supplies requiring stable component supply and long-term production continuity.
Supply support for LT3420EDD-1#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices acquired Linear Technology in 2017 and maintains its precision analog and power management product lines with full technical documentation and long-term support.
The LT3420 family was designed specifically for photoflash capacitor charging in space-constrained, battery-powered imaging devices, emphasizing efficiency, integration, and ease of transformer interface.
FAQ
What is the maximum output voltage achievable with the LT3420EDD-1#PBF?
The LT3420EDD-1#PBF supports output voltages up to 330V, as verified in typical performance graphs (Figure G04/G05) and application circuits charging 100µF to 320V. Operation beyond 330V is not characterized and risks exceeding internal comparator thresholds or transformer insulation limits.
How does the LT3420EDD-1#PBF sense output voltage without a resistor divider?
The LT3420EDD-1#PBF senses output voltage indirectly by monitoring the flyback pulse amplitude at the SW pin during switch-off periods. This voltage is proportional to VOUT/N (turns ratio), allowing regulation without external resistors or Zener diodes-reducing component count and improving reliability.
Can the LT3420EDD-1#PBF be used with a 3.3V input supply?
Yes, the LT3420EDD-1#PBF operates from VBAT = 1.8V to 16V and VCC = 2.5V to 16V. At 3.3V input, it delivers regulated output (e.g., 320V) with typical efficiency of ~75% (Figure G13), and quiescent current remains below 130µA in non-switching mode per Electrical Characteristics table.
What is the purpose of the CT pin on the LT3420EDD-1#PBF?
The CT pin on the LT3420EDD-1#PBF connects to an external capacitor that sets the refresh timer period. A 2.5µA internal current source charges/discharges this capacitor between 0.5V and 1.0V thresholds, generating a user-defined interval (tREFRESH = CT / 2.5µF) to maintain capacitor charge with ~2mA average input current.
Is the LT3420EDD-1#PBF pin-compatible with the LT3420EDD#PBF?
No, the LT3420EDD-1#PBF is not pin-compatible with the LT3420EDD#PBF. While both use identical 10-lead DFN packages and share identical pin functions and numbering, their internal current limits, SW pin ratings (50V vs. 38V), and leakage blanking behavior differ-requiring separate transformer and layout validation per datasheet Figures F01/F02 and Table 1.
LT3420EDD-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Photoflash Capacitor Charger
- Current - Supply:
- 90µA
- Voltage - Supply:
- 2.2V ~ 16V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3420EDD-1#PBF FAQ
1.How can I place an order for LT3420EDD-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3420EDD-1#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LT3420EDD-1#PBF reliable?
The price and inventory of LT3420EDD-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3420EDD-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3420EDD-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3420EDD-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3420EDD-1#PBF?
LT3420EDD-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3420EDD-1#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LT3420EDD-1#PBF?
For technical support, including LT3420EDD-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3420EDD-1#PBF requirements.
6.How does Aetrix verify that LT3420EDD-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3420EDD-1#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LT3420EDD-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3420EDD-1#PBF?
All LT3420EDD-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3420EDD-1#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LT3420EDD-1#PBF part is unused and in its original packaging.
Return procedure for LT3420EDD-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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