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Analog Devices Inc. LT3485EDD-3#PBF
- Part No.:
- LT3485EDD-3#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Management - Specialized
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3485EDD-3#PBF.pdf
- Description:
- IC CHARGER PHOTOFLASH 10-DFN
- Quantity:
- Payment:
- Shipping:
Inventory:221
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Product details
Overview
LT3485EDD-3#PBF from Analog Devices (formerly Linear Technology) is a photoflash capacitor charger IC with integrated high-voltage NPN power switch and IGBT gate driver. It operates from 2.5V to 10V input, delivers up to 2A peak switch current, charges photoflash capacitors to 320V using a 10.4:1 transformer, and features voltage output monitoring via VMONT pin. It is used in compact digital camera flash systems requiring fast charge time (2.5s for 100µF to 320V).
For engineers reviewing the LT3485EDD-3#PBF datasheet, LT3485EDD-3#PBF pinout, LT3485EDD-3#PBF application, or LT3485EDD-3#PBF equivalent, key selection considerations include its 2A switch current limit, 3mm × 3mm DFN-10 package, integrated IGBT drive with 270ns rise/180ns fall time, VOUT monitor accuracy of ±15mV at 30V SW–VBAT, and compatibility with small 5.8mm × 5.8mm × 3mm transformers.
Technical Context
The LT3485EDD-3#PBF implements a flyback topology with patented current-mode control, where output voltage is set by transformer turns ratio (N = VOUT/31.5 + 2) and detected via reflected SW–VBAT voltage. Its internal 2A current-limited NPN switch eliminates need for external Schottky diode and supports negative SW pin voltage tolerance.
It integrates dual functional blocks: a photoflash charging controller with DONE and CHARGE logic interface, and an independent IGBT gate driver powered by IGBTPWR. The VMONT pin provides real-time proportional voltage feedback (0–1V) during charging, synchronized to the flyback waveform, enabling microcontroller-based charge progress monitoring without external dividers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.6–1.8A typical; enables fast 2.5s charge of 100µF to 320V with minimal transformer size |
| VOUT Monitor Accuracy | ±15mV at SW–VBAT = 30V; ensures precise end-of-charge detection at 1V VMONT output |
| IGBT Output Rise/Fall Time | 270ns / 180ns into 4000pF; sufficient for reliable 4kV xenon lamp trigger pulse generation |
| Input Voltage Range (VIN) | 2.5V to 10V; supports single-cell Li-ion (3.6V) or dual AA (3V) battery operation |
| Operating Temperature | –40°C to 85°C; qualified for consumer portable electronics environments |
| Package | 10-lead 3mm × 3mm DFN with exposed pad; thermal resistance θJA = 43°C/W |
| Quiescent Current | 5–8mA (not switching); low standby draw extends battery life in flash standby mode |
Pinout & Package
LT3485EDD-3#PBF is housed in a 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CHARGE (1) | Enable control input | Active-high logic input; <0.3V = shutdown, >1V = initiate/continue charging cycle |
| VBAT (2) | Battery supply input | Provides power path for battery source; UVLO threshold at 1.7V; requires local 0.22µF ceramic bypass |
| VIN (3) | Main supply input | Primary power rail; UVLO threshold at 2.5V; requires local 4.7µF ceramic bypass |
| SW (4,5) | Switch collector node | Internal NPN collector; connects to transformer primary; withstands –1V to 50V; sets VOUT via turns ratio |
| IGBTOUT (6) | IGBT gate drive output | Push-pull driver output; pulls high to IGBTPWR, low to ~300mV; drives IGBT gate directly |
| IGBTIN (7) | IGBT logic enable input | CMOS-compatible input; >1.5V = IGBTON, <0.3V = IGBT OFF; zero quiescent current when low |
| IGBTPWR (8) | IGBT driver supply | Dedicated 0.1V-above-IGBT-Vth supply rail; powers IGBT driver independently of charging circuit |
| DONE (9) | Charge completion indicator | Open-collector NPN output; pulled low when target VOUT reached; requires external pull-up |
| VMONT (10) | Voltage monitor output | Analog output proportional to VOUT (0–1V range); valid only during active charging |
| Exposed Pad (11) | Thermal & electrical ground | Must be soldered to PCB ground plane; critical for thermal dissipation and noise reduction |
Key Features
| Feature | Design Value |
|---|---|
| No external voltage divider required | Output voltage detection uses internal SW–VBAT comparator (31.5V trip), eliminating resistor network and associated error sources |
| Integrated high-voltage NPN switch | Withstands –1V on SW pin; removes need for external Schottky diode and reduces BOM count and board area |
| Transformer size optimization | Patented control allows use of 5.8mm × 5.8mm × 3mm transformers, enabling ultra-thin camera module designs |
| Independent IGBT driver | Dedicated IGBTPWR rail and logic input allow flash triggering to operate concurrently with or independent of charging state |
| VOUT monitoring with microcontroller interface | VMONT pin outputs 0–1V analog signal linearly tracking capacitor voltage, enabling closed-loop charge control and diagnostics |
Applications
| Digital Camera Flash Charging | Smartphone Strobe Module |
|---|---|
Use Scenario: Rapid charging of 100µF photoflash capacitor to 320V in ≤2.5 seconds using dual AA batteries. IC Role / Device Role / Timing Role: Primary photoflash charger IC providing regulated high-voltage DC output and IGBT gate drive for xenon lamp ignition. Use Value: Enables sub-3-second flash recycle time in compact form factor while maintaining battery efficiency and thermal safety. | Use Scenario: Integration into slim smartphone bezel modules where height is constrained to ≤3mm. IC Role / Device Role / Timing Role: High-efficiency flyback controller with integrated IGBT driver, operating from single-cell Li-ion (3.6V). Use Value: Eliminates external Schottky diode and voltage divider, reducing component count and PCB area by >30% versus discrete solutions. |
| Portable Medical Imaging Flash | Industrial Inspection Flash System |
Use Scenario: Reliable flash charging in handheld dermatoscopes requiring stable 300–320V output across –10°C to 60°C ambient. IC Role / Device Role / Timing Role: Precision photoflash charger with temperature-stable VOUT comparator (±15mV accuracy) and robust UVLO protection. Use Value: Ensures consistent flash intensity across operating temperature range without recalibration or trimming. | Use Scenario: High-reliability flash unit for machine vision systems requiring >100,000 flash cycles with IGBT-triggered quenching. IC Role / Device Role / Timing Role: Dual-function IC delivering both capacitor charging and precise IGBT gate timing (270ns rise/180ns fall). Use Value: Enables controlled partial discharge (redeye reduction) and repeatable 4kV trigger pulses without secondary timing circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar photoflash charger applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3485EDD-0#PBF | 1.4A switch current limit; 3.7s charge time for 100µF/320V; higher VCESAT (210–300mV) | Better suited for lower-power, longer-life battery applications where peak current must be limited | Select LT3485EDD-0#PBF when system-level current draw or transformer thermal limits constrain peak switch current |
| LT3485EDD-2#PBF | 1A switch current limit; 5.5s charge time for 100µF/320V; intermediate efficiency and thermal profile | Optimized for balanced trade-off between charge speed and transformer size in mid-tier portable devices | Select LT3485EDD-2#PBF when design requires faster charge than LT3485EDD-0 but lower peak stress than LT3485EDD-3 |
Compared with LT3485EDD-0#PBF and LT3485EDD-2#PBF, the LT3485EDD-3#PBF delivers the shortest charge time (2.5s) and highest peak current (1.8A), making it optimal for premium digital cameras demanding fastest flash recycle-while LT3485EDD-0#PBF prioritizes battery longevity and LT3485EDD-2#PBF offers middle-ground thermal and timing performance.
Availability
LT3485EDD-3#PBF is available at Aetrix Electronics and suitable for digital camera flash charging, smartphone strobe modules, portable medical imaging flash, and industrial inspection flash systems requiring stable component supply, tight production scheduling, and long-term lifecycle support.
Supply support for LT3485EDD-3#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3485 family was designed by Linear Technology specifically for compact, battery-powered photoflash charging applications requiring integrated high-voltage switching, precise output voltage control, and direct IGBT gate drive-targeting space-constrained consumer imaging systems.
FAQ
What is the maximum output voltage achievable with LT3485EDD-3#PBF?
The LT3485EDD-3#PBF does not have a fixed maximum output voltage; it is set by transformer turns ratio using N = VOUT/31.5 + 2. With standard 10.4:1 transformers, it reliably achieves 320V output. Absolute maximum SW pin voltage is 50V, limiting practical VOUT to ≤350V depending on transformer isolation and layout. The LT3485EDD-3#PBF datasheet confirms operation up to 320V in all typical application circuits.
Does LT3485EDD-3#PBF require an external Schottky diode?
No, the LT3485EDD-3#PBF integrates a high-voltage NPN power switch that tolerates negative voltage on the SW pin, eliminating the need for an external Schottky diode. This is explicitly stated in the FEATURES section and verified in the ABSOLUTE MAXIMUM RATINGS (SW pin: –1V to 50V). The LT3485EDD-3#PBF's internal architecture handles reverse recovery inherently.
How does the VMONT pin function in LT3485EDD-3#PBF?
The VMONT pin on the LT3485EDD-3#PBF outputs a voltage proportional to the photoflash capacitor voltage during charging, ranging from 0V (≈64V actual) to 1V (exact end-of-charge point). It is derived from the flyback waveform and is only active while CHARGE and DONE are high. At 1V, the LT3485EDD-3#PBF terminates charging and pulls DONE low. This enables real-time microcontroller monitoring without external dividers.
What is the purpose of the IGBTPWR pin on LT3485EDD-3#PBF?
IGBTPWR is a dedicated supply pin for the integrated IGBT gate driver, electrically isolated from the main charging circuit. It must be ≥0.1V above the IGBT's turn-on threshold voltage and requires local ceramic bypassing. This separation allows the IGBT to be triggered independently-even during charging pauses-and minimizes interference between high-current switching and sensitive gate drive signals in the LT3485EDD-3#PBF.
Can LT3485EDD-3#PBF operate from a single 3.6V Li-ion cell?
Yes, the LT3485EDD-3#PBF supports VIN = 2.5V to 10V and VBAT = 1.7V to 10V, making it fully compatible with single-cell Li-ion (nominal 3.6V, range 2.8–4.2V). All typical application circuits in the datasheet use 3.6V input, and performance curves (e.g., charge time, efficiency) are characterized at VIN = VBAT = 3.6V. The LT3485EDD-3#PBF maintains regulation and IGBT drive functionality across this full battery discharge range.
LT3485EDD-3#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, Xenon
- Current - Supply:
- 5mA
- Voltage - Supply:
- 1.7V ~ 10V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3485EDD-3#PBF FAQ
1.How can I place an order for LT3485EDD-3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3485EDD-3#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 LT3485EDD-3#PBF reliable?
The price and inventory of LT3485EDD-3#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3485EDD-3#PBF is usually 5 days.
3.What payment methods are accepted for LT3485EDD-3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3485EDD-3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3485EDD-3#PBF?
LT3485EDD-3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3485EDD-3#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 LT3485EDD-3#PBF?
For technical support, including LT3485EDD-3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3485EDD-3#PBF requirements.
6.How does Aetrix verify that LT3485EDD-3#PBF is sourced from the original manufacturer or authorized distributors?
All LT3485EDD-3#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 LT3485EDD-3#PBF meets industry standards.
7.What is the process for return or replacement of LT3485EDD-3#PBF?
All LT3485EDD-3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3485EDD-3#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 LT3485EDD-3#PBF part is unused and in its original packaging.
Return procedure for LT3485EDD-3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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