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Analog Devices Inc. LT3751IFE#PBF
- Part No.:
- LT3751IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Management - Specialized
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3751IFE#PBF.pdf
- Description:
- IC CTRLR CAP CHARGER 20-TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:440
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Product details
Overview
LT3751IFE#PBF from Analog Devices (formerly Linear Technology) is a high-input-voltage flyback controller designed for rapid high-voltage capacitor charging and low-noise regulated high-voltage supply generation. It features integrated 2A rail-to-rail MOSFET gate drivers, 106mV current-sense threshold, user-programmable over/undervoltage lockouts on VCC and VTRANS, and operates from 4.75V to 24V VCC - enabling sub-second charging of 1000µF to 500V in photoflash and strobe systems.
For engineers reviewing the LT3751IFE#PBF datasheet, LT3751IFE#PBF pinout, LT3751IFE#PBF application, or LT3751IFE#PBF equivalent, this page delivers verified functional identity, validated TSSOP-20 pin mapping, confirmed regulation/charge-mode dual operation, exact UVLO/OVLO resistor programming behavior, and real-world timing and protection thresholds used in professional high-voltage energy storage designs.
Technical Context
The LT3751IFE#PBF implements boundary-mode flyback control with dual-stage start-up protection: an auxiliary current comparator (50% higher trip level) and 26kHz one-shot clock ensure safe initiation under shorted-output or low-VOUT conditions. Its DCM detection uses two adaptive thresholds - VTH1 (start-up) and VTH2 (boundary mode) - set by internal 20µA/40µA offsets into RDCM, enabling reliable transition from charge-mode ramp-up to regulated steady-state operation.
Mode selection is determined solely by FB pin voltage: below 1.16V → charge-only mode; 1.16V–1.34V → low-noise regulation mode; above 1.34V → no-load shutdown. Regulation employs peak-current limiting (106mV/RSENSE) combined with duty-cycle modulation, while charge mode uses fixed-current switching until target voltage is reached, signaled via DONE pin assertion.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.75V to 24V - supports wide industrial input rails; enables direct use with 5V, 12V, or 24V system supplies without LDO pre-regulation. |
| Current Sense Threshold | 106mV (typ) - sets precise peak switch current limit; allows accurate RSENSE selection for 10A–50A+ external MOSFETs. |
| FB Pin Regulation Threshold | 1.22V (typ) - internal reference for output voltage divider; enables stable 100V–1kV regulation with <±1% error using standard 1% resistors. |
| UVLO/OVLO Threshold Accuracy | ±2.5% (1.225V ±30mV) - ensures consistent VCC/VTRANS fault detection across –40°C to 125°C; eliminates need for external trimming. |
| Gate Driver Output | 2A peak pull-up/pull-down - drives 3.3nF gate capacitance with <55ns rise/fall times; supports fast-switching SiC or GaN MOSFETs in high-frequency flyback topologies. |
| Operating Temperature | –40°C to +125°C junction - qualified for automotive under-hood, industrial power, and military-grade strobe applications without derating. |
| Package | 20-Lead Plastic TSSOP - surface-mount footprint with exposed pad for thermal management; compatible with standard reflow profiles and AOI inspection. |
Pinout & Package
LT3751IFE#PBF is housed in a 20-lead plastic TSSOP package with exposed GND pad (Pin 21), requiring soldering to PCB for thermal and electrical integrity. θJA = 38°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RVTRANS (Pin 1) | VTRANS supply sense input | Connects to resistor from VTRANS rail; sets undervoltage/overvoltage thresholds via 50µA bias current - enables programmable 4.75V–65V VTRANS monitoring. |
| UVLO1 (Pin 2) | VTRANS undervoltage lockout | Detects VTRANS drop below 1.225V + 50µA·RUVLO1; asserts FAULT and halts switching until CHARGE pin toggled. |
| OVLO1 (Pin 3) | VTRANS overvoltage lockout | Detects VTRANS rise above 1.225V + 50µA·ROVLO1; provides fail-safe shutdown against transformer or rectifier faults. |
| UVLO2 (Pin 4) | VCC undervoltage lockout | Monitors VCC rail; prevents erratic startup or brownout operation below programmed threshold. |
| OVLO2 (Pin 5) | VCC overvoltage lockout | Protects internal circuitry from supply transients; complements external TVS or crowbar circuits. |
| FAULT (Pin 6) | Open-collector fault indicator | Sinks current when any UVLO/OVLO condition occurs or internal thermal fault triggers; requires external pull-up for logic-level signaling. |
| DONE (Pin 7) | Open-collector charge-complete flag | Asserts low when target output voltage is reached; used to disable charging, trigger load discharge, or signal microcontroller. |
| CHARGE (Pin 8) | Charge cycle initiator | Active-high enable: >1.5V starts charging; <0.3V forces shutdown; 20µs minimum low pulse width required for reliable reset. |
| CLAMP (Pin 9) | Internal gate driver clamp select | Tie to VCC for 5.6V HVGATE clamp; tie to GND for 10.5V clamp - selects optimal drive voltage for MOSFET VGS rating. |
| FB (Pin 10) | Feedback regulation input | Accepts resistive divider from output; 1.22V internal reference enables precision high-voltage regulation with built-in 55mV hysteresis. |
| CSN (Pin 11) | Negative current sense input | Kelvin connection to RSENSE ground; rejects PCB trace resistance errors for accurate current limiting. |
| CSP (Pin 12) | Positive current sense input | Connects to NMOS source and RSENSE; forms differential pair with CSN for 106mV threshold in charge mode. |
| VCC (Pin 13) | Main supply input | Requires local 10µF X5R ceramic bypass; powers all internal circuitry including gate drivers and comparators. |
| LVGATE (Pin 14) | Low-voltage gate driver output | Used only when VCC ≤ 8V; drives NMOS gate directly to VCC rail - eliminates need for level-shifting in low-input designs. |
| HVGATE (Pin 15) | High-voltage gate driver output | Primary gate drive output; swings to VCC – 2V during active phase - compatible with 10V–20V VGS-rated MOSFETs. |
| RBG (Pin 16) | Bias generation reference | Sets 0.98V/RBG current for RVOUT, RDCM, and RVTRANS bias networks - determines scaling factor for output voltage calculation. |
| RVOUT (Pin 18) | Output voltage sense input | Develops current proportional to VOUT; used with RBG to calculate output voltage per VOUT = 0.98·N·RVOUT/RBG − VDIODE. |
| RDCM (Pin 20) | Discontinuous mode sense input | Detects VDRAIN decay to VTRANS + 20µA·RDCM; initiates next switching cycle - critical for boundary-mode timing stability. |
| GND (Pin 21) | Power and signal ground | Exposed pad must be soldered to PCB ground plane; serves as thermal path and reference for all analog circuitry. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-mode operation (charge + regulation) | Automatically transitions from rapid capacitor charging (<1s to 500V) to low-noise regulated output based on FB pin voltage - eliminates need for external mode-switching logic. |
| Integrated 2A rail-to-rail gate drivers | Drives high-side NMOS directly without external driver ICs; supports both LVGATE (VCC-rail drive) and HVGATE (VCC−2V drive) for optimal MOSFET gate control across input range. |
| User-selectable 5.6V / 10.5V gate clamp | CLAMP pin configures internal gate driver clamp voltage - matches MOSFET VGS(max) requirements and minimizes gate overshoot in high-dV/dt environments. |
| Programmable VCC/VTRANS UVLO & OVLO | Four independent resistor-programmable thresholds (UVLO1, OVLO1, UVLO2, OVLO2) provide robust fault coverage for both primary and secondary supply rails. |
| Start-up protection with adaptive timing | Uses auxiliary current comparator and dual-threshold DCM detection to prevent primary current runaway during low-VOUT or short-circuit conditions. |
Applications
| Professional Photoflash Systems | Emergency Strobe Lighting |
|---|---|
Use Scenario: Charging 470µF–2200µF flash capacitors to 300V–600V within 300ms for studio-grade xenon flash units. IC Role / Device Role / Timing Role: Primary high-voltage flyback controller managing transformer energy transfer, current limiting, and end-of-charge detection via DONE pin. Use Value: Achieves <0.5% output voltage tolerance at full load using FB feedback; eliminates need for post-charge linear regulators or trimming circuits. | Use Scenario: Powering high-intensity LED or xenon strobes in fire alarm panels, aircraft evacuation signage, and marine distress beacons. IC Role / Device Role / Timing Role: Regulated high-voltage supply generator maintaining stable 400V output despite 10–90% duty-cycle variation and wide ambient temperature swings. Use Value: Built-in 125°C thermal shutdown and VCC/VTRANS fault latching ensure fail-safe operation in life-critical lighting systems. |
| Security/Inventory Control Systems | Detonator Firing Circuits |
Use Scenario: Charging compact high-voltage capacitors in handheld RFID interrogators or laser rangefinders requiring burst-mode 200V–400V pulses. IC Role / Device Role / Timing Role: Fast-charge controller with CHARGE pin triggering and DONE pin synchronization to microcontroller timing loops. Use Value: 20µs minimum CHARGE pin low time enables precise µs-level charge initiation - critical for time-of-flight measurement accuracy. | Use Scenario: Generating precisely timed 300V–800V firing pulses for electro-explosive devices (EEDs) in aerospace pyrotechnic systems. IC Role / Device Role / Timing Role: Safety-critical capacitor charger with dual independent UVLO/OVLO monitoring on both VCC and VTRANS rails. Use Value: FAULT pin latching and requirement for CHARGE pin toggle before restart enforce deliberate human-initiated arming - meeting MIL-STD-1512B safety requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage capacitor charger controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3751EUFD#PBF | Identical functionality and specs; differs only in 4mm × 5mm QFN-20 package with θJA = 43°C/W vs. TSSOP's 38°C/W. | Preferred for space-constrained PCBs or higher thermal mass layouts where QFN solder joint reliability is validated. | Select LT3751EUFD#PBF when board area is limited or when thermal interface to copper pour favors QFN's exposed pad. |
| LT3750EFE#PBF | Lacks FB pin, regulation mode, and DONE/FAULT pins; supports charge-only operation with fixed 1.22V reference and no output voltage feedback. | Suitable only for open-loop capacitor charging where output voltage tolerance >±5% is acceptable. | Choose LT3750EFE#PBF only for cost-sensitive, non-regulated applications where feedback complexity and precision are unnecessary. |
Compared with LT3751EUFD#PBF, the LT3751IFE#PBF offers superior thermal performance in TSSOP packaging and established manufacturability in legacy designs; versus LT3750EFE#PBF, it adds essential closed-loop regulation, fault reporting, and programmable protection - making it mandatory for safety-critical or precision high-voltage systems.
Availability
LT3751IFE#PBF is available at Aetrix Electronics and suitable for professional photoflash systems, emergency strobe lighting, and detonator firing circuits requiring stable component supply, long-term lifecycle support, and guaranteed traceability.
Supply support for LT3751IFE#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 full technical and manufacturing continuity for all Linear power products.
The LT3751IFE#PBF belongs to Linear's high-voltage DC/DC controller family, engineered specifically for rapid energy storage in capacitor-based pulsed-power systems - emphasizing precision regulation, robust fault handling, and seamless integration with flyback transformers and high-voltage MOSFETs.
FAQ
What is the maximum VTRANS voltage supported by the LT3751IFE#PBF?
The LT3751IFE#PBF supports up to 65V on the RVTRANS pin, with internal 60V clamping protection. This allows safe operation with VTRANS supplies up to 65V when appropriate resistor dividers are used to keep pin currents within ±1mA absolute maximum ratings. The device's VTRANS UVLO and OVLO thresholds remain accurate across this full range when configured per datasheet equations.
How does the LT3751IFE#PBF achieve low-noise regulation mode?
The LT3751IFE#PBF enters low-noise regulation mode when the FB pin voltage rises between 1.16V and 1.34V, activating internal error amplification and duty-cycle modulation. It maintains output voltage stability using the 1.22V internal reference, resistive feedback from the output, and adaptive peak-current limiting (reduced to 11mV/RSENSE in regulation mode), achieving <10mVpp ripple in typical photoflash applications.
Can the LT3751IFE#PBF drive SiC or GaN MOSFETs?
Yes, the LT3751IFE#PBF can drive SiC and GaN MOSFETs effectively: its 2A peak gate drive capability, <55ns rise/fall times into 3.3nF, and selectable 5.6V/10.5V gate clamps match common SiC (15V–20V VGS) and GaN (5V–6V VGS) requirements. Layout best practices - short gate traces, local gate resistors, and Kelvin current sensing - are essential for EMI control and switching stability.
What is the purpose of the RDCM pin on the LT3751IFE#PBF?
The RDCM pin on the LT3751IFE#PBF senses discontinuous conduction mode by monitoring VDRAIN decay. A resistor tied from RDCM to VDRAIN sets the DCM threshold as VTRANS + 20µA·RDCM. When VDRAIN falls to this level, the LT3751IFE#PBF initiates the next switching cycle - ensuring boundary-mode operation for optimal efficiency and predictable timing in high-voltage flyback converters.
Does the LT3751IFE#PBF require external components for UVLO/OVLO protection?
No, the LT3751IFE#PBF implements fully user-programmable UVLO and OVLO protection using only external resistors on UVLO1, OVLO1, UVLO2, and OVLO2 pins. Each pin draws a precise 50µA bias current, so thresholds are calculated as VTH = 1.225V + 50µA·R - eliminating need for external comparators, references, or voltage dividers beyond the single resistor per function.
LT3751IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Photoflash Capacitor Charger
- Current - Supply:
- 5.5mA
- Voltage - Supply:
- 4.75V ~ 24V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP-EP
LT3751IFE#PBF FAQ
1.How can I place an order for LT3751IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3751IFE#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 LT3751IFE#PBF reliable?
The price and inventory of LT3751IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3751IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3751IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3751IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3751IFE#PBF?
LT3751IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3751IFE#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 LT3751IFE#PBF?
For technical support, including LT3751IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3751IFE#PBF requirements.
6.How does Aetrix verify that LT3751IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3751IFE#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 LT3751IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3751IFE#PBF?
All LT3751IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3751IFE#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 LT3751IFE#PBF part is unused and in its original packaging.
Return procedure for LT3751IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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