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Analog Devices Inc. LT3751EFE#PBF
- Part No.:
- LT3751EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Management - Specialized
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3751EFE#PBF.pdf
- Description:
- IC CTRLR CAP CHRGR 20-TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,524
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Product details
Overview
LT3751EFE#PBF from Analog Devices (formerly Linear Technology) is a high-input-voltage flyback controller IC designed to rapidly charge large capacitors to user-adjustable high voltages (e.g., 500V in <1s), using transformer turns ratio and three external resistors for voltage setting, with optional low-noise regulated output via FB pin feedback. It integrates a rail-to-rail 2A MOSFET gate driver, features 106mV current sense threshold, and supports VCC input from 4.75V to 24V - used in professional photoflash, emergency strobes, and detonator systems.
For engineers reviewing the LT3751EFE#PBF datasheet, LT3751EFE#PBF pinout, LT3751EFE#PBF application, or LT3751EFE#PBF equivalent, key selection considerations include its dual-mode operation (capacitor charging vs. regulated HV supply), programmable over/undervoltage lockouts on VCC and VTRANS, integrated 20-pin TSSOP package with exposed GND pad, and precise 1.22V internal FB reference enabling stable regulation across –40°C to 125°C.
Technical Context
The LT3751EFE#PBF implements boundary-mode flyback control with start-up protection logic that uses an auxiliary current comparator and dual-threshold DCM detection (VTH1 = startup, VTH2 = normal mode) to prevent primary current runaway during low-output-voltage conditions. Its timing core includes a 26kHz one-shot clock and master latch architecture coordinating gate drive, fault latching, and DONE/FAULT signaling.
It supports both primary- and secondary-side output voltage sensing via RVOUT and FB pins, enables selectable 5.6V or 10.5V HVGATE clamp via CLAMP pin, and provides independent UVLO/OVLO monitoring on VCC and VTRANS using external resistor dividers tied to dedicated pins (UVLO1/2, OVLO1/2), each with 1.225V internal reference and ±50µA sensing current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.75V to 24V - enables direct compatibility with industrial 5V/12V/24V rails without external regulators. |
| Current Sense Threshold | 106mV (typ.) - sets precise peak switch current limit with minimal power loss in RSENSE. |
| FB Reference Voltage | 1.22V (±30mV) - defines regulation setpoint for low-noise HV output; hysteresis enables mode transition between charge and regulation. |
| Gate Drive Capability | 2A peak pull-up/pull-down - drives NMOS gates efficiently even under heavy capacitive load (CGATE = 3.3nF). |
| Operating Temperature | –40°C to 125°C junction - qualified for harsh environments including security strobes and detonator electronics. |
| UVLO/OVLO Threshold Accuracy | ±30mV at 1.225V reference - ensures reliable supply monitoring with predictable trip points using standard 1% resistors. |
| DCM Detection Threshold | Configurable via RDCM = 0.45 × RVTRANS - enables accurate discontinuous conduction mode initiation across wide VTRANS ranges (4.75V–65V). |
Pinout & Package
LT3751EFE#PBF is housed in a 20-lead plastic TSSOP package (4.4mm × 6.5mm) with exposed GND pad (Pin 21) requiring PCB soldering for thermal and electrical integrity. θJA = 38°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RVTRANS (Pin 1) | Transformer supply sense input | Connects to VTRANS via resistor; sets minimum operating voltage (≥4.75V) and enables VTRANS UVLO/OVLO. |
| UVLO1 (Pin 2) | VTRANS undervoltage lockout input | Triggers FAULT when VTRANS falls below 1.225V + 50µA×RUVLO1; disables switching until CHARGE toggled. |
| OVLO1 (Pin 3) | VTRANS overvoltage lockout input | Triggers FAULT when VTRANS exceeds 1.225V + 50µA×ROVLO1; requires CHARGE toggle to resume. |
| FAULT (Pin 6) | Open-collector fault indicator | Sinks current when VCC/VTRANS out-of-range or internal fault occurs; requires external pull-up. |
| DONE (Pin 7) | Open-collector charge-complete indicator | Sinks current when target output voltage reached; signals end of charge cycle or regulation stability. |
| CHARGE (Pin 8) | Charge initiation / enable control | Rising edge >1.5V starts new cycle; falling edge <0.3V forces shutdown; ramp rate must be 10ns–10ms. |
| CLAMP (Pin 9) | HVGATE clamp selection | Tie to GND for 10.5V clamp; tie to VCC for 5.6V clamp - selects gate drive voltage ceiling. |
| FB (Pin 10) | Feedback regulation input | Internal 1.22V reference; connects to resistive divider from output for low-noise regulation mode. |
| CSP/CSN (Pins 11–12) | Differential current sense inputs | Measure NMOS source voltage drop; set current limit as 106mV/RSENSE (charge mode) or down to 11mV/RSENSE (regulation). |
| VCC (Pin 13) | Main supply input | 4.75V–24V input; requires local X5R/X7R ceramic bypass capacitor; powers internal circuitry and gate driver. |
| LVGATE (Pin 14) | Low-voltage NMOS gate driver | Active only when VCC ≤ 8V; drives gate directly to VCC rail; tie to VCC when inactive. |
| HVGATE (Pin 15) | High-voltage NMOS gate driver | Drives NMOS gate to VCC – 2V per cycle; never connect external voltage/current source - risk of permanent damage. |
| RBG (Pin 16) | Bias generation reference | Sets bias current (0.98V/RBG) for RVOUT, RDCM, RVTRANS; determines output voltage scaling factor. |
| RVOUT (Pin 18) | Output voltage sense input | Develops current proportional to VOUT; used with RBG to calculate output voltage via transformer ratio and diode drop. |
| RDCM (Pin 20) | Discontinuous mode detection | Monitors VDRAIN decay; triggers next cycle when VDRAIN falls to VTRANS + 20µA×RDCM. |
| GND (Pin 21) | Power and signal ground | Exposed pad must be soldered to PCB ground plane for thermal dissipation and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Dual operational modes | Automatically transitions from rapid capacitor charging (FB < 1.16V) to low-noise regulated output (FB 1.16–1.34V) without external mode control. |
| Programmable supply monitoring | Four independent UVLO/OVLO inputs (UVLO1/2, OVLO1/2) with 1.225V reference and ±50µA sensing current enable robust VCC/VTRANS windowing. |
| Integrated 2A gate driver | Rail-to-rail operation down to 4.75V VCC; supports LVGATE/HVGATE dual-drive configuration for optimal efficiency across input voltage range. |
| Start-up protection logic | Uses auxiliary current comparator and dual-threshold DCM detection (VTH1/VTH2) to prevent primary current runaway during low-VOUT conditions. |
| Precision current limiting | 106mV differential sense threshold with ±6mV tolerance over temperature ensures repeatable peak current control in charge mode. |
| Flexible output sensing | Supports both primary-side (RVTRANS-based) and secondary-side (RVOUT+FB) voltage sensing - simplifies layout in isolated HV applications. |
Applications
| Professional Photoflash Systems | Emergency Strobe Lighting |
|---|---|
|
Use Scenario: Charging a 1000µF capacitor to 300–500V within 500ms for xenon tube flash discharge in studio lighting equipment. IC Role / Device Role / Timing Role: High-voltage flyback controller managing transformer energy transfer, current limiting, and charge completion signaling via DONE pin. Use Value: Enables sub-second charging with tight voltage accuracy (±1%) and built-in overvoltage protection prevents tube damage during repeated firing cycles. |
Use Scenario: Powering high-intensity LED or xenon strobes in fire alarm or aircraft evacuation systems requiring reliable 400V pulses at 1–10Hz. IC Role / Device Role / Timing Role: Regulated HV supply generator using FB feedback loop to maintain stable output despite battery voltage sag during emergency operation. Use Value: Maintains consistent light intensity across 10–24V input range; UVLO/OVLO lockouts ensure safe operation during brownout or surge events. |
| Security/Inventory Control Systems | Detonator Firing Circuits |
|
Use Scenario: Generating precisely timed 200–400V pulses to trigger electro-mechanical locks or RFID tag programming circuits in access control panels. IC Role / Device Role / Timing Role: Programmable capacitor charger with CHARGE pin triggering and DONE pin synchronization for deterministic pulse timing. Use Value: Eliminates need for external timing microcontroller; DONE signal enables downstream logic to initiate lock actuation or data write sequence. |
Use Scenario: Charging a low-inductance storage capacitor to 350–600V for initiating explosive bridgewire or exploding foil initiator (EFI) devices. IC Role / Device Role / Timing Role: Safety-critical HV charger with dual independent supply monitors (VCC/VTRANS), FAULT latching, and no-load stability guarantee. Use Value: Prevents inadvertent firing via hardware-enforced voltage windows; exposed GND pad ensures low-impedance discharge path for ESD-safe handling. |
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 |
|---|---|---|---|
| LTC3751EFE#PBF | Same die, identical pinout and specs; LTC prefix reflects Analog Devices' post-acquisition part numbering convention. | No functional difference; fully interchangeable in existing designs and BOMs. | Select when sourcing newer production lots or aligning with Analog Devices' current catalog nomenclature. |
| LT3751IFE#PBF | Identical functionality and pinout; differs only in temperature grade - rated for –40°C to 125°C (same as E-grade), but with tighter initial parametric testing. | Preferred for mission-critical applications requiring extended validation across full temp range, e.g., aerospace detonators. | Choose for enhanced long-term reliability assurance where qualification margin matters more than cost. |
Compared with LT3751EFE#PBF, LTC3751EFE#PBF offers identical performance with updated branding, while LT3751IFE#PBF adds tighter initial test limits for higher confidence in extreme-temperature deployment - neither requires PCB changes, but I-grade supports longer field life in safety-critical HV systems.
Availability
LT3751EFE#PBF is available at Aetrix Electronics and suitable for professional photoflash systems, emergency strobe lighting, and detonator firing circuits requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LT3751EFE#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and defense markets.
The LT3751EFE#PBF belongs to Linear's high-voltage power controller product line, engineered specifically for fast, reliable, and safe charging of large energy-storage capacitors in safety-critical and high-intensity lighting applications.
FAQ
What is the maximum VTRANS voltage supported by the LT3751EFE#PBF?
The LT3751EFE#PBF supports up to 65V on the RVTRANS pin, with an internal 60V clamp protecting the pin. Operation above 4.75V is required, and resistor dividers must ensure pin currents stay within ±1mA absolute maximum rating. This allows use with 48V or 60V intermediate bus architectures common in industrial strobe systems.
How does the LT3751EFE#PBF achieve low-noise regulated output?
The LT3751EFE#PBF achieves low-noise regulation by using the FB pin with a resistive divider from the output to ground, referencing its internal 1.22V bandgap. When FB voltage rises into the 1.16–1.34V window, the IC transitions from charge-only mode to regulation mode, applying peak-current and duty-cycle control to minimize ripple - confirmed in Typical Performance Characteristics Figure G14.
Can the LT3751EFE#PBF operate without an external NMOS switch?
No - the LT3751EFE#PBF is a controller only and requires an external NMOS power switch (e.g., SiHV series) connected to HVGATE/LVGATE. It does not integrate a power transistor. The CSP/CSN pins monitor source current through an external sense resistor, and gate drive timing is optimized for discrete MOSFETs with specified CGATE and Qg parameters.
What is the purpose of the CLAMP pin on the LT3751EFE#PBF?
The CLAMP pin on the LT3751EFE#PBF selects the internal clamp voltage applied to the HVGATE driver output: tying CLAMP to GND enables a 10.5V clamp, while tying it to VCC enables a 5.6V clamp. This protects the NMOS gate oxide during transient overvoltage events and matches gate drive requirements for different MOSFET VGS ratings - critical for reliability in detonator circuits.
Does the LT3751EFE#PBF require external compensation components for stability?
No external compensation is required for basic capacitor charging operation. However, when using FB-based regulation, a small RC network (e.g., 10kΩ + 100pF) may be added from FB to GND to improve phase margin - as recommended in Application Note AN137. The LT3751EFE#PBF's error amplifier is internally compensated for typical divider impedances up to 10MΩ.
LT3751EFE#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
LT3751EFE#PBF FAQ
1.How can I place an order for LT3751EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3751EFE#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 LT3751EFE#PBF reliable?
The price and inventory of LT3751EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3751EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3751EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3751EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3751EFE#PBF?
LT3751EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3751EFE#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 LT3751EFE#PBF?
For technical support, including LT3751EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3751EFE#PBF requirements.
6.How does Aetrix verify that LT3751EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3751EFE#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 LT3751EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3751EFE#PBF?
All LT3751EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3751EFE#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 LT3751EFE#PBF part is unused and in its original packaging.
Return procedure for LT3751EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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