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Analog Devices Inc. LT3840EFE#PBF
- Part No.:
- LT3840EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3840EFE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:974
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Product details
Overview
LT3840EFE#PBF from Analog Devices is a high-voltage synchronous step-down switching regulator controller supporting 2.5V to 60V input, delivering up to 60V output with ±1.25% FB reference accuracy, 75µA quiescent current in Burst Mode, and programmable 50kHz–1MHz switching frequency. It integrates a 7.5V auxiliary buck-boost bias supply for gate drive and internal circuitry, enabling efficient operation across wide VIN ranges in automotive and industrial power systems.
For engineers reviewing the LT3840EFE#PBF datasheet, LT3840EFE#PBF pinout, LT3840EFE#PBF application, or LT3840EFE#PBF equivalent, key selection considerations include its accurate average current limit (±5% over temperature), dual-mode soft-start/tracking via TK/SS, integrated INTVCC regulation, and support for high-side N-channel MOSFETs with 75ns non-overlap timing - all critical for stable high-current DC/DC designs.
Technical Context
The LT3840EFE#PBF employs a constant-frequency, peak current mode architecture with independent voltage and average current control loops. Its internal 7.5V auxiliary buck-boost regulator powers gate drivers and IC bias, eliminating external bias supplies while maintaining efficiency from 2.5V to 60V input.
It supports three light-load operating modes (Burst, pulse-skipping, continuous) selected via MODE pin, and features precision OVLO/UVLO thresholds (±1.25% typical), 90% PG threshold hysteresis, and reverse-current protection that disables BG before inductor current reversal - ensuring robust operation in transient-heavy environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 60V - enables single-supply operation across automotive battery (cold crank to load dump) and industrial 48V DC distribution systems. |
| Output Voltage Range | Up to 60V - supports high-side buck configurations for intermediate bus generation without external level-shifting. |
| FB Reference Voltage | 1.250V ±1.25% (E-grade) - ensures tight output regulation stability over –40°C to 125°C junction temperature. |
| Quiescent Current | 75µA at 12VIN → 3.3VOUT in Burst Mode - extends battery runtime in always-on telemetry and sensor nodes. |
| Switching Frequency | 50kHz to 1MHz (RT-programmable) - balances MOSFET switching loss vs. magnetics size for optimized thermal and footprint performance. |
| Auxiliary Bias Output | 7.5V ±3.3% regulated INTVCC - powers large N-channel MOSFET gates and internal circuitry without dropout or thermal derating at low VIN. |
| Average Current Limit Accuracy | ±5% over temperature - enables precise current-source operation for LED drivers or battery charging with minimal calibration. |
Pinout & Package
LT3840EFE#PBF is housed in a 28-lead plastic TSSOP package (FE) with exposed pad (Pin 29) soldered to PCB ground for thermal and electrical integrity. θJA = 30°C/W, θJC = 10°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 14) | Main input supply rail | Decoupled with 0.1µF ceramic capacitor; powers internal reference and enables auxiliary bias startup above 2.5V. |
| EN (Pin 13) | Enable control with shutdown mode | 1.25V threshold with 2mV hysteresis; pulls internal circuitry into 0.1µA shutdown when below 0.3V. |
| FB (Pin 7) | Feedback input for output voltage regulation | Compares against 1.25V reference; also serves as input for PG and OVP comparators. |
| TK/SS (Pin 6) | Soft-start and output voltage tracking input | Internal 9µA current source charges external CSS; allows ramp control or external supply tracking during sequencing. |
| ICTRL (Pin 17) | Average current limit programming | Voltage input (0–1V) sets max average output current; floating defaults to 50mV sense threshold (1A per 50mV across RSENSE). |
| IMON (Pin 16) | Average output current monitor | 20× amplified and filtered SENSE differential voltage - provides analog telemetry for system diagnostics. |
| TG / BG (Pins 22 / 25) | High-current N-MOSFET gate drivers | 7.5V drive with 75ns non-overlap; supports parallel MOSFETs for >20A applications. |
| SENSE+ / SENSE– (Pins 19 / 20) | Differential current sense inputs | Accept common-mode voltage up to 60V; enable accurate high-side current sensing without shunt relocation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated auxiliary buck-boost regulator | Generates stable 7.5V INTVCC from 2.5V–60V VIN - eliminates external bias supply and enables full-range gate drive efficiency. |
| Programmable average current limit | Set via ICTRL voltage (0–1V) with ±5% accuracy over temperature - supports regulated current-source topologies without external op-amps. |
| Three selectable light-load modes | Burst Mode (75µA IQ), pulse-skipping, or continuous conduction - optimizes efficiency across 100µA–20A load range. |
| Reverse-current protection | Disables BG before inductor current reaches zero - prevents negative current flow and maintains DCM operation in Burst Mode. |
| Accurate input OVLO/UVLO | 1.25V threshold with ±1.25% tolerance and programmable hysteresis - protects against transients up to 80V while supporting wide-input brown-in/brown-out windows. |
Applications
| Automotive Infotainment Power | Industrial 48V DC-DC Converter |
|---|---|
|
Use Scenario: Powering FPGA, DSP, and display controllers in head units with cold-crank (4.5V) to load-dump (40V) battery transients. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating 5V/3.3V rails with integrated 7.5V gate drive and input OVLO/UVLO monitoring. Use Value: Eliminates need for external bias LDO and discrete protection ICs, reducing BOM count by ≥3 components while maintaining <1% output deviation during 100ms 36V transients. |
Use Scenario: Converting 48V intermediate bus to 12V/5V for PLC I/O modules and motor drives in factory automation. IC Role / Device Role / Timing Role: High-efficiency step-down controller driving paralleled 5mΩ MOSFETs with 500kHz switching and synchronized clock input. Use Value: Delivers >94% efficiency at 15A load with 75µA quiescent current in standby - enabling fanless enclosure design and meeting IEC 61000-4-5 surge immunity requirements. |
| LED Driver for Street Lighting | Telecom Intermediate Bus Converter |
|
Use Scenario: Constant-current driver for multi-string high-power LEDs in outdoor lighting, requiring dimming and fault reporting. IC Role / Device Role / Timing Role: Average current-regulated buck controller using ICTRL and IMON for closed-loop current control and telemetry. Use Value: Provides ±3% LED current accuracy over –40°C to +125°C ambient with real-time IMON voltage feedback - enabling predictive maintenance via current drift monitoring. |
Use Scenario: Generating isolated 12V/5V rails from –48V telecom battery backup in base station power shelves. IC Role / Device Role / Timing Role: Non-isolated buck controller operating from –48V input (via auxiliary bias referenced to system ground) with SYNC input for EMI spread-spectrum alignment. Use Value: Supports –48V input with no polarity-reversal protection required; 1MHz capability reduces output filter size by 60% vs. 250kHz alternatives while meeting GR-1089 Class B emissions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3890EUFD#PBF | Dual-output, 60V input, integrated MOSFET drivers with PMBus interface; higher IQ (120µA) and larger QFN-40 package. | Supports two independent regulated outputs and digital configuration - suited for multi-rail server or networking systems requiring telemetry. | Select LTC3890EUFD#PBF only if dual-output capability, PMBus control, or higher output current (>30A) is required; not drop-in compatible due to different pinout and feature set. |
| MP24894GQZ-P | 40V max input, integrated power MOSFETs, fixed 500kHz frequency, no auxiliary bias regulator or ICTRL-based current limiting. | Targeted at cost-sensitive consumer DC/DC where board space is constrained and external gate drivers are undesirable. | Choose MP24894GQZ-P for compact, low-BOM-count 12V→5V/3.3V conversion below 8A; avoid for >40V input, programmable current limit, or auxiliary bias needs. |
Compared with LTC3890EUFD#PBF and MP24894GQZ-P, the LT3840EFE#PBF uniquely combines 60V input tolerance, integrated 7.5V auxiliary bias, and analog-programmable average current limit in a TSSOP-28 package - making it optimal for ruggedized single-output industrial and automotive converters where reliability and design simplicity outweigh digital configurability or integration density.
Availability
LT3840EFE#PBF is available at Aetrix Electronics and suitable for automotive infotainment power, industrial 48V DC-DC conversion, and LED street lighting applications requiring stable component supply, long-term lifecycle assurance, and AEC-Q200-aligned manufacturing traceability.
Supply support for LT3840EFE#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. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.
The LT3840EFE#PBF belongs to Analog Devices' Power by Linear™ family of high-voltage DC/DC controllers, designed specifically for robust, wide-input industrial and automotive power conversion where efficiency, reliability, and thermal resilience are critical.
FAQ
What is the maximum input voltage rating for the LT3840EFE#PBF?
The LT3840EFE#PBF has an absolute maximum input voltage rating of 80V on AUXVIN and VIN pins, with guaranteed operation from 2.5V to 60V. Internal OVLO protection disables switching above 60V on AUXVIN to safeguard the auxiliary bias regulator, while the main controller remains functional up to 80V transients - a key requirement for automotive load-dump survivability testing per ISO 7637-2.
How does the LT3840EFE#PBF achieve low quiescent current in battery-powered systems?
The LT3840EFE#PBF achieves 75µA quiescent current in Burst Mode by disabling both external MOSFETs and most internal circuitry during light-load sleep cycles, while retaining regulation via output capacitor hold-up. This behavior is enabled by grounding the MODE pin and relies on the internal VC clamp and FB comparator hysteresis to reinitiate switching only when output voltage droops beyond the 90% PG threshold - extending runtime in always-on IoT sensors and telematics modules.
Can the LT3840EFE#PBF be used for constant-current LED driving?
Yes, the LT3840EFE#PBF supports precise constant-current operation via its average current limit loop. Applying a voltage to ICTRL (0–1V) sets the maximum average output current, while IMON provides a 20× amplified, filtered representation of sensed current for closed-loop feedback or telemetry. The ±5% current limit accuracy over temperature and reverse-current protection make it suitable for high-reliability LED drivers in street lighting and architectural applications.
What is the purpose of the auxiliary buck-boost regulator in the LT3840EFE#PBF?
The auxiliary buck-boost regulator in the LT3840EFE#PBF generates a regulated 7.5V INTVCC supply from the same 2.5V–60V input rail, powering both internal circuitry and high-current TG/BG gate drivers. Unlike linear bias regulators, this topology avoids thermal derating at high VIN and dropout at low VIN - enabling consistent 7.5V gate drive and >90% efficiency across the full input range, critical for driving low-RDS(ON) MOSFETs in high-current applications.
Does the LT3840EFE#PBF support synchronization to an external clock?
Yes, the LT3840EFE#PBF supports external clock synchronization via the SYNC pin (Pin 4). When driven with a TTL/CMOS clock signal, the internal oscillator locks to the external frequency - provided the RT resistor sets the free-running frequency at least 15% below the minimum external clock frequency. This capability enables EMI reduction through spread-spectrum alignment and coordinated switching in multi-phase or multi-rail power systems.
LT3840EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 2.5V ~ 60V
- Frequency - Switching:
- 50kHz ~ 1MHz
- Duty Cycle (Max):
- 99%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LT3840EFE#PBF FAQ
1.How can I place an order for LT3840EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3840EFE#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 LT3840EFE#PBF reliable?
The price and inventory of LT3840EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3840EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3840EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3840EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3840EFE#PBF?
LT3840EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3840EFE#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 LT3840EFE#PBF?
For technical support, including LT3840EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3840EFE#PBF requirements.
6.How does Aetrix verify that LT3840EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3840EFE#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 LT3840EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3840EFE#PBF?
All LT3840EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3840EFE#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 LT3840EFE#PBF part is unused and in its original packaging.
Return procedure for LT3840EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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