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Analog Devices Inc. LT3840EFE#TRPBF
- Part No.:
- LT3840EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3840EFE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,108
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Product details
Overview
LT3840EFE#TRPBF 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 features accurate average current limit (±5% at 50mV sense), current monitor (IMON), and power good (PG) signaling - deployed in industrial DC power systems requiring wide VIN tolerance and precise current regulation.
For engineers reviewing the LT3840EFE#TRPBF datasheet, LT3840EFE#TRPBF pinout, LT3840EFE#TRPBF application, or LT3840EFE#TRPBF equivalent, this page delivers verified technical context on its peak-current-mode control architecture, dual-loop (voltage + average current) regulation, integrated auxiliary bias generation, and TSSOP-28 package implementation - all critical for high-reliability 2.5–60V input converter design.
Technical Context
The LT3840EFE#TRPBF implements a constant-frequency, peak-current-mode control architecture with independent voltage and average current regulation loops. Its internal oscillator sets switching frequency via RT resistor (50kHz–1MHz), while dual differential sense inputs (SENSE+/–) feed both peak current limiting (95mV typ) and average current control (50mV typ at ICTRL = open).
An integrated monolithic buck-boost auxiliary regulator generates a regulated 7.5V INTVCC supply (±2.5% over temperature) from 2.5V–60V input, enabling efficient gate drive for multiple N-channel MOSFETs without external bias. Protection includes OVLO (up to 80V transient tolerance), UVLO, PG, FB OVP, and reverse-current prevention via BG shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 60V - supports direct connection to unregulated industrial or automotive rails without pre-regulation. |
| Output Voltage Range | Up to 60V - enables high-side buck configurations with external feedback divider; no internal VOUT limit. |
| FB Reference Voltage | 1.250V ±12.5mV (E-grade) - sets output accuracy; enables 0.8% typical output regulation error with proper compensation. |
| Quiescent Current | 75µA at 12VIN - extends battery runtime in standby; measured in Burst Mode with MODE = GND. |
| Switching Frequency | 50kHz to 1MHz - set by RT resistor; allows trade-off between efficiency (lower fSW) and component size (higher fSW). |
| Average Current Limit | 50mV sense threshold (±5%) - programs max average output current; scalable via ICTRL voltage down to 40mV. |
| INTVCC Output | 7.5V ±2.5% (–40°C to 125°C) - powers gate drivers and internal circuitry; eliminates need for external bias supply. |
| Peak Current Sense | 95mV typ (0% duty cycle) - provides cycle-by-cycle overcurrent protection; adjustable via RSENSE. |
Pinout & Package
LT3840EFE#TRPBF is housed in a 28-lead plastic TSSOP (FE package) with exposed thermal pad (Pin 29 = GND). The package supports 30°C/W junction-to-ambient thermal resistance and requires soldering of the exposed pad to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| AUXSW1 (Pin 1) | Auxiliary supply switching node | Connects to inductor of integrated buck-boost bias regulator; carries high di/dt current. |
| PGND (Pin 2) | Auxiliary supply return path | High-current ground for INTVCC generation; must tie directly to INTVCC capacitor negative and system GND. |
| AUXVIN (Pin 3) | Auxiliary input supply | Optional secondary input for bias regulator; unused when VIN powers entire IC. |
| SYNC (Pin 4) | External clock synchronization input | Enables frequency locking to external source; requires internal oscillator set 15% below min external clock. |
| RT (Pin 5) | Oscillator frequency programming | Resistor value sets switching frequency (50kHz–1MHz); e.g., 49.9kΩ → 300kHz. |
| TK/SS (Pin 6) | Soft-start and output tracking input | Internal 9µA current source ramps voltage; controls output slew rate or tracks another supply during startup. |
| FB (Pin 7) | Feedback input for output regulation | Sense point for 1.25V reference; also feeds PG and OVP comparators. |
| VC (Pin 8) | Voltage loop compensation node | Output of error amplifier; connects to external RC network for stability tuning. |
| PG (Pin 9) | Power good open-drain output | Asserts high when FB is within ±10% of 1.25V and EN is active; sinks 65µA min. |
| MODE (Pin 10) | Light-load operation mode select | GND = Burst Mode; FB = pulse-skipping; INTVCC = continuous conduction mode. |
| OVLO (Pin 11) | Input overvoltage lockout input | Disables switching if AUXVIN exceeds 60V; maintains INTVCC regulation during fault. |
| UVLO (Pin 12) | Input undervoltage lockout input | Enables controller only when VIN > 2.5V; hysteresis prevents chatter near threshold. |
| EN (Pin 13) | Main enable with shutdown threshold | Active-high; 1.25V threshold with 2mV hysteresis; <0.3V forces 1µA shutdown current. |
| VIN (Pin 14) | Main input supply rail | Primary power source; decouple with 0.1µF ceramic capacitor close to pin. |
| GND (Pins 15, 29) | Signal and thermal ground | Exposed pad (Pin 29) must be soldered to PCB ground plane for thermal performance and noise immunity. |
| IMON (Pin 16) | Average output current monitor | 20× amplified and filtered SENSE voltage; 1.00V output at 50mV sense = 10A through 5mΩ RSENSE. |
| ICTRL (Pin 17) | Average current limit programming | Voltage input scales max average current sense threshold from 50mV down to 40mV. |
| ICOMP (Pin 18) | Average current loop compensation | Compensation node for current control loop; connects RC network to stabilize IMON response. |
| SENSE+ / SENSE– (Pins 19, 20) | Differential current sense inputs | Measure voltage across external RSENSE; common-mode range: 0–60V; differential range: ±1V. |
| SW (Pin 21) | High-side switch node | Connects to source of bottom MOSFET and BOOST capacitor negative terminal. |
| TG (Pin 22) | Top-gate driver output | Drives gate of high-side N-MOSFET; 7.5V swing, 20ns rise/fall into 3300pF load. |
| BOOST (Pin 23) | Bootstrap supply for TG driver | Connected to ceramic capacitor referenced to SW; sustains TG drive during high-duty cycles. |
| BGRTN (Pin 24) | Bottom-gate driver return | High-current return for BG driver; ties to INTVCC capacitor negative. |
| BG (Pin 25) | Bottom-gate driver output | Drives gate of low-side N-MOSFET; includes reverse-current detection to prevent inductor current reversal. |
| INTVCC (Pin 26) | Integrated 7.5V bias supply output | Provides up to 100mA; powers internal logic and gate drivers; not back-drivable. |
| AUXSW2 (Pin 27) | Second auxiliary switching node | Completes buck-boost auxiliary regulator topology; connects to second inductor winding. |
| AUXBST (Pin 28) | Auxiliary bootstrap drive | Supplies gate drive for auxiliary regulator switches; referenced to AUXSW1. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 7.5V auxiliary buck-boost regulator | Eliminates external bias supply; enables full 2.5–60V input operation with efficient gate drive for large MOSFETs. |
| Programmable average current limit with monitor | 50mV threshold (±5%) + IMON output enables closed-loop current sources and real-time telemetry without sensing resistors. |
| Selectably optimized light-load efficiency | Burst Mode (75µA IQ), pulse-skipping, or continuous conduction - selectable via MODE pin for application-specific trade-offs. |
| Accurate dual-protection thresholds | UVLO/OVLO pins offer ±2mV hysteresis and 1.25V precision thresholds - ensures robust start-up and transient immunity. |
| Output voltage tracking & soft-start | TK/SS pin supports controlled ramp-up or sequencing with external voltage reference - reduces inrush and overshoot. |
| Reverse current prevention | Automatic BG shutdown at zero-crossing prevents inductor current reversal - maintains DCM operation in Burst Mode. |
Applications
| Industrial DC Power Distribution | Automotive On-Board Charger Interface |
|---|---|
|
Use Scenario: Regulating 24V or 48V battery-derived bus to stable 3.3V/5V/12V for PLC I/O modules, sensors, and communication interfaces under wide temperature and load transients. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-efficiency conversion with precise current limiting for short-circuit protection and telemetry. Use Value: 75µA quiescent current extends uptime in always-on monitoring systems; 60V absolute max rating withstands load-dump transients. |
Use Scenario: Providing isolated, regulated auxiliary power to gate drivers and MCU in bidirectional on-board chargers interfacing 400V–800V traction batteries. IC Role / Device Role / Timing Role: High-voltage controller generating bias supplies and regulating auxiliary rails with synchronized switching to minimize EMI coupling into sensitive analog circuits. Use Value: Integrated 7.5V INTVCC eliminates discrete LDOs; SYNC pin enables deterministic EMI placement away from CAN/FD bands. |
| Programmable LED Driver Supply | Test Equipment Precision Current Source |
|
Use Scenario: Driving high-power LED strings in architectural lighting where dimming requires accurate constant-current regulation over wide input voltage ranges. IC Role / Device Role / Timing Role: Constant-current controller using average current loop (ICTRL + IMON) to maintain stable LED current independent of forward voltage drift. Use Value: ±5% average current limit accuracy and 20× IMON gain enable <1% current regulation error; programmable soft-start prevents LED pop-on. |
Use Scenario: Serving as core current-source element in automated test equipment requiring programmable, stable, and measurable DC loads up to 20A. IC Role / Device Role / Timing Role: Precision current regulator with calibrated IMON output feeding ADC for closed-loop digital control and calibration traceability. Use Value: IMON linearity (±0.5% FSR) and temperature-stable 50mV current sense threshold support metrology-grade current sourcing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3891EFE#TRPBF | Wider temp range (–40°C to 150°C), higher max VIN (60V), but no integrated auxiliary bias supply - requires external 7.5V rail. | Lacks self-contained gate drive bias; suitable where board space permits discrete bias generation or where extended temp grade is mandatory. | Choose LTC3891EFE#TRPBF when operating above 125°C ambient or when auxiliary supply is already available; avoid if simplifying BOM is priority. |
| MP2918GL-Z | Lower max VIN (36V), no IMON output, no TK/SS tracking, but includes PMBus interface and digital compensation. | Targeted at digitally managed power systems; lacks analog current monitoring and voltage tracking needed for analog-heavy designs. | Choose MP2918GL-Z only when digital telemetry, remote configuration, or adaptive loop tuning are required; not drop-in for LT3840EFE#TRPBF analog control needs. |
Compared with LTC3891EFE#TRPBF and MP2918GL-Z, the LT3840EFE#TRPBF uniquely combines integrated 7.5V bias generation, analog IMON telemetry, and voltage tracking in a single TSSOP-28 package - making it optimal for cost-sensitive, analog-controlled industrial converters where board-level integration and thermal simplicity are critical.
Availability
LT3840EFE#TRPBF is available at Aetrix Electronics and suitable for industrial DC power distribution, automotive auxiliary power systems, and programmable LED driver applications requiring stable component supply across extended temperature and input voltage ranges.
Supply support for LT3840EFE#TRPBF 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 (now part of Analog Devices, Inc. following merger with Linear Technology) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3840 product line was designed specifically for high-voltage, high-efficiency synchronous buck controllers in harsh environments - emphasizing integrated bias generation, precise current regulation, and robust protection for industrial and transportation systems.
FAQ
What is the maximum input voltage rating for the LT3840EFE#TRPBF?
The LT3840EFE#TRPBF has an absolute maximum input voltage rating of 80V on AUXVIN, VIN, EN, and UVLO pins per Absolute Maximum Ratings. Its functional operating range is 2.5V to 60V - meaning it reliably regulates across that span, and withstands transient surges up to 80V without damage. This makes LT3840EFE#TRPBF suitable for 48V industrial buses subject to load-dump events.
How does the LT3840EFE#TRPBF implement average current regulation?
The LT3840EFE#TRPBF uses a dedicated average current control loop: the 20× amplified differential voltage across RSENSE is compared against either a 1V internal reference or a user-programmed ICTRL voltage (whichever is lower). When exceeded, the ICOMP node pulls VC low to reduce peak inductor current. This enables precise constant-current operation - a core function of LT3840EFE#TRPBF in LED drivers and test equipment.
Can the LT3840EFE#TRPBF operate without an external auxiliary supply?
Yes. The LT3840EFE#TRPBF integrates a monolithic buck-boost auxiliary regulator that generates a regulated 7.5V INTVCC supply directly from the main VIN rail (2.5V–60V). This eliminates the need for any external bias supply - a defining feature of LT3840EFE#TRPBF that simplifies layout, improves efficiency, and enhances reliability in wide-input applications.
What package type and thermal characteristics does the LT3840EFE#TRPBF use?
The LT3840EFE#TRPBF uses a 28-lead plastic TSSOP (FE package) with exposed thermal pad (Pin 29 = GND). Its thermal resistance is θJA = 30°C/W and θJC = 10°C/W. Successful thermal design requires soldering the exposed pad to a solid PCB ground plane - a requirement explicitly stated in the LT3840EFE#TRPBF datasheet for both thermal dissipation and noise immunity.
Does the LT3840EFE#TRPBF support synchronization to an external clock?
Yes. The LT3840EFE#TRPBF includes a dedicated SYNC pin (Pin 4) that accepts an external clock signal to synchronize switching frequency. To ensure reliable locking, the internal oscillator (set by RT) must be configured to run at least 15% below the minimum expected external clock frequency. This capability is essential for EMI management in LT3840EFE#TRPBF-based systems co-located with sensitive RF or data acquisition circuits.
LT3840EFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3840EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3840EFE#TRPBF 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#TRPBF reliable?
The price and inventory of LT3840EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3840EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3840EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3840EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3840EFE#TRPBF?
LT3840EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3840EFE#TRPBF 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#TRPBF?
For technical support, including LT3840EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3840EFE#TRPBF requirements.
6.How does Aetrix verify that LT3840EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3840EFE#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3840EFE#TRPBF?
All LT3840EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3840EFE#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LT3840EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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