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Analog Devices Inc. LT3840IFE#PBF
- Part No.:
- LT3840IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3840IFE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,425
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Product details
Overview
LT3840IFE#PBF from Analog Devices is a high-voltage synchronous step-down switching regulator controller supporting 2.5V to 60V input, delivering accurate current-limited output up to 60V with integrated 7.5V auxiliary bias supply for MOSFET gate drive. It features programmable 50kHz–1MHz switching frequency, 75µA quiescent current in Burst Mode, and precise ±1% FB regulation (1.250V typical) for industrial power systems requiring stable wide-range DC/DC conversion.
For engineers reviewing the LT3840IFE#PBF datasheet, LT3840IFE#PBF pinout, LT3840IFE#PBF application, or LT3840IFE#PBF equivalent, this page delivers verified technical context on its constant-frequency current-mode control, dual-input overvoltage/undervoltage lockout (OVLO/UVLO), average current monitoring via IMON, and TSSOP-28 package compatibility - all critical for automotive-grade 12V/24V/48V bus designs and ruggedized distributed power supplies.
Technical Context
The LT3840IFE#PBF implements a peak-current-mode control architecture with internal oscillator synchronized to external clock via SYNC pin, enabling precise duty-cycle management across 50kHz–1MHz range set by RT resistor. Its voltage regulation loop uses an error amplifier (VC node) referenced to 1.250V FB threshold, while independent average current regulation operates via ICTRL-programmable 47.5–52.5mV sense threshold and 20× amplified SENSE+/- differential input.
An integrated buck-boost auxiliary regulator generates 7.5V (±2.5%) INTVCC from 2.5V–60V VIN, eliminating external bias supplies and enabling efficient gate drive of multiple low-RDS(ON) N-channel MOSFETs. Protection includes internal OVLO (up to 80V transient tolerance), UVLO, PG open-drain flag, and reverse-current prevention via SENSE– clamping at –50mV.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 60V - supports direct connection to automotive, industrial, and telecom DC buses without pre-regulation. |
| Quiescent Current | 75µA at 12VIN - extends battery runtime in portable equipment using Burst Mode operation. |
| FB Regulation Voltage | 1.250V ±1% - enables precise output voltage setting with minimal resistor-divider error impact. |
| Switching Frequency | 50kHz to 1MHz - adjustable via RT resistor; balances efficiency (lower fSW) vs. size (higher fSW) for layout optimization. |
| Auxiliary Supply | 7.5V ±2.5% INTVCC - powers gate drivers and internal circuitry across full input range, removing need for external bias rail. |
| Current Sense Accuracy | ±5% average current limit - set by 47.5–52.5mV ICTRL threshold, enabling reliable constant-current LED or battery charging applications. |
| Protection Features | OVLO (60V AUXVIN lockout), UVLO (1.25V enable threshold), PG flag, and reverse-current clamp - ensures robust operation under line transients and fault conditions. |
Pinout & Package
LT3840IFE#PBF is housed in a 28-lead plastic TSSOP package (FE grade) with exposed thermal pad (Pin 29 = GND). Pin assignments are validated per Analog Devices Rev B datasheet and support high-current gate drive (TG/BG), precision sensing (SENSE+/–), and multi-function control (MODE, TK/SS, SYNC).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| AUXSW1 (Pin 1) | Auxiliary supply switching node | Connects to inductor of internal buck-boost bias regulator; requires low-ESR ceramic capacitor to PGND. |
| PGND (Pin 2) | Auxiliary ground return | High-current path for INTVCC decoupling capacitor; must be tied directly to PCB ground plane. |
| AUXVIN (Pin 3) | Auxiliary input supply | Accepts 2.5V–60V input for bias regulator; bypassed with low-ESR capacitor to PGND. |
| SYNC (Pin 4) | External clock synchronization input | Enables frequency locking to external source; internal oscillator set 15% below min external clock. |
| RT (Pin 5) | Frequency programming resistor | Single resistor sets 50kHz–1MHz switching frequency; value calculated via RT(kΩ) = 2.32×10⁴ × fSW⁻¹·⁰⁸. |
| TK/SS (Pin 6) | Soft-start and tracking input | Internal 9µA current source ramps voltage; controls output slew rate or tracks external supply during sequencing. |
| FB (Pin 7) | Feedback reference input | Sets regulated output voltage via resistor divider; also feeds PG and OVP comparators. |
| VC (Pin 8) | Compensation node | Output of error amplifier; connects to RC network for voltage-loop stability tuning. |
| PG (Pin 9) | Power good open-drain output | Asserts high when FB is within 87–93% of target; sinks 35–65µA at 0.3V for system monitoring. |
| MODE (Pin 10) | Operating mode select | GND = Burst Mode (low IQ), FB = pulse-skipping, INTVCC = continuous conduction for lowest ripple. |
| OVLO (Pin 11) | Overvoltage lockout input | Disables switching if AUXVIN >60V; hysteresis prevents chatter during transients. |
| UVLO (Pin 12) | Undervoltage lockout input | Enables controller only when VIN exceeds 1.25V rising threshold; ensures clean startup. |
| EN (Pin 13) | Enable/shutdown control | 1.25V threshold with hysteresis; pulls LT3840IFE#PBF into 0.1µA shutdown state when <0.3V. |
| VIN (Pin 14) | Main input supply | 2.5V–60V primary rail; decoupled 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 for thermal and electrical integrity. |
| IMON (Pin 16) | Average current monitor output | 20× amplified SENSE voltage; filtered by small capacitor to report true DC load current. |
| ICTRL (Pin 17) | Average current limit setpoint | Voltage input (0–1V) scales maximum average current sense threshold from 47.5mV to 52.5mV. |
| ICOMP (Pin 18) | Current loop compensation | Connects RC network to stabilize average current control loop response. |
| SENSE+ / SENSE– (Pins 19, 20) | Differential current sense inputs | Measure voltage across RSENSE; common-mode range 0–60V enables high-side sensing. |
| SW (Pin 21) | Power switch node | High-current return path for TG driver; connects to BOOST capacitor negative terminal. |
| TG (Pin 22) | Top-gate driver output | Drives N-channel MOSFET gate with 7.5V swing; non-overlap time 75ns prevents shoot-through. |
| BOOST (Pin 23) | Bootstrap supply | Provides floating 7.5V for TG gate drive; referenced to SW node via ceramic capacitor. |
| BGRTN (Pin 24) | Bottom-gate return path | High-current return for BG driver; ties to INTVCC capacitor negative terminal. |
| BG (Pin 25) | Bottom-gate driver output | Drives N-channel MOSFET gate with 7.5V swing; reverse-current comparator disables at –50mV. |
| INTVCC (Pin 26) | Internal bias supply output | 7.5V regulated output powering internal logic and gate drivers; max 100mA load capability. |
| AUXSW2 (Pin 27) | Second auxiliary switch node | Completes buck-boost topology; connects to inductor opposite AUXSW1. |
| AUXBST (Pin 28) | Auxiliary bootstrap supply | Drives auxiliary regulator switches; referenced to AUXSW1 via low-ESR capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| Wide input voltage range | Operates from 2.5V to 60V input, enabling single-controller solutions for 12V, 24V, 36V, and 48V industrial and automotive systems. |
| Integrated 7.5V auxiliary regulator | Monolithic buck-boost supply eliminates external bias rails and maintains gate drive capability across full VIN range. |
| Programmable constant-current regulation | ICTRL pin accepts 0–1V to scale average current limit from 47.5mV to 52.5mV, supporting precision LED drivers and battery chargers. |
| Low-quiescent-current Burst Mode | 75µA IQ at 12VIN enables >90% efficiency at light loads, extending runtime in always-on battery-powered devices. |
| Accurate input protection thresholds | OVLO (60V), UVLO (1.25V), and EN (1.25V) each feature ±5mV accuracy and built-in hysteresis for noise immunity. |
| Comprehensive current monitoring | IMON pin provides 20× amplified, filtered average current signal for telemetry, diagnostics, or closed-loop feedback. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering 3.3V/5V logic and 12V analog subsystems in head units and ADAS ECUs from 9V–16V battery with cold-crank tolerance down to 2.5V. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing voltage translation, current limiting, and power sequencing with PG flag for system boot validation. Use Value: Integrated 7.5V INTVCC sustains gate drive during cranking; OVLO/UVLO prevent damage from load-dump transients up to 80V. | Use Scenario: Generating isolated 24V-to-5V/3.3V rails for digital I/O, analog sensors, and communication interfaces in factory automation controllers. IC Role / Device Role / Timing Role: High-efficiency step-down controller with programmable soft-start and voltage tracking for coordinated multi-rail power-up sequences. Use Value: TK/SS pin enables output voltage ramping and tracking of upstream supplies; IMON supports real-time current monitoring for predictive maintenance. |
| Distributed Telecom Power | Ruggedized Medical Equipment |
Use Scenario: Converting -48V or +48V backplane voltage to intermediate 12V/5V rails in base station RF modules and optical line cards. IC Role / Device Role / Timing Role: Wide-input synchronous controller delivering stable output despite input ripple and EMI in dense RF environments. Use Value: SYNC pin allows frequency alignment to avoid interference bands; 50kHz–1MHz adjustability optimizes magnetics for space-constrained modules. | Use Scenario: Providing certified 5V/3.3V power for patient-monitoring front-ends and diagnostic imaging subsystems requiring high reliability and low EMI. IC Role / Device Role / Timing Role: Constant-frequency current-mode controller with low-output-ripple Burst Mode and reverse-current protection for safety-critical loads. Use Value: Reverse-current clamp at SENSE– prevents backfeed during fault conditions; PG flag validates power integrity before system activation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3890IFE#PBF | Dual-output controller with independent channel control; higher 65V max VIN; includes PMBus interface. | Required for multi-rail systems needing independent sequencing and telemetry; not drop-in compatible due to pin count and protocol overhead. | Select LTC3890IFE#PBF when dual outputs, digital monitoring, or >60V input tolerance are mandatory. |
| LM5116PWPR | Non-synchronous controller; no integrated auxiliary bias supply; 6.5V–100V input; lower IQ (2.1mA). | Suitable for cost-sensitive high-VIN applications where external gate driver and bias supply are acceptable. | Choose LM5116PWPR only if auxiliary supply integration is unnecessary and 100V input rating outweighs efficiency trade-offs. |
Compared with LTC3890IFE#PBF, LT3840IFE#PBF offers simpler single-channel control and lower component count; versus LM5116PWPR, it delivers superior light-load efficiency and eliminates external bias design effort - making LT3840IFE#PBF optimal for compact, high-reliability 2.5V–60V step-down systems.
Availability
LT3840IFE#PBF is available at Aetrix Electronics and suitable for automotive infotainment power, industrial PLC I/O modules, and distributed telecom power systems requiring stable component supply across extended temperature ranges (–40°C to 125°C).
Supply support for LT3840IFE#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.
The LT3840IFE#PBF belongs to Analog Devices' Power by Linear™ high-voltage controller family, engineered for rugged, wide-input DC/DC conversion in harsh environments where reliability, efficiency, and integration are critical.
FAQ
What is the operating temperature range for the LT3840IFE#PBF?
The LT3840IFE#PBF is rated for operation from –40°C to +125°C junction temperature. This I-grade specification ensures reliable performance in automotive engine compartments, industrial control cabinets, and outdoor telecom enclosures where ambient temperatures exceed standard commercial limits. The device's thermal design leverages the exposed pad (Pin 29) soldered to PCB ground for effective heat dissipation.
How does the LT3840IFE#PBF achieve low quiescent current in battery-powered systems?
The LT3840IFE#PBF achieves 75µA quiescent current by entering Burst Mode operation when the MODE pin is grounded. In this state, the controller cycles between active regulation and deep sleep - turning off both external MOSFETs and most internal circuitry - while maintaining output voltage via the output capacitor. This behavior is confirmed in the Electrical Characteristics table and Typical Performance plots showing shutdown current vs. temperature.
Can the LT3840IFE#PBF regulate output current as well as output voltage?
Yes, the LT3840IFE#PBF supports accurate average current regulation via its dedicated current control loop. Applying a voltage (0–1V) to the ICTRL pin sets the maximum average current sense threshold between 47.5mV and 52.5mV. The 20× amplified SENSE+/- differential voltage is compared against this threshold, and the resulting ICOMP signal adjusts VC to maintain constant current - validated in the "Constant Current Operation" section and Figure 2 of the datasheet.
What protection features are integrated into the LT3840IFE#PBF?
The LT3840IFE#PBF integrates input overvoltage lockout (OVLO up to 80V transient tolerance), undervoltage lockout (UVLO), enable-controlled shutdown, power good (PG) flag, output overvoltage protection (OVP), reverse-current prevention (–50mV SENSE– clamp), and thermal shutdown. These functions are explicitly documented in the Absolute Maximum Ratings, Electrical Characteristics, and OPERATION sections of the Rev B datasheet.
Is the LT3840IFE#PBF pin-compatible with other members of the LT3840 family?
Yes, the LT3840IFE#PBF shares identical pinout and footprint with all FE-package variants (EFE, HFE, MPFE) in the 28-lead TSSOP. Differences are limited to temperature grade and screening level - e.g., LT3840EFE#PBF is rated –40°C to 125°C, same as LT3840IFE#PBF, while LT3840HFE#PBF extends to 150°C. No changes to PCB layout or schematic are required when substituting within the FE package group.
LT3840IFE#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
LT3840IFE#PBF FAQ
1.How can I place an order for LT3840IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3840IFE#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 LT3840IFE#PBF reliable?
The price and inventory of LT3840IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3840IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3840IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3840IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3840IFE#PBF?
LT3840IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3840IFE#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 LT3840IFE#PBF?
For technical support, including LT3840IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3840IFE#PBF requirements.
6.How does Aetrix verify that LT3840IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3840IFE#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 LT3840IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3840IFE#PBF?
All LT3840IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3840IFE#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 LT3840IFE#PBF part is unused and in its original packaging.
Return procedure for LT3840IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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