My Inquiry
My Account
Analog Devices Inc. LT3845EFE#PBF
- Part No.:
- LT3845EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3845EFE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:326
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3845EFE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, synchronous current-mode step-down controller for medium-to-high-power DC/DC conversion. It operates from 4V to 60V input, delivers up to 36V output, supports adjustable switching frequency from 100kHz to 500kHz, and features 1% output voltage regulation accuracy - used in 48V telecom power supplies and industrial control systems.
For engineers reviewing the LT3845EFE#PBF datasheet, LT3845EFE#PBF pinout, LT3845EFE#PBF application, or LT3845EFE#PBF equivalent, key selection considerations include its 120μA no-load quiescent current, reverse inductor current inhibit for light-load efficiency, adaptive nonoverlap gate drive, programmable soft-start, and thermally enhanced 16-lead TSSOP package with exposed SGND pad.
Technical Context
The LT3845EFE#PBF implements a fixed-frequency, current-mode control architecture with external N-channel MOSFETs. Its oscillator is programmable via fSET resistor or synchronizable to an external clock up to 600kHz, enabling noise-sensitive system integration. The error amplifier (transconductance: 270–410 μS) drives the VC pin to set peak inductor current per cycle.
It integrates adaptive nonoverlap circuitry between TG and BG drivers to prevent shoot-through, and includes dedicated sense inputs (SENSE+, SENSE–) with ±100mV current limit threshold and 10mV reverse-current offset. Burst Mode® operation is controlled by BURST_EN, enabling 120μA quiescent current at no load while maintaining regulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 60V - supports wide-range industrial/automotive inputs; minimum start-up at 7.5V |
| Output Voltage Range | Up to 36V - enables high-step-down ratios (e.g., 48V→12V) with external FETs |
| Switching Frequency | 100kHz–500kHz (adjustable), sync-capable up to 600kHz - balances size, efficiency, and EMI |
| Quiescent Current | 120μA in Burst Mode - extends battery life in standby; drops to 10μA in shutdown |
| Regulation Accuracy | ±1% over line/load/temperature - ensures stable output under dynamic conditions |
| Current Sense Threshold | ±100mV across SENSE+/- - sets precise overcurrent protection independent of duty cycle |
| Gate Drive Capability | TG/BG drivers support large N-MOSFETs; 9.8V typical bootstrapped "ON" voltage - ensures full enhancement |
Pinout & Package
LT3845EFE#PBF is housed in a 16-lead thermally enhanced plastic TSSOP package with exposed lead-frame pad (Pin 17) internally connected to SGND. The exposed pad must be soldered to PCB ground for thermal performance and low-noise reference integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input supply rail | Accepts 4V–60V; powers internal VCC regulator; requires local 0.1μF decoupling to SGND |
| SHDN | Enable/disable control input | 1.35V rising threshold with 120mV hysteresis; pulls IC into 10μA shutdown when <0.7V |
| CSS | Soft-start timing node | Charged by internal 2μA current source; controls output voltage slew rate during startup |
| BURST_EN | Burst Mode & reverse-current enable | <0.5V enables both functions; 0.5–2.5V enables reverse-current only; >2.5V disables both |
| VFB | Feedback reference input | Compares against 1.231V internal reference; sets output voltage via external resistor divider |
| VC | Error amplifier output | Drives current-sense comparator threshold; clamped during Burst Mode to limit negative swing |
| SYNC | External clock synchronization input | Accepts 100–600kHz external clock; not available on PDIP variant; requires RSET bias |
| fSET | Oscillator frequency programming | Resistor-connected pin sets nominal frequency; required even when SYNC is active |
| BOOST | Bootstrapped gate drive supply | Supplies TG driver; referenced to SW; max voltage = VIN + VCC; requires ≥0.1μF ceramic cap |
| TG | Top N-MOSFET gate driver output | Bootstrapped high-side driver; fast rise/fall (50ns); requires short/wide trace to minimize inductance |
| SW | Switch node connection | High dv/dt node; connects to MOSFET source and BOOST capacitor; absolute max = –2V transient |
| VCC | Internal bias supply decoupling node | 8V regulated output; powers most internal circuitry; decouple with ≥1μF ceramic to PGND |
| BG | Bottom N-MOSFET gate driver output | Low-side driver; 0.1V typical "OFF" voltage; fast switching; connect directly to MOSFET gate |
| PGND | Power ground return | High-current return for VCC regulator and BG driver; tie to –VOUT side of input capacitor |
| SENSE+ | Positive current sense input | Connects to inductor side of sense resistor; common-mode range: 0–36V |
| SENSE– | Negative current sense input | Connects to output side of sense resistor; differential threshold = ±100mV |
| SGND | Signal ground reference | Low-noise analog ground; tie to –VOUT side of output capacitors; isolate from PGND |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive nonoverlap gate drive | Prevents simultaneous conduction of TG/BG (200ns TG→BG, 150ns BG→TG), eliminating shoot-through losses |
| Reverse inductor current inhibit | Disables BG when inductor current nears zero - enables discontinuous mode and improves light-load efficiency |
| Programmable soft-start | Controlled output ramp via CSS capacitor; prevents inrush current and output overshoot during startup |
| Burst Mode® operation | Reduces total input current to 120μA at no load while maintaining regulation - critical for battery backup systems |
| Wide-input, high-efficiency architecture | Onboard VCC regulator simplifies biasing; supports external VCC/VBOOST sourcing to cut dissipation at high VIN |
Applications
| 48V Telecom Power Supply | Industrial Control System |
|---|---|
Use Scenario: Converting -48V or +48V backplane voltage to 12V/5V for base station cards and remote radio units. IC Role / Device Role / Timing Role: Primary step-down controller managing synchronous buck stage with external 100V MOSFETs. Use Value: 60V absolute max input rating and 120μA Burst Mode current ensure reliability and standby efficiency in distributed telecom infrastructure. |
Use Scenario: Powering PLC I/O modules and fieldbus interfaces in harsh factory environments with fluctuating 24V–48V DC rails. IC Role / Device Role / Timing Role: High-reliability DC/DC controller delivering regulated 3.3V/5V/12V outputs with UVLO and overcurrent protection. Use Value: 1% regulation accuracy and –40°C to 125°C operating range guarantee stable operation across temperature extremes and load transients. |
| Avionics Power Converter | Heavy Equipment Battery System |
Use Scenario: Generating 28V or 270V-derived intermediate rails in airborne power distribution units with strict EMI limits. IC Role / Device Role / Timing Role: Synchronizable controller (via SYNC pin) enabling spread-spectrum or fixed-frequency coordination with other converters. Use Value: External clock synchronization up to 600kHz allows deterministic noise placement and compliance with DO-160 conducted emissions requirements. |
Use Scenario: Converting 12V/24V/42V vehicle battery voltage to stable 5V/3.3V for engine control units and telematics modules. IC Role / Device Role / Timing Role: Robust controller supporting cold-crank (4V) and load-dump (60V) conditions without latch-up or reset. Use Value: 4V–60V input range, 10μA shutdown current, and reverse-current inhibit extend runtime and protect against regenerative braking energy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3891EFE#PBF | Wider input range (4.5V–60V), integrated LDO for VCC, dual-output capability, higher gate drive current (1.2A sink/source) | Supports dual-phase or dual-output designs; better suited for multi-rail avionics or automotive ADAS systems | Select LTC3891EFE#PBF when needing dual outputs or integrated VCC LDO; LT3845EFE#PBF remains optimal for single-output cost-sensitive telecom use. |
| LM5116PWPR | Lower max input (100V), no Burst Mode, higher quiescent current (1.5mA), no reverse-current inhibit, SOIC-20 package | Targeted at high-input industrial converters where light-load efficiency is secondary to ruggedness and layout simplicity | Choose LM5116PWPR for ultra-high VIN (>60V) or where external sync is unnecessary; LT3845EFE#PBF offers superior light-load behavior and thermal performance in TSSOP. |
Compared with LTC3891EFE#PBF and LM5116PWPR, the LT3845EFE#PBF provides the best balance of ultra-low quiescent current (120μA), reverse-current inhibit, and compact thermally enhanced TSSOP packaging - making it ideal for space-constrained, battery-backed, or high-efficiency single-output applications.
Availability
LT3845EFE#PBF is available at Aetrix Electronics and suitable for 48V telecom power supplies, industrial control systems, avionics converters, and heavy equipment battery management requiring stable component supply across extended temperature ranges.
Supply support for LT3845EFE#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 its high-performance power management portfolio. Linear's legacy design rigor and precision analog expertise define the LT product family.
The LT3845EFE#PBF belongs to Linear's high-voltage synchronous buck controller product line, engineered specifically for efficient, robust DC/DC conversion in telecom, industrial, and transportation systems operating from 4V to 60V input rails.
FAQ
What is the maximum input voltage rating for the LT3845EFE#PBF?
The LT3845EFE#PBF has an absolute maximum input voltage (VIN) rating of 65V, with continuous operation supported from 4V to 60V. Its minimum start-up voltage is 7.5V, though operation down to 4V is possible if VCC is externally biased above 6.5V - a key feature enabling cold-crank compatibility in automotive applications. This specification is confirmed in the Absolute Maximum Ratings table and Electrical Characteristics section of the official datasheet.
Does the LT3845EFE#PBF support external clock synchronization?
Yes, the LT3845EFE#PBF supports external clock synchronization via its SYNC pin, accepting input frequencies from 100kHz to 600kHz. When using SYNC, the internal oscillator's RSET resistor must still be installed and configured to run ~10–25% below the external clock frequency to ensure reliable locking. Note that the SYNC pin is not present on the PDIP (N-package) variant - this functionality is exclusive to the TSSOP (FE-package) version, including LT3845EFE#PBF.
How does the reverse inductor current inhibit function work in the LT3845EFE#PBF?
The LT3845EFE#PBF detects near-zero inductor current via its SENSE+ and SENSE– inputs and disables the bottom gate (BG) driver to prevent reverse conduction - improving light-load efficiency. This function is enabled when BURST_EN is ≤0.5V (Burst Mode active) or between 0.5V and 2.5V (Burst Mode disabled). A built-in 10mV positive offset at the sense inputs prevents false triggering. The feature is confirmed in the Features list, Applications Information section, and Typical Performance Characteristics (Figure 3845 G13).
What is the purpose of the exposed pad on the LT3845EFE#PBF package?
The exposed pad on the LT3845EFE#PBF's 16-lead TSSOP package is internally connected to SGND and must be soldered to the PCB ground plane. It serves two critical roles: (1) lowering thermal resistance (θJC = 10°C/W) to improve power dissipation handling, and (2) providing a low-impedance, low-noise signal ground reference for sensitive analog circuits like the error amplifier and current sense amplifier - directly impacting regulation accuracy and EMI performance.
Can the LT3845EFE#PBF operate with an input voltage below 7.5V?
Yes, the LT3845EFE#PBF can operate with VIN as low as 4V, but only if the VCC pin is externally biased above 6.5V - bypassing the internal VIN-to-VCC linear regulator. The 7.5V minimum start-up voltage applies solely to autonomous start-up using the onboard regulator. Once running, the IC sustains operation down to 4V when VCC is supplied externally (e.g., from the converter output), a capability explicitly documented in Note 4 of the datasheet and verified in the Applications Information section.
LT3845EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 60V
- Frequency - Switching:
- 300kHz
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3845EFE#PBF FAQ
1.How can I place an order for LT3845EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3845EFE#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 LT3845EFE#PBF reliable?
The price and inventory of LT3845EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3845EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3845EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3845EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3845EFE#PBF?
LT3845EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3845EFE#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 LT3845EFE#PBF?
For technical support, including LT3845EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3845EFE#PBF requirements.
6.How does Aetrix verify that LT3845EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3845EFE#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 LT3845EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3845EFE#PBF?
All LT3845EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3845EFE#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 LT3845EFE#PBF part is unused and in its original packaging.
Return procedure for LT3845EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3845EFE#PBF Tags
-
UCC28C45DR
Texas Instruments
-
UCC28C40DR
Texas Instruments
-
UCC28C43DR
Texas Instruments
-
ZXSC410E6TA
Diodes Incorporated
-
LM3524DMX/NOPB
Texas Instruments
-
LM3489MMX/NOPB
Texas Instruments
-
MIC2102YML-TR
Microchip Technology
-
LM5148RGYR
Texas Instruments
-
TL598CDR
Texas Instruments
-
LM5155DSSR
Texas Instruments
-
LM25085MYX/NOPB
Texas Instruments
-
UCC2813DTR-0
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
