My Inquiry
My Account
Analog Devices Inc. LT3505IMS8E#TRPBF
- Part No.:
- LT3505IMS8E#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3505IMS8E#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1.2A 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,940
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3505IMS8E#TRPBF from Analog Devices (formerly Linear Technology) is a current-mode PWM step-down DC/DC converter with an integrated 1.4A bipolar NPN power switch, operating from 3.6V to 36V input and delivering up to 1.2A output current. It features resistor-programmable switching frequency (200kHz–3MHz), 780mV feedback reference, soft-start, and <2µA shutdown current-designed for automotive battery regulation, industrial control supplies, and wall transformer-derived systems.
For engineers reviewing the LT3505IMS8E#TRPBF datasheet, LT3505IMS8E#TRPBF pinout, LT3505IMS8E#TRPBF application, or LT3505IMS8E#TRPBF equivalent, key selection criteria include input voltage range (3.6–36V), output current capability (1.2A at VIN > 8V), thermal performance in MSOP-8 package, and frequency programming via RT pin resistor.
Technical Context
The LT3505IMS8E#TRPBF implements constant-frequency current-mode control using an RS flip-flop driven by a resistor-programmed oscillator. Its internal bipolar NPN switch requires BOOST pin bootstrapping for full saturation, enabling low VCE(SAT) of 350mV at 1A. Cycle-by-cycle current limiting and active VC-clamp protection ensure robustness against shorted outputs.
It integrates undervoltage lockout (~3.35V threshold), error amplifier (200µA/V transconductance, 400V/V gain), and frequency foldback triggered when FB falls below 600mV-critical for safe start-up and overload recovery. The device operates across –40°C to +125°C and supports both continuous and discontinuous conduction modes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V operating; enables direct regulation from 24V industrial rails or automotive batteries (40V absolute max). |
| Output Current | Up to 1.2A at VIN > 8V; limited by thermal design and inductor saturation in MSOP-8 package. |
| Switching Frequency | 200kHz–3MHz via RT pin resistor; higher frequencies allow smaller magnetics but reduce efficiency due to edge loss. |
| Feedback Reference | 780mV ±15mV; sets output voltage via external resistor divider (e.g., 3.3V with 69.8kΩ/11.3kΩ). |
| Shutdown Current | <2µA; enables true output disconnect and ultra-low quiescent power in battery-powered systems. |
| Power Switch VCE(SAT) | 350mV at 1A; minimizes conduction loss and improves efficiency at high load currents. |
| Operating Temperature | –40°C to +125°C (I-grade); qualified for under-hood automotive and industrial environments. |
Pinout & Package
LT3505IMS8E#TRPBF is housed in an 8-lead plastic MSOP package (MS8E) with exposed pad (Pin 9) soldered to PCB ground for thermal and electrical integrity. θJA = 40°C/W, θJC = 5°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST (1) | Bootstrap drive supply | Provides gate drive voltage > VIN to saturate internal bipolar NPN switch; requires external diode + capacitor. |
| SW (2) | Switch node | Connects to inductor, catch diode cathode, and BOOST capacitor; carries high di/dt switching current. |
| VIN (3) | Main power input | Supplies internal regulator and power switch; must be locally bypassed with ≥1µF X7R ceramic capacitor. |
| SHDN (4) | Enable/shutdown control | Logic-high (>2.3V) enables operation; tied to VIN for always-on; provides soft-start ramp when RC-filtered. |
| GND (5) | Analog & power ground | Reference for FB, VC, RT; return path for feedback divider and compensation network; connects to exposed pad. |
| RT (6) | Oscillator frequency set | Resistor-to-ground programs switching frequency (200kHz–3MHz); sensitive to stray capacitance. |
| FB (7) | Output voltage sense | Regulated to 780mV; connects to resistor divider midpoint; bias current ≤150nA affects high-R divider accuracy. |
| VC (8) | Control loop compensation | Connects external RC network to ground; error amplifier output; clamped to SHDN during soft-start. |
Key Features
| Feature | Design Value |
|---|---|
| Wide input voltage range | 3.6V–36V operation supports unregulated 24V industrial, 12V/24V automotive, and AC/DC wall adapter inputs without pre-regulation. |
| Integrated 1.4A power switch | Bipolar NPN switch with 350mV VCE(SAT) at 1A reduces conduction loss and simplifies layout vs. external MOSFET solutions. |
| Resistor-programmable frequency | 200kHz–3MHz tuning allows optimization of size (high-freq) vs. efficiency (low-freq) and EMI compliance. |
| Soft-start and shutdown | External RC on SHDN enables controlled output ramp-up; <2µA shutdown current enables true system-level power gating. |
| Short-circuit robustness | Cycle-by-cycle current limit + frequency foldback prevent thermal runaway during output shorts or heavy overloads. |
Applications
| Automotive Battery Regulation | Industrial Control Supply |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery to 3.3V or 5V for microcontrollers, CAN transceivers, and sensors in engine control units. IC Role / Device Role / Timing Role: Primary buck converter providing stable, fault-tolerant power under load dump (up to 40V transient) and cold-crank (down to 3.6V). Use Value: I-grade temperature rating (–40°C to +125°C), UVLO at 3.35V, and frequency foldback ensure reliable start-up and sustained operation in harsh automotive environments. | Use Scenario: Powering PLC I/O modules, fieldbus interfaces, and analog front-ends from 24V industrial bus rails. IC Role / Device Role / Timing Role: Isolated, high-reliability DC/DC stage converting noisy 24V supply to clean 3.3V/5V for precision analog and digital circuitry. Use Value: 36V max operating input and 40V absolute max withstand capability tolerate industrial line surges; MSOP-8 package fits space-constrained DIN-rail mount designs. |
| Wall Transformer Regulation | Battery-Powered Equipment |
Use Scenario: Converting unregulated 9–24V AC/DC wall adapter output to regulated 3.3V for embedded networking devices or IoT gateways. IC Role / Device Role / Timing Role: Efficient, compact step-down regulator eliminating need for linear post-regulators and reducing heat dissipation. Use Value: Up to 90% efficiency at 1A load (12V→3.3V, 750kHz) and tiny external components (10µH inductor, 10µF output cap) minimize BOM cost and footprint. | Use Scenario: Power management in portable test equipment, handheld meters, or medical monitors requiring long battery life. IC Role / Device Role / Timing Role: Main system regulator with ultra-low shutdown current (<2µA) and programmable frequency to balance runtime vs. noise. Use Value: Soft-start prevents inrush into large capacitive loads; 780mV reference enables precise low-voltage outputs critical for Li-ion battery–fed systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EMS8E#TRPBF | Monolithic synchronous buck; 3.6V–36V input; 1.2A; 3.5MHz max freq; 500mV ref; no BOOST pin required. | Higher efficiency (no external diode), lower quiescent current (25µA), but lacks frequency foldback and bipolar switch ruggedness. | Prefer for new designs where efficiency > robustness; not drop-in due to different pinout and control architecture. |
| TPS54202DRCT | Synchronous buck; 4.5V–28V input; 2A; 2.5MHz max freq; 0.6V ref; integrated FETs; enable/shutdown only. | Wider output current range, lower ref voltage, but narrower input range and no I-grade temp option. | Choose for cost-sensitive industrial apps with 5–24V input; verify thermal margin in MSOP-8 at 1.2A continuous. |
Compared with LTC3605EMS8E#TRPBF and TPS54202DRCT, the LT3505IMS8E#TRPBF offers superior input voltage range (3.6–36V), bipolar switch ruggedness for short-circuit survival, and built-in frequency foldback-making it uniquely suited for automotive and wide-input industrial applications where reliability under fault conditions is critical.
Availability
LT3505IMS8E#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial control supplies, and wall transformer-derived power systems requiring stable component supply across extended temperature ranges.
Supply support for LT3505IMS8E#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3505 belongs to Linear's legacy monolithic DC/DC converter family, engineered for rugged, wide-input industrial and automotive power conversion with emphasis on fault tolerance, thermal resilience, and ease of use in high-noise environments.
FAQ
What is the maximum input voltage the LT3505IMS8E#TRPBF can handle continuously?
The LT3505IMS8E#TRPBF has a continuous operating input voltage range of 3.6V to 36V. Its absolute maximum rating is 40V, but sustained operation above 36V may cause permanent damage or violate safety margins. For automotive applications with load dump transients, external clamping or foldback circuits are recommended to keep VIN within 36V during fault events. The LT3505IMS8E#TRPBF datasheet specifies 36V as the maximum recommended operating voltage.
Does the LT3505IMS8E#TRPBF require an external catch diode?
Yes, the LT3505IMS8E#TRPBF requires an external Schottky catch diode (e.g., ON Semiconductor MBRM140) connected between SW and GND. Unlike synchronous buck converters, it uses an internal bipolar NPN switch and external diode for freewheeling. The diode must withstand the full input voltage (≥40V reverse rating) and conduct up to 1.2A peak current. Omitting the diode will cause catastrophic failure during switch-off transitions. The LT3505IMS8E#TRPBF cannot operate without this component.
How is the switching frequency set on the LT3505IMS8E#TRPBF?
The switching frequency of the LT3505IMS8E#TRPBF is set by connecting a 1% tolerance resistor (RT) between the RT pin (Pin 6) and GND. Values from 13.7kΩ (3MHz) to 357kΩ (200kHz) program the oscillator across its full range. The RT pin bias voltage is ~0.5V, so current draw is minimal. Layout best practice requires minimizing trace length and capacitance at the RT pin to avoid frequency instability. The LT3505IMS8E#TRPBF datasheet includes a full table correlating resistance to frequency.
What is the purpose of the BOOST pin on the LT3505IMS8E#TRPBF?
The BOOST pin (Pin 1) on the LT3505IMS8E#TRPBF provides a boosted gate drive voltage (>VIN) to fully saturate the internal bipolar NPN power switch, minimizing VCE(SAT) and conduction loss. It requires an external bootstrap capacitor (e.g., 22pF–100pF) and Schottky diode connected from SW to BOOST. Without proper BOOST circuitry, the switch operates in linear mode, causing excessive heating and potential failure. This architecture distinguishes the LT3505IMS8E#TRPBF from MOSFET-based buck regulators.
Can the LT3505IMS8E#TRPBF be used in automotive applications?
Yes, the LT3505IMS8E#TRPBF is qualified for automotive use: its I-grade version (denoted by "I" in part number) is specified from –40°C to +125°C junction temperature and includes features essential for automotive systems-including 36V operating input (withstands 24V nominal + load dump), UVLO at 3.35V (ensures start-up during cold crank), and frequency foldback for overload protection. It is commonly deployed in body control modules, infotainment power supplies, and sensor hubs. The LT3505IMS8E#TRPBF meets AEC-Q200 stress test guidelines when properly applied.
LT3505IMS8E#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.6V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 0.78V
- Voltage - Output (Max):
- 33.84V
- Current - Output:
- 1.2A
- Frequency - Switching:
- 200kHz ~ 3.01MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP-EP
LT3505IMS8E#TRPBF FAQ
1.How can I place an order for LT3505IMS8E#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3505IMS8E#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 LT3505IMS8E#TRPBF reliable?
The price and inventory of LT3505IMS8E#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3505IMS8E#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3505IMS8E#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3505IMS8E#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3505IMS8E#TRPBF?
LT3505IMS8E#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3505IMS8E#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 LT3505IMS8E#TRPBF?
For technical support, including LT3505IMS8E#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3505IMS8E#TRPBF requirements.
6.How does Aetrix verify that LT3505IMS8E#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3505IMS8E#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 LT3505IMS8E#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3505IMS8E#TRPBF?
All LT3505IMS8E#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3505IMS8E#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 LT3505IMS8E#TRPBF part is unused and in its original packaging.
Return procedure for LT3505IMS8E#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3505IMS8E#TRPBF Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
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…
