My Inquiry
My Account
Analog Devices Inc. LT3505EDD#TRPBF
- Part No.:
- LT3505EDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LT3505EDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1.2A 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,759
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3505EDD#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 at adjustable voltages down to 780mV. It features resistor-programmable switching frequency (200kHz–3MHz), soft-start, cycle-by-cycle current limiting, and <2µA shutdown current-ideal for automotive battery regulation and industrial control supplies.
For engineers reviewing the LT3505EDD#TRPBF datasheet, LT3505EDD#TRPBF pinout, LT3505EDD#TRPBF application, or LT3505EDD#TRPBF equivalent, key selection criteria include input voltage range (3.6–36V), output current capability (1.2A), thermal performance in the 3mm × 3mm DFN-8 package, and frequency programming via RT pin resistance.
Technical Context
The LT3505EDD#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 and high efficiency across wide input ranges.
Protection features include cycle-by-cycle current limit (1.4–2.2A), undervoltage lockout (~3.35V), and active VC-pin clamping. Frequency foldback activates when FB falls below 600mV-e.g., during overload-to reduce switching frequency and prevent thermal runaway.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V operating; supports unregulated wall transformers, 24V industrial rails, and automotive batteries (40V absolute max). |
| Output Current | Up to 1.2A continuous (1.1A at VIN > 5V); limited by thermal design and inductor saturation current ≥2.2A. |
| Switching Frequency | 200kHz to 3MHz, set by RT-to-GND resistor; enables trade-off between small magnetics (high fSW) and peak efficiency (low fSW). |
| Feedback Voltage | 780mV (±15mV); sets output voltage via external resistor divider (e.g., R2 = 10kΩ, R1 = (VOUT/0.78 − 1) × R2). |
| VCE(SAT) | 350mV at 1A; minimizes conduction loss and improves efficiency in high-current, low-VOUT applications. |
| Shutdown Current | <2µA; enables true output disconnect and ultra-low quiescent power in battery-powered systems. |
| Operating Temp | –40°C to +85°C (E-grade); validated for automotive cabin and industrial ambient environments. |
Pinout & Package
The LT3505EDD#TRPBF is housed in a thermally enhanced, lead-free, 3mm × 3mm plastic DFN-8 package (DD) with exposed pad (Pin 9) that must be soldered to PCB ground for thermal and electrical integrity. θJA = 43°C/W, θJC = 5°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST (1) | Bootstrap drive supply | Provides >VIN gate drive to internal bipolar NPN switch; requires external diode + capacitor (e.g., 1N4148 + 22pF) tied between SW and BOOST. |
| SW (2) | Switch node | Connects to inductor, catch diode cathode, and BOOST capacitor; carries high di/dt switching current and requires tight layout. |
| 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; logic-low (<0.3V) enters <2µA shutdown; also provides soft-start ramp when RC-filtered. |
| GND (5) | Power and signal reference | Return path for internal circuits and feedback divider; must connect to large PCB ground plane and thermal vias under exposed pad. |
| RT (6) | Frequency programming | Resistor from RT to GND sets oscillator frequency (200kHz–3MHz); minimize stray capacitance for stable operation. |
| FB (7) | Feedback input | Regulated to 780mV; connects to resistor divider tap; bias current ≤150nA ensures accuracy with high-value dividers. |
| VC (8) | Compensation node | Internal error amplifier output; connect Type II/III compensation network (R+C+R+C) from VC to GND for loop stability. |
Key Features
| Feature | Design Value |
|---|---|
| Wide input range (3.6–36V) | Enables single-regulator solutions across automotive (cold crank to load dump), industrial (24V rail), and legacy AC/DC adapter inputs. |
| Integrated 1.4A bipolar NPN switch | Eliminates external MOSFET and driver; optimized for low VCE(SAT) and robust short-circuit handling without external sensing. |
| Resistor-programmable frequency (200kHz–3MHz) | Allows layout- and efficiency-optimized selection: 750kHz for general-purpose balance, 2.2MHz for compact 4.7µH inductors in space-constrained designs. |
| Soft-start and cycle-by-cycle current limit | Prevents input surge at startup and protects against output shorts without latch-off-critical for reliable field-deployed equipment. |
| Thermally enhanced 3mm × 3mm DFN-8 | Delivers 1.2A output with minimal board area and thermal resistance (θJA = 43°C/W), suitable for dense PCB layouts. |
Applications
| Automotive Battery Regulation | Industrial Control Supply |
|---|---|
Use Scenario: Regulating 12V/24V automotive battery (with load dump transients up to 40V) to 3.3V or 5V for infotainment microcontrollers and CAN transceivers. IC Role / Device Role / Timing Role: Primary buck converter providing isolated, stabilized low-voltage rail with built-in UVLO and short-circuit robustness. Use Value: Operates continuously across –40°C to +85°C; withstands 40V transients; <2µA shutdown extends battery life in sleep modes. | Use Scenario: Powering PLC I/O modules and sensor interfaces from noisy 24V industrial bus with EMI constraints. IC Role / Device Role / Timing Role: Step-down regulator delivering clean, regulated 5V/3.3V with low output ripple and fast transient response. Use Value: Resistor-programmable 750kHz switching avoids AM-band interference; DFN package simplifies thermal management on crowded backplanes. |
| Wall Transformer Regulation | Battery-Powered Equipment |
Use Scenario: Converting unregulated 9–24V AC/DC wall adapter outputs to stable 3.3V for embedded gateways and IoT edge nodes. IC Role / Device Role / Timing Role: High-input-range buck converter eliminating need for pre-regulation; handles wide line variation without dropout. Use Value: 3.6V UVLO prevents brownout operation; 1.2A output supports multi-rail PMIC architectures with local LDOs. | Use Scenario: Powering portable medical monitors or handheld test equipment from 2-cell Li-ion (6–8.4V) or 9V alkaline batteries. IC Role / Device Role / Timing Role: Efficient step-down regulator extending runtime while maintaining precise 3.3V/5V for ADCs and RF front-ends. Use Value: <2µA shutdown current preserves battery charge during idle; soft-start prevents inrush into large capacitive loads. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EMSE#TRPBF | Monolithic 2.5A synchronous buck; 2.7–5.5V input; fixed 3.3V/5V options; no BOOST pin required. | Lower input range; not suitable for 12V/24V automotive or industrial inputs; better for point-of-load after intermediate 5V rail. | Select LTC3605EMSE#TRPBF only if input is ≤5.5V and higher current (2.5A) is needed with synchronous rectification. |
| MP2451DT-LF-Z | 1.5A synchronous buck; 3.3–36V input; fixed 700kHz fSW; no RT pin; lower quiescent current (100µA active). | Lacks frequency programming and soft-start control; less flexible for EMI-sensitive or thermal-limited designs. | Choose MP2451DT-LF-Z for cost-sensitive, fixed-frequency applications where programmability and ultra-low shutdown current are not required. |
Compared with LTC3605EMSE#TRPBF and MP2451DT-LF-Z, the LT3505EDD#TRPBF uniquely supports 3.6–36V input with programmable frequency and bipolar switch architecture-making it optimal for ruggedized, wide-input industrial and automotive power stages where external diode tolerance and transient robustness are critical.
Availability
LT3505EDD#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial control supplies, and wall transformer regulation requiring stable component supply across extended temperature and input voltage ranges.
Supply support for LT3505EDD#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 and maintains its high-reliability analog and power management portfolio with rigorous qualification and long-term product support.
The LT3505EDD#TRPBF belongs to Linear's legacy high-voltage monolithic buck regulator family, designed specifically for robust, wide-input industrial and automotive power conversion where simplicity, fault tolerance, and thermal efficiency are prioritized over synchronous rectification.
FAQ
What is the maximum input voltage rating for the LT3505EDD#TRPBF?
The LT3505EDD#TRPBF has an absolute maximum input voltage rating of 40V on the VIN pin. Its recommended operating range is 3.6V to 36V. Exceeding 36V may trigger pulse-skipping mode above VIN(PS), but brief transients up to 40V are tolerated if the output remains regulated and inductor saturation is avoided.
Does the LT3505EDD#TRPBF require an external catch diode?
Yes, the LT3505EDD#TRPBF requires an external Schottky catch diode (e.g., MBRM140) because it uses an internal bipolar NPN switch-not a synchronous MOSFET. The diode must withstand the full input voltage (≥40V reverse rating) and conduct up to 1.2A average current; typical selection is a 1A–2A Schottky with low forward voltage.
How is the switching frequency set on the LT3505EDD#TRPBF?
The switching frequency of the LT3505EDD#TRPBF is set by connecting a 1% resistor (RT) between the RT pin (Pin 6) and ground. Values from 13.7kΩ (3MHz) to 357kΩ (200kHz) are supported per the datasheet table. Stray capacitance at the RT pin must be minimized to avoid frequency drift or instability.
What is the purpose of the BOOST pin on the LT3505EDD#TRPBF?
The BOOST pin on the LT3505EDD#TRPBF supplies a boosted gate drive voltage (typically VIN + 5V) to fully saturate the internal bipolar NPN power switch. It requires an external bootstrap circuit: a diode (e.g., 1N4148) from SW to BOOST and a capacitor (e.g., 22pF) from BOOST to SW. This reduces VCE(SAT) to 350mV at 1A, improving efficiency.
Can the LT3505EDD#TRPBF operate in shutdown mode with zero output current?
Yes, the LT3505EDD#TRPBF enters a true shutdown state with <2µA input current when the SHDN pin is pulled below 0.3V. In this mode, the internal switch is disabled, the output is disconnected from VIN, and the FB and VC pins are high-impedance-enabling complete power gating for battery-powered systems.
LT3505EDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN 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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x3)
LT3505EDD#TRPBF FAQ
1.How can I place an order for LT3505EDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3505EDD#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 LT3505EDD#TRPBF reliable?
The price and inventory of LT3505EDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3505EDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3505EDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3505EDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3505EDD#TRPBF?
LT3505EDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3505EDD#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 LT3505EDD#TRPBF?
For technical support, including LT3505EDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3505EDD#TRPBF requirements.
6.How does Aetrix verify that LT3505EDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3505EDD#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 LT3505EDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3505EDD#TRPBF?
All LT3505EDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3505EDD#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 LT3505EDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3505EDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3505EDD#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…
