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Analog Devices Inc. LT3500IDD#TRPBF
- Part No.:
- LT3500IDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Regulators - Linear + Switching
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LT3500IDD#TRPBF.pdf
- Description:
- IC REG DL BUCK/LINEAR 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,666
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Product details
Overview
LT3500IDD#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 2A step-down DC/DC converter with integrated linear regulator controller, operating from 3V to 36V input and delivering adjustable output down to 0.8V. It features current-mode PWM control, 250kHz–2.2MHz resistor-programmable switching frequency, soft-start/tracking, and power-good monitoring - enabling dual-output regulation in automotive battery, industrial control, and wall-adapter applications.
For engineers reviewing the LT3500IDD#TRPBF datasheet, LT3500IDD#TRPBF pinout, LT3500IDD#TRPBF application, or LT3500IDD#TRPBF equivalent, key selection criteria include its –40°C to 125°C guaranteed junction temperature range, 12-Lead 3mm × 3mm DFN package with exposed GND pad, 2.3A internal NPN switch peak current, and dual feedback architecture supporting synchronous dual-rail regulation.
Technical Context
The LT3500IDD#TRPBF integrates two independent regulation paths: a current-mode buck converter with cycle-by-cycle overcurrent protection and an auxiliary linear regulator driver (LDRV) referenced to a matched 0.8V LFB input. Its oscillator supports both resistor-set (RT/SYNC to GND) and external synchronization modes, with automatic slope compensation retention during sync.
Control logic includes a power-on reset (POR) latch that initiates soft-start by discharging the SS pin, a VC pin serving as transconductance amplifier output and current clamp point, and complementary open-collector PG/PG outputs with 30mV hysteresis tied to FB and LFB thresholds.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 36V operating; 40V absolute max - supports direct connection to automotive batteries and unregulated 24V industrial rails without pre-regulation. |
| Switch Peak Current | 2.3A typical (DD package) - enables 2A continuous output with margin for transient loads and thermal derating in 3mm × 3mm DFN. |
| Switching Frequency | 250kHz to 2.2MHz, adjustable via RT/SYNC resistor or external clock - allows optimization of inductor size vs. efficiency across wide VIN/VOUT combinations. |
| Feedback Reference | 0.8V ±1.2% over –40°C to 125°C - ensures stable output regulation across full automotive temperature range with minimal drift. |
| Shutdown Current | 12μA typical - enables ultra-low-power sleep mode in battery-powered systems without external enable circuitry. |
| LDRV Output Capability | 13mA max, 0.8V LFB reference - supports driving external high-current PNP/NPN pass transistors for linear post-regulation or low-noise bias supplies. |
| Power Good Threshold | 90% of nominal FB/LFB voltage (0.72V), 30mV hysteresis - provides reliable system-level power sequencing and fault detection without external comparators. |
Pinout & Package
LT3500IDD#TRPBF is housed in a thermally enhanced 12-lead 3mm × 3mm plastic DFN package (DD) with exposed GND pad (Pin 13), requiring soldering to PCB for thermal and electrical integrity. θJA = 45°C/W, θJC(PAD) = 10°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main power input | Powers internal bias circuits and connects to collectors of internal NPN switch and LDRV transistor; requires local high-dI/dt decoupling. |
| SW | Switch emitter node | Connects to inductor and catch diode cathode; swings below ground during off-time - mandates close-proximity Schottky diode and ground return path. |
| BST | Bootstrap supply | Drives internal NPN base above VIN via external capacitor/diode; minimum 2.2V boost voltage required for full switch saturation. |
| FB | Switcher feedback input | Negative input of buck error amplifier; regulated to 0.8V; bias current flows out - sets primary output voltage via resistor divider. |
| LFB | Linear regulator feedback | Negative input of linear error amplifier; regulated to 0.8V (matched to FB); enables tracking or independent secondary output regulation. |
| LDRV | Linear driver output | Emitter of internal NPN; configured as linear regulator output or external pass transistor driver; 13mA max sink/source capability. |
| PG / PG | Complementary power-good | Open-collector NPN outputs; PG sinks when FB/LFB < 0.72V; PG sinks when FB/LFB > 0.72V - supports active-high or active-low system monitoring. |
| SHDN | Enable/shutdown control | Active-high input; 0.76V threshold with 2μA hysteresis - provides precise undervoltage lockout and low-quiescent shutdown (12μA). |
| SS | Soft-start/tracking control | Controls ramp rate of both switcher and linear outputs via external capacitor; enables output voltage tracking and eliminates inrush current. |
| VC | Error amplifier output | Transconductance amplifier output and current limit clamp point; used for loop compensation and overload foldback behavior. |
| RT/SYNC | Frequency setting/sync input | Accepts resistor-to-GND for 250kHz–2.2MHz operation or external clock signal (250kHz–2.5MHz) on rising edge - retains slope compensation during sync. |
Key Features
| Feature | Design Value |
|---|---|
| Dual regulation architecture | Simultaneous buck conversion (up to 2A) and linear regulation control (13mA LDRV) with matched 0.8V references - enables compact dual-rail power supplies with tight tracking. |
| Thermally robust DFN package | 12-lead 3mm × 3mm DFN with exposed GND pad (θJC = 10°C/W) - delivers 2.3A switch current capability while maintaining ≤125°C junction under typical industrial loads. |
| Programmable soft-start & tracking | Single SS pin controls ramp rate for both outputs via external capacitor - eliminates input surge and enables seamless power sequencing between VOUT1 and VOUT2. |
| Robust protection suite | Cycle-by-cycle current limit, frequency foldback during overload, thermal shutdown, and short-circuit protection across full 3V–40V input range - ensures reliability in harsh environments. |
| Automotive-grade temperature rating | –40°C to +125°C guaranteed operating junction temperature - qualified for engine bay, infotainment, and ADAS subsystems without derating. |
Applications
| Automotive Battery Regulation | Industrial Control Power |
|---|---|
Use Scenario: Regulating 12V or 24V vehicle battery to stable 5V/3.3V rails for microcontrollers, sensors, and CAN transceivers in body electronics modules. IC Role / Device Role / Timing Role: Primary buck converter (VOUT1) and linear post-regulator controller (VOUT2) providing low-noise, tracked outputs with power-good signaling for ECU startup sequencing. Use Value: Eliminates need for discrete LDOs or second-stage converters; 36V max input withstands load-dump transients up to ISO 7637-2 Pulse 5a. | Use Scenario: Powering PLC I/O modules, motor drivers, and fieldbus interfaces from unregulated 24V industrial supplies subject to brownouts and surges. IC Role / Device Role / Timing Role: Main DC/DC regulator with programmable frequency (800kHz) to avoid noise coupling into analog signal chains and communication buses. Use Value: Adjustable switching frequency enables EMI filtering at fixed bands; 12μA shutdown current extends backup battery life during maintenance mode. |
| Wall Transformer Regulation | Distributed Power Regulation |
Use Scenario: Converting noisy, unregulated AC/DC adapter outputs (e.g., 9–24V) into clean 3.3V/1.8V for embedded networking devices and IoT gateways. IC Role / Device Role / Timing Role: High-efficiency step-down regulator with soft-start to prevent inrush into bulk capacitance and protect upstream rectifier stages. Use Value: 2.3A switch current and 250kHz–2.2MHz frequency range allow optimal tradeoff between transformer size, efficiency (>87% at 1MHz), and ripple performance. | Use Scenario: Generating local 5V and 3.3V rails from a shared 12V backplane in telecom line cards or server management controllers. IC Role / Device Role / Timing Role: Dual-output regulator with synchronized switching (via RT/SYNC) to minimize conducted EMI on shared power planes. Use Value: Synchronization capability prevents beat frequencies; complementary PG/PG outputs enable coordinated power-up of FPGA, PHY, and memory subsystems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output DC/DC regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | Monolithic 3A buck only (no linear regulator controller); 4V–15V input; 1.2MHz fixed frequency; MSE-16 package. | Suitable for higher-current single-rail applications but lacks LDRV/LFB tracking capability and wide 3V–36V input range. | Select when only high-current buck regulation is needed and input voltage is constrained to 4–15V. |
| TPS54202DDCR | 2A buck with integrated FETs; 4.5V–17V input; 2.5V–6V adjustable output; 2.5MHz max frequency; 6-pin SOT-23. | Smaller footprint and higher frequency, but no linear regulator function, no PG outputs, and narrower input range. | Select for space-constrained, single-output designs where 4.5–17V input and minimal BOM count are priorities. |
Compared with LTC3631EMSE#PBF and TPS54202DDCR, the LT3500IDD#TRPBF uniquely combines wide-input buck conversion with linear regulator control and true dual-feedback tracking in a thermally optimized DFN - making it the only option among the three qualified for automotive battery-fed dual-rail systems requiring –40°C to 125°C operation and 3V start-up.
Availability
LT3500IDD#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial control power, and wall transformer regulation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3500IDD#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial automation, and automotive markets.
The LT3500 product line was designed specifically for compact, high-reliability dual-output power conversion in harsh environments - integrating buck regulation, linear control, and system monitoring functions into a single IC to reduce solution size and improve thermal performance.
FAQ
What is the guaranteed operating temperature range for LT3500IDD#TRPBF?
The LT3500IDD#TRPBF is guaranteed to operate over a junction temperature range of –40°C to +125°C, with full electrical specifications validated across this range. This rating is explicitly confirmed in the "Order Information" table of the official datasheet and distinguishes it from the E-grade (0°C to 125°C) and H-grade (–40°C to 150°C) variants. The IDD suffix denotes Industrial grade with full –40°C to 125°C qualification.
Can LT3500IDD#TRPBF drive an external PNP transistor for higher linear regulator current?
Yes, the LT3500IDD#TRPBF's LDRV pin is explicitly designed to drive external pass transistors. As stated in the Pin Functions section, LDRV serves as the emitter of an internal NPN that "can be configured as an output of a linear regulator or as the drive for an external NPN high current regulator." While the internal LDRV delivers up to 13mA, connecting it to the base of an external PNP (with appropriate base resistor) enables high-current linear regulation - a documented configuration in the Applications Information section.
What is the minimum input voltage required for LT3500IDD#TRPBF to regulate a 3.3V output?
The LT3500IDD#TRPBF requires a minimum input voltage of approximately 4.06V to regulate a 3.3V output at 1A and 1MHz, calculated using DCMAX = 1 − tOFF(MIN) × f and VIN(MIN) = (VOUT + VD)/DCMAX − VD + VSW. This value assumes VD = 0.4V, VSW = 0.3V, and tOFF(MIN) = 110ns. The device's absolute minimum operating voltage is ~2.8V, but actual regulation depends on duty cycle limits and load conditions - detailed in the Applications Information section.
How does the LT3500IDD#TRPBF handle overload or short-circuit conditions?
The LT3500IDD#TRPBF employs multiple protection mechanisms: cycle-by-cycle current limiting disables the switch when sensed current exceeds the VC pin threshold; frequency foldback reduces switching frequency under overload to limit power dissipation; and thermal shutdown activates if junction temperature exceeds safe limits. These features are specified as functional across the full 3V–40V input range and are validated in the Absolute Maximum Ratings and Electrical Characteristics tables.
Is LT3500IDD#TRPBF pin-compatible with other LT3500 package variants?
No, the LT3500IDD#TRPBF (12-lead DFN) is not pin-compatible with the LT3500IMSE#TRPBF (16-lead MSE) variant. The DD package has 12 pins including SW, BST, LDRV, LFB, FB, PG, PG, VC, RT/SYNC, SHDN, SS, and VIN, while the MSE package adds NC pins and reassigns some functions - confirmed by comparing the TOP VIEW diagrams in the datasheet. Board layout must be specific to the DFN footprint.
LT3500IDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Topology:
- Step-Down (Buck) (1), Linear (LDO) (1)
- Number of Outputs:
- 2
- Frequency - Switching:
- 500kHz ~ 2.4MHz
- Voltage/Current - Output 1:
- 0.8V ~ 38.9V, 2A
- Voltage/Current - Output 2:
- Adjustable, 13mA
- Voltage/Current - Output 3:
- -
- w/LED Driver:
- No
- w/Supervisor:
- No
- w/Sequencer:
- No
- Voltage - Supply:
- 3V ~ 36V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-DFN (3x3)
LT3500IDD#TRPBF FAQ
1.How can I place an order for LT3500IDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3500IDD#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 LT3500IDD#TRPBF reliable?
The price and inventory of LT3500IDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3500IDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3500IDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3500IDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3500IDD#TRPBF?
LT3500IDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3500IDD#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 LT3500IDD#TRPBF?
For technical support, including LT3500IDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3500IDD#TRPBF requirements.
6.How does Aetrix verify that LT3500IDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3500IDD#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 LT3500IDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3500IDD#TRPBF?
All LT3500IDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3500IDD#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 LT3500IDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3500IDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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