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Analog Devices Inc. LT3500HDD#TRPBF
- Part No.:
- LT3500HDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Regulators - Linear + Switching
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LT3500HDD#TRPBF.pdf
- Description:
- IC REG DL BUCK/LINEAR 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,871
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Product details
Overview
LT3500HDD#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 40V input and delivering adjustable output down to 0.8V. It features 250kHz–2.2MHz resistor-programmable switching frequency, soft-start/tracking capability, and power-good comparator with complementary outputs - used in automotive battery regulation and industrial control systems requiring dual-output power management.
For engineers reviewing the LT3500HDD#TRPBF datasheet, LT3500HDD#TRPBF pinout, LT3500HDD#TRPBF application, or LT3500HDD#TRPBF equivalent, key selection criteria include its –40°C to 150°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 synchronized dual-output regulation.
Technical Context
The LT3500HDD#TRPBF implements constant-frequency current-mode PWM control with cycle-by-cycle current limiting, frequency foldback, and thermal shutdown. Its dual-loop architecture includes a main buck converter (FB pin, 0.8V reference) and an independent linear regulator path (LFB/LDRV pins, also 0.8V reference), both sharing soft-start ramping via the SS pin.
It supports resistor-programmed or external-synchronized operation (250kHz–2.2MHz), uses BST-driven NPN switch topology requiring external boost capacitor and catch diode, and integrates a power-good comparator with 30mV hysteresis that monitors both FB and LFB simultaneously against 90% of nominal reference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 40V max; supports automotive batteries (12V/24V), industrial 24V supplies, and unregulated wall adapters. |
| Switch Peak Current | 2.3A typical (DD package); enables 2A continuous output with margin for transient loads. |
| Feedback Reference | 0.8V ±1.2% over full –40°C to 150°C range; ensures stable output regulation across extended temperature. |
| Shutdown Current | <12μA typical; enables low-power battery management without external disconnect circuitry. |
| Switching Frequency | 250kHz to 2.2MHz; adjustable via RT/SYNC resistor or external sync signal for EMI control and size optimization. |
| Linear Regulator Drive | LDRV pin delivers up to 13mA; configurable as linear regulator output or external NPN driver for higher-current linear stages. |
| Power Good Output | Open-collector PG/PG with 30mV hysteresis; asserts when both FB and LFB exceed 90% of 0.8V reference. |
Pinout & Package
LT3500HDD#TRPBF is housed in a thermally enhanced 12-lead (3mm × 3mm) plastic DFN package 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 |
|---|---|---|
| SW | Switch Emitter | Emitter of internal 2.3A NPN power switch; connects to inductor and external catch diode cathode. |
| BST | Boost Supply | Provides >VIN base drive to internal NPN; requires external capacitor between BST and SW for saturation. |
| LDRV | Linear Driver Output | Emitter of internal NPN linear stage; delivers up to 13mA for local LDO or external high-current linear regulator drive. |
| LFB | Linear Feedback Input | Negative input to linear error amplifier; regulated to 0.8V by LDRV output for precise linear output control. |
| FB | Switcher Feedback Input | Negative input to buck error amplifier; regulated to 0.8V by SW output for main DC/DC output control. |
| PG / PG | Power Good Outputs | Complementary open-collector outputs indicating regulation status of both FB and LFB paths. |
| VIN | Main Power Input | Powers internal bias circuits and collector of both internal NPN switches; must be decoupled locally. |
| SHDN | Shutdown Control | Active-high enable with 760mV threshold; places device in 12μA shutdown mode when pulled low. |
| SS | Soft-Start/Tracking | Controls ramp rate of both buck and linear outputs via external capacitor; enables output voltage tracking. |
| VC | Error Amplifier Output | Transconductance amplifier output; used for loop compensation, current limiting, or override control. |
| RT/SYNC | Frequency Set/Sync Input | Accepts resistor-to-ground for frequency setting (250kHz–2.2MHz) or external clock for synchronization. |
| GND (Exposed Pad) | Ground Reference | Only ground connection; must be soldered to large copper area for thermal and noise performance. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-output regulation architecture | Independent buck (FB) and linear (LFB/LDRV) control loops share soft-start ramp and shutdown logic for coordinated power sequencing. |
| Thermally robust packaging | 12-lead 3mm × 3mm DFN with exposed GND pad rated for –40°C to 150°C junction temperature - validated for under-hood automotive use. |
| Programmable frequency with sync | 250kHz–2.2MHz adjustment via single RT/SYNC resistor or external clock input, enabling EMI spread-spectrum design and multi-rail synchronization. |
| Integrated protection suite | Cycle-by-cycle current limit, frequency foldback during overload, thermal shutdown, and VIN undervoltage lockout prevent fault propagation. |
| Tracking soft-start | Single SS capacitor controls ramp rate of both switching and linear outputs, enabling precise voltage sequencing in multi-rail systems. |
Applications
| Automotive Battery Regulation | Industrial Control Systems |
|---|---|
Use Scenario: Regulating 12V or 24V vehicle battery supply to generate stable 5V and 3.3V rails for infotainment ECUs and ADAS sensors. IC Role / Device Role / Timing Role: Dual-output power manager providing primary buck conversion and auxiliary linear regulation with coordinated soft-start and power-good signaling. Use Value: Guaranteed operation up to 150°C junction temperature eliminates need for derating or external thermal management in engine bay environments. | Use Scenario: Powering PLC I/O modules and fieldbus interfaces from unregulated 24V industrial supplies subject to line transients and wide temperature swings. IC Role / Device Role / Timing Role: High-input-voltage step-down regulator with short-circuit protection across full 3V–40V range and programmable frequency for noise-sensitive analog sections. Use Value: 40V absolute maximum VIN rating and cycle-by-cycle current limiting ensure reliable operation during 48V surge events on 24V bus lines. |
| Wall Transformer Regulation | Distributed Power Regulation |
Use Scenario: Converting noisy, unregulated AC/DC wall adapter output into clean 5V/3.3V for embedded microcontrollers and peripherals in consumer IoT gateways. IC Role / Device Role / Timing Role: Monolithic buck + linear regulator replacing discrete solutions; reduces BOM count while maintaining low-noise linear output for sensitive RF sections. Use Value: Integrated LDRV stage delivers 13mA low-noise linear output without external pass transistor, minimizing footprint and layout complexity. | Use Scenario: Generating multiple isolated or semi-isolated rails in telecom line cards where space-constrained board area demands high integration density. IC Role / Device Role / Timing Role: Compact dual-output DC/DC solution enabling compact point-of-load designs with minimal external components (inductor, diode, capacitors). Use Value: 2.2MHz max switching frequency allows use of sub-2.2μH inductors and 10μF ceramic output caps, reducing total solution size by >40% vs 500kHz alternatives. |
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 integrated linear regulator); 4V–15V input; 3mm × 4mm MSE package. | Lacks LDRV/LFB functionality - requires external linear stage for dual-output tracking; lower input voltage ceiling. | Select when higher 3A buck current is required and linear rail can be implemented externally. |
| TPS54202DDCR | 2A buck-only converter; 4.5V–28V input; 6-pin SOT-23; no linear regulator, no PG outputs, no sync capability. | No linear regulator path, no power-good signaling, no temperature grade beyond 125°C - unsuitable for automotive or high-reliability industrial use. | Select only for cost-sensitive, single-rail, commercial-temperature applications with tight board space constraints. |
Compared with LTC3631EMSE#PBF and TPS54202DDCR, the LT3500HDD#TRPBF uniquely integrates both a 2A buck converter and a 13mA linear regulator controller in one die, supports 3V–40V input with 150°C operation, and provides dual PG outputs - making it the only option among the three qualified for automotive under-hood and high-temperature industrial dual-rail power management.
Availability
LT3500HDD#TRPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial control systems, and distributed power regulation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3500HDD#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 high-reliability dual-output power management in harsh environments - combining a robust buck converter with a linear regulator controller to simplify multi-rail designs in automotive, industrial, and telecom infrastructure.
FAQ
What is the guaranteed operating temperature range for LT3500HDD#TRPBF?
The LT3500HDD#TRPBF is guaranteed to operate over a junction temperature range of –40°C to 150°C. This specification is explicitly validated and tested per manufacturer data sheet Note 2, distinguishing it from E-grade (–40°C to 125°C) and I-grade variants. The H-grade qualification makes LT3500HDD#TRPBF suitable for under-hood automotive and high-ambient industrial applications where thermal derating is critical.
Does LT3500HDD#TRPBF support synchronization to an external clock?
Yes, LT3500HDD#TRPBF supports external clock synchronization via the RT/SYNC pin. When an external clock signal is applied, synchronization occurs on the rising edge, and the internal oscillator automatically adjusts slope compensation to prevent subharmonic oscillation. The device accepts sync frequencies from 250kHz to 2500kHz and reverts to resistor-programmed mode if the external clock is removed - ensuring seamless fallback behavior without system interruption.
How does the LT3500HDD#TRPBF implement dual-output regulation?
The LT3500HDD#TRPBF implements dual-output regulation using two independent feedback paths: the FB pin controls the main buck converter output (0.8V reference), while the LFB pin controls the linear regulator path (also 0.8V reference) driven by the LDRV pin. Both loops share the same soft-start ramp (SS pin), shutdown control (SHDN), and power-good monitoring (PG/PG), enabling coordinated startup, sequencing, and fault response across both outputs without external timing components.
What is the role of the BST pin on LT3500HDD#TRPBF?
The BST pin on LT3500HDD#TRPBF provides boosted base drive to the internal NPN power switch, ensuring low saturation voltage (<450mV at 2A). It requires an external capacitor connected between BST and SW to generate a voltage ~1.5V–2V above VIN. A comparator monitors BST voltage relative to SW and enforces minimum off-time if BST drops too low - allowing the boost capacitor time to recharge and maintaining switch saturation across input voltage and load variations.
Can LT3500HDD#TRPBF drive an external PNP or NPN transistor for higher linear output current?
Yes, LT3500HDD#TRPBF's LDRV pin is explicitly designed to drive external pass transistors. As stated in the datasheet Pin Functions section, LDRV "can be configured as an output of a linear regulator or as the drive for an external NPN high current regulator." With 13mA drive capability and 0.8V LFB reference, it supports configurations such as emitter-follower NPN or PNP-based linear regulators - extending the linear output current beyond the internal 13mA limit while retaining regulation accuracy and tracking.
LT3500HDD#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 ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-DFN (3x3)
LT3500HDD#TRPBF FAQ
1.How can I place an order for LT3500HDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3500HDD#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 LT3500HDD#TRPBF reliable?
The price and inventory of LT3500HDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3500HDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3500HDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3500HDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3500HDD#TRPBF?
LT3500HDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3500HDD#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 LT3500HDD#TRPBF?
For technical support, including LT3500HDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3500HDD#TRPBF requirements.
6.How does Aetrix verify that LT3500HDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3500HDD#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 LT3500HDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3500HDD#TRPBF?
All LT3500HDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3500HDD#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 LT3500HDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3500HDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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