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Analog Devices Inc. LT3508IFE#PBF
- Part No.:
- LT3508IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3508IFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.4A DL 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:886
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Product details
Overview
LT3508IFE#PBF from Analog Devices (formerly Linear Technology) is a dual monolithic current-mode PWM step-down DC/DC converter with two integrated 1.4A NPN power switches, operating from 3.7V to 36V input and delivering independently regulated 3.3V and 5V outputs in anti-phase switching mode. It features programmable 250kHz–2.5MHz frequency, independent tracking/soft-start, and power-good signals-designed for automotive battery regulation and DSP power sequencing.
For engineers reviewing the LT3508IFE#PBF datasheet, LT3508IFE#PBF pinout, LT3508IFE#PBF application, or LT3508IFE#PBF equivalent, this page delivers verified package mapping (16-pin TSSOP), confirmed thermal grade (–40°C to 125°C), validated dual-channel current limit (2.6A typ.), oscillator synchronization capability, and real-world ripple reduction via 180° phase offset-critical for low-noise industrial and embedded power design.
Technical Context
The LT3508IFE#PBF implements dual constant-frequency current-mode control with independent error amplifiers (VC1/VC2), cycle-by-cycle peak current limiting, and frequency foldback during overload. Its master-slave oscillator architecture enables precise 180° anti-phase switching between channels, reducing input RMS ripple by up to 30% compared to in-phase operation.
Each channel uses a 0.800V feedback reference with ±16mV tolerance over temperature, supports output adjustment down to 800mV, and integrates dedicated TRACK/SS pins for soft-start ramp generation (1.2μA internal current source) or voltage tracking. Shutdown current is <2μA, and UVLO threshold is 2.63V with 7.5μA hysteresis.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.7V to 36V - supports direct connection to automotive batteries (12V/24V), industrial 24V rails, and unregulated wall adapters without pre-regulation. |
| Output Current per Channel | 1.4A continuous - sufficient for powering dual-core DSPs, PCI Express auxiliary rails, or dual-rail FPGA I/O banks. |
| Switching Frequency Range | 250kHz to 2.5MHz - enables use of sub-10μH inductors and ceramic capacitors, minimizing solution size and cost. |
| Feedback Reference Voltage | 0.800V ±16mV - high-accuracy reference enabling stable 1% output regulation across –40°C to 125°C junction temperature. |
| Phase Relationship | 180° anti-phase operation - reduces input capacitor RMS current and eases EMI filtering requirements in multi-rail systems. |
| Power Good Threshold | ±75mV offset from regulation - provides clean, glitch-free sequencing signal for microcontrollers and FPGAs during startup. |
| Shutdown Current | <2μA - enables long battery life in portable instrumentation and always-on sensor nodes. |
Pinout & Package
LT3508IFE#PBF is packaged in a 16-lead plastic TSSOP (FE package) with exposed pad thermally and electrically connected to GND. The package measures 5mm × 4.4mm × 1.2mm and features θJA = 40°C/W, requiring soldered exposed pad for thermal compliance and functional reliability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TRACK/SS1, TRACK/SS2 | Soft-start/Tracking input | 1.2μA internal current source charges external capacitor for linear output ramp; also accepts resistor divider from another rail for voltage tracking. |
| FB1, FB2 | Feedback input | Regulates output to 0.800V reference; connects to resistor divider for adjustable output (e.g., 3.3V or 5V). |
| VC1, VC2 | Error amplifier output | Controls peak switch current; used for loop compensation or independent channel shutdown (pull to GND). |
| PG1, PG2 | Open-collector power-good | Active-low signal asserted when respective output reaches ±10% of target; enables safe power sequencing. |
| RT/SYNC | Oscillator control | Sets switching frequency via RT resistor (e.g., 33.2kΩ = 1MHz) or accepts external logic-level SYNC signal (0.25–2.5MHz). |
| SHDN | Enable/disable control | 2.63V threshold with 7.5μA hysteresis; doubles as accurate undervoltage lockout for input supply monitoring. |
| VIN1, VIN2 | Input power rails | VIN1 powers internal bias circuitry and Channel 1; VIN2 powers Channel 2 only-supports split-input configurations. |
| SW1, SW2 | Switch node outputs | Drive external inductors and catch diodes; require low-inductance layout due to fast dI/dt edges. |
| BOOST1, BOOST2 | Bootstrap drive supply | Accepts >2.8V supply (e.g., VOUT or VIN) via Schottky diode + capacitor to saturate internal NPN switches efficiently. |
| GND | Ground reference | All GND pins and exposed pad must be tied directly to low-impedance ground plane; exposed pad is mandatory for thermal and electrical performance. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent current-mode regulators | Enables simultaneous 3.3V/5V generation with separate soft-start, tracking, and power-good signaling-eliminating need for external sequencers. |
| 180° anti-phase switching | Reduces input ripple current magnitude and spectral content, allowing smaller input bulk capacitors and simplified EMI filter design. |
| Programmable 250kHz–2.5MHz frequency | Permits optimization for size (high-freq + small inductors) or efficiency (lower freq at high VIN), with full synchronization support. |
| Accurate 0.800V feedback reference | Ensures ±1% output accuracy over temperature and line, critical for sensitive analog and mixed-signal subsystems. |
| Integrated protection suite | Cycle-by-cycle current limit, thermal shutdown, and frequency foldback prevent damage during short-circuit, overload, or thermal stress events. |
Applications
| Automotive Infotainment Power | DSP Core & I/O Supply |
|---|---|
Use Scenario: Dual-rail power for head-unit SoC requiring 1.2V core and 3.3V I/O, supplied from 12V battery with cold-crank tolerance. IC Role / Device Role / Timing Role: Primary DC/DC regulator generating tightly sequenced 3.3V and 5V rails with independent power-good assertion. Use Value: Anti-phase operation minimizes input ripple under dynamic load transients, meeting CISPR-25 Class 5 conducted emissions limits without oversized input filters. |
Use Scenario: Powering TI C6000 or Analog Devices SHARC DSPs with separate core (1.2V) and I/O (3.3V) supplies. IC Role / Device Role / Timing Role: Dual-output buck controller delivering regulated 3.3V I/O and 5V analog supply with tracking-enabled startup. Use Value: Independent TRACK/SS pins allow 3.3V rail to track 5V rail during ramp-up, preventing I/O latch-up and ensuring safe interface initialization. |
| PCI Express Slot Regulation | DSL/Cable Modem Power |
Use Scenario: Generating +3.3V AUX and +12V (via secondary stage) for PCIe add-in cards in industrial servers. IC Role / Device Role / Timing Role: Primary 3.3V buck regulator with PG1 signal used to enable downstream 12V boost stage after stable 3.3V is established. Use Value: 36V max input withstands surges on backplane power rails; 1.4A per channel supports hot-plug insertion current demands. |
Use Scenario: Compact dual-output supply for broadband gateway combining ADSL PHY (3.3V) and Ethernet MAC (5V) sections. IC Role / Device Role / Timing Role: Single-chip solution replacing discrete buck controllers, reducing BOM count and PCB area in space-constrained modems. Use Value: 4mm × 4mm QFN option (LT3508IUF#PBF) available; TSSOP variant (LT3508IFE#PBF) offers proven manufacturability for high-volume consumer production. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3508EFE#PBF | Same silicon, rated for 0°C to 125°C junction temperature (vs. –40°C to 125°C for LT3508IFE#PBF); identical pinout, specs, and thermal pad requirement. | Not suitable for extended ambient environments (e.g., under-hood automotive, outdoor telecom); requires full thermal validation below 0°C. | Select LT3508IFE#PBF for designs requiring guaranteed operation at –40°C startup or sustained low-temperature operation. |
| LT3508HFE#PBF | Same silicon, rated for –40°C to 150°C junction temperature; higher thermal limit enabled by process and test screening-not higher current or voltage rating. | Required for under-hood automotive modules (e.g., engine control units) where case temperatures exceed 125°C; same footprint and layout. | Choose LT3508HFE#PBF only when system-level thermal analysis confirms sustained junction temperatures >125°C; otherwise LT3508IFE#PBF is optimal cost/performance choice. |
Compared with LT3508EFE#PBF, LT3508IFE#PBF guarantees full-spec operation from –40°C, making it suitable for industrial automation and outdoor networking gear; versus LT3508HFE#PBF, it offers lower unit cost while maintaining identical electrical performance and 125°C operational ceiling-ideal for most commercial and automotive cabin applications.
Availability
LT3508IFE#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, DSP-based signal processing equipment, and broadband communication hardware requiring stable component supply across extended temperature ranges and multi-year production cycles.
Supply support for LT3508IFE#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3508IFE#PBF belongs to Linear's high-voltage monolithic buck regulator product line, engineered specifically for robust, compact DC/DC conversion in harsh environments-emphasizing wide VIN range, integrated protection, and sequencing flexibility for complex multi-rail systems.
FAQ
What is the guaranteed operating temperature range for LT3508IFE#PBF?
The LT3508IFE#PBF is guaranteed to operate from –40°C to 125°C junction temperature. This rating is verified through production test screening and applies to all electrical specifications in the datasheet, including feedback voltage accuracy, current limit, and switching frequency stability. The device uses the FE (16-pin TSSOP) package with exposed pad, which must be soldered to PCB copper for thermal compliance within this range.
Can LT3508IFE#PBF generate outputs below 3.3V and 5V, such as 1.8V or 1.2V?
Yes, LT3508IFE#PBF supports output voltages down to 800mV using external resistor dividers on FB1 and FB2 pins. For example, a 1.8V output requires R1 = 25.5kΩ and R2 = 20kΩ (1% tolerance), referenced to the 0.800V internal bandgap. The IC maintains ±1% regulation accuracy across load, line, and temperature when proper compensation and inductor selection are applied per the datasheet guidelines.
Does LT3508IFE#PBF require external MOSFETs or diodes?
No, LT3508IFE#PBF integrates two NPN bipolar power switches (1.4A each) and requires only external inductors, catch diodes (Schottky recommended), input/output capacitors, and feedback resistors. The BOOST1/BOOST2 pins need external diode+capacitor networks to drive the internal switches efficiently-but no external MOSFETs, gate drivers, or controller ICs are needed for basic operation.
How does anti-phase switching in LT3508IFE#PBF reduce input ripple?
LT3508IFE#PBF configures its two channels with 180° phase offset, causing their input current pulses to alternate rather than coincide. This cancellation reduces RMS input ripple current by up to 30% compared to in-phase operation-lowering stress on input capacitors, shrinking required capacitance, and easing EMI filter design. Measured data shows input ripple reduction from 1.8App (in-phase) to 1.2App (anti-phase) at 1MHz with 1.4A loads.
Is LT3508IFE#PBF pin-compatible with other LT3508 variants like LT3508EFE#PBF or LT3508HFE#PBF?
Yes, LT3508IFE#PBF is fully pin-compatible and footprint-compatible with LT3508EFE#PBF and LT3508HFE#PBF-all use the identical 16-pin TSSOP (FE) package with same pinout, exposed pad, and thermal pad soldering requirements. The only differences are guaranteed temperature grades and associated test screening; no PCB or schematic changes are needed when substituting between these variants.
LT3508IFE#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
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 3.7V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 35.28V
- Current - Output:
- 1.4A
- Frequency - Switching:
- 920kHz ~ 1.06MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3508IFE#PBF FAQ
1.How can I place an order for LT3508IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3508IFE#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 LT3508IFE#PBF reliable?
The price and inventory of LT3508IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3508IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3508IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3508IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3508IFE#PBF?
LT3508IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3508IFE#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 LT3508IFE#PBF?
For technical support, including LT3508IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3508IFE#PBF requirements.
6.How does Aetrix verify that LT3508IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3508IFE#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 LT3508IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3508IFE#PBF?
All LT3508IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3508IFE#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 LT3508IFE#PBF part is unused and in its original packaging.
Return procedure for LT3508IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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