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Analog Devices Inc. LT3508IFE#TRPBF
- Part No.:
- LT3508IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3508IFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1.4A DL 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:13,452
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Product details
Overview
LT3508IFE#TRPBF 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/5V outputs in anti-phase mode. It features programmable 250kHz–2.5MHz switching frequency, independent tracking/soft-start, and power-good signals for sequencing-used in automotive infotainment power rails and industrial DSP supplies.
For engineers reviewing the LT3508IFE#TRPBF datasheet, LT3508IFE#TRPBF pinout, LT3508IFE#TRPBF application, or LT3508IFE#TRPBF equivalent, key selection criteria include its dual-channel 1.4A capability, 16-pin TSSOP thermal performance (θJA = 40°C/W), input UVLO threshold of 2.63V, and anti-phase ripple reduction-critical for low-noise multi-rail systems requiring tight supply sequencing and high VIN tolerance.
Technical Context
The LT3508IFE#TRPBF implements dual constant-frequency current-mode control with master-slave oscillator synchronization and 180° phase offset between channels, reducing input RMS ripple by canceling fundamental harmonics. Each channel uses an internal error amplifier (transconductance = 300μS, gain = 600V/V) driving VC pins to regulate peak switch current against a 0.800V FB reference.
It supports programmable frequency via RT/SYNC pin (7.5kΩ–169kΩ sets 2.5MHz–0.25MHz), includes cycle-by-cycle current limiting (2.6A typ at low duty cycle), frequency foldback under overload (down to 12% nominal), and thermal shutdown-enabling robust operation across –40°C to 125°C junction temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.7V to 36V - supports direct regulation from automotive batteries (12V/24V) and unregulated wall adapters without pre-regulation. |
| Output Current per Channel | 1.4A continuous - enables dual-core DSP or FPGA core/I/O rail generation with single-package solution. |
| Switching Frequency Range | 250kHz to 2.5MHz - allows trade-off between efficiency (lower f) and component size (higher f); 700kHz typical in 3.3V/5V applications. |
| Feedback Reference Voltage | 0.800V ±14mV - enables precise output setting down to 800mV using standard resistor dividers; line regulation <0.01%/V ensures stability across input range. |
| Power Good Threshold Accuracy | ±75mV offset - guarantees reliable sequencing with microcontrollers/DSPs by asserting PG when output reaches 90%–110% of target. |
| Shutdown Current | <2μA - supports battery-backed systems requiring ultra-low quiescent power during sleep modes. |
| Operating Junction Temperature | –40°C to +125°C - qualified for industrial and automotive under-hood environments with guaranteed performance over full range. |
Pinout & Package
LT3508IFE#TRPBF is packaged in a 16-lead plastic TSSOP (FE package) with exposed pad thermally and electrically connected to GND. The exposed pad must be soldered to PCB ground plane for thermal integrity (θJC = 10°C/W) and electrical stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TRACK/SS1, TRACK/SS2 | Soft-start & tracking input | Internal 1.2μA current source charges external capacitor for linear soft-start ramp; ties to another output's divider for voltage tracking-enables controlled power-up sequencing. |
| FB1, FB2 | Feedback input | Regulates output to 0.800V reference; connects to resistor divider tap-determines final output voltage with ±1.75% accuracy over temperature. |
| PG1, PG2 | Open-collector power-good output | Asserts low until output reaches 90% regulation; pulled high externally-provides sequenced enable signal for downstream logic or supervisor ICs. |
| RT/SYNC | Oscillator programming / sync input | Resistor-to-GND sets frequency (e.g., 33.2kΩ = 1MHz); accepts external logic-level clock up to 2.5MHz-enables EMI reduction via spread-spectrum sync. |
| SHDN | Enable/shutdown control | 2.63V threshold functions as accurate UVLO; pulls below 0.3V to enter <2μA shutdown-supports system-level power management. |
| VIN1, VIN2 | Input power supply pins | VIN1 powers internal bias circuitry and Channel 1 switch; VIN2 powers Channel 2 switch-allows independent sourcing or shared input with optimized layout. |
| SW1, SW2 | Switch node outputs | Drives external inductor/diode network; requires low-inductance routing to minimize EMI and voltage spikes during switching transitions. |
| BOOST1, BOOST2 | Bootstrap drive voltage | Tied via diode/capacitor to VOUT or VIN-generates >VIN voltage to saturate internal NPN switches, enabling high-efficiency operation at low duty cycles. |
| GND | Ground reference | Multiple GND pins and exposed pad form low-impedance return path-critical for noise immunity and thermal dissipation in high-current switching applications. |
| VC1, VC2 | Error amplifier output | Controls peak switch current; used for loop compensation or forced shutdown (pull to GND)-enables dynamic load transient response tuning. |
Key Features
| Feature | Design Value |
|---|---|
| Anti-phase switching | Reduces input ripple current magnitude by ~70% vs. in-phase operation-lowers required input capacitance and EMI filter complexity. |
| Independent tracking & soft-start | Enables precise sequencing of dual outputs (e.g., core before I/O) without external controllers-simplifies BOM and board space in multi-rail systems. |
| Programmable undervoltage lockout | 2.63V SHDN threshold with 7.5μA hysteresis-prevents erratic startup during brown-out conditions and ensures clean power-on reset behavior. |
| Small inductor/ceramic capacitor support | High-frequency operation (up to 2.5MHz) permits use of 4.7μH/6.8μH shielded inductors and X7R ceramic caps-reduces solution footprint by >40% vs. 500kHz designs. |
| Thermal shutdown & current limit | Protects against short-circuit, overtemperature (>150°C), and overload-maintains reliability in harsh environments without external protection circuitry. |
Applications
| Automotive Infotainment Power | DSP Core & I/O Supply |
|---|---|
Use Scenario: Dual-rail power for head-unit SoC requiring 3.3V I/O and 1.2V core (via external LDO), with strict sequencing and low EMI in crowded dashboard environment. IC Role / Device Role: Primary DC/DC regulator generating stable 3.3V/5V rails; PG signals coordinate LDO enable timing and processor reset assertion. Use Value: Anti-phase operation cuts input ripple, easing compliance with CISPR-25 Class 5 emissions limits; wide 3.7V–36V input handles cold-crank (6.5V) and load-dump (40V) transients. |
Use Scenario: Powering TI C6000 or Analog Devices SHARC DSPs with separate 1.2V core and 3.3V interface supplies in test equipment. IC Role / Device Role: Dual-channel buck controller delivering 1.4A each; TRACK/SS pins enforce 3.3V rail rise before 1.2V rail to prevent latch-up. Use Value: Independent soft-start eliminates inrush current surges that could trip upstream 5V bus fuses; 125°C rating supports convection-cooled enclosures. |
| PCI Express Slot Power | DSL/Cable Modem Power |
Use Scenario: Generating +3.3V AUX and +12V (via external boost) for PCIe add-in cards in industrial servers where space and thermal density are constrained. IC Role / Device Role: Primary 3.3V rail generator; second channel supplies auxiliary logic or fan controller; PG1 triggers hot-plug detection handshake. Use Value: 16-pin TSSOP fits narrow PCIe card edge; 36V max input accommodates legacy 24V backplane supplies with margin for ripple. |
Use Scenario: Compact AC/DC adapter replacement in residential DSL modems requiring isolated 5V/3.3V rails from unregulated 12V–24V input. IC Role / Device Role: Main DC/DC stage converting wall-adapter output; RT/SYNC pin synchronized to system clock to suppress beat frequencies. Use Value: 2.5MHz max frequency enables <3mm × 3mm inductor footprint-critical for ultra-thin modem housings; <2μA shutdown extends standby battery life. |
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 |
|---|---|---|---|
| LM5143AQPWPRQ1 | 42V input, dual 3A channels, synchronous FETs, 500kHz–2.2MHz; no internal NPN switches-requires external MOSFETs. | Higher current, automotive AEC-Q100 Grade 1; lacks integrated tracking/soft-start-needs external sequencing IC. | Choose for >1.4A loads or where synchronous rectification improves efficiency >90%; avoid if board space or BOM count is critical. |
| TPS54290PWPR | 36V input, dual 2A channels, integrated MOSFETs, 100kHz–1.5MHz; no anti-phase operation-higher input ripple. | Lower cost, commercial temp only (–40°C to 85°C); no PG outputs-requires external monitoring. | Choose for cost-sensitive industrial applications without automotive/sequencing requirements; verify thermal derating above 85°C ambient. |
Compared with LM5143AQPWPRQ1 and TPS54290PWPR, the LT3508IFE#TRPBF delivers unique integration of anti-phase ripple cancellation, dual independent PG outputs, and seamless tracking/soft-start-all in a compact 16-pin TSSOP-making it optimal for space-constrained, multi-rail systems demanding precise sequencing and low EMI.
Availability
LT3508IFE#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial DSP power, PCI Express slot supplies, and DSL/cable modem designs requiring stable component supply across extended temperature and high-reliability production cycles.
Supply support for LT3508IFE#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, serving precision instrumentation, industrial automation, and automotive markets.
The LT3508IFE#TRPBF belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for rugged multi-rail power conversion in automotive, industrial, and telecom infrastructure where wide input range, sequencing, and thermal resilience are mandatory.
FAQ
What is the maximum input voltage rating for LT3508IFE#TRPBF?
The LT3508IFE#TRPBF has an absolute maximum VIN pin voltage of 40V, but its functional maximum operating input is 36V as specified in the Electrical Characteristics table. Operation above 36V risks pulse-skipping instability and increased peak inductor current; for reliable regulation, input must stay ≤36V with adequate margin for ripple and transients. The LT3508IFE#TRPBF datasheet confirms this limit applies across its full –40°C to 125°C operating junction temperature range.
Does LT3508IFE#TRPBF support independent output voltage adjustment?
Yes, LT3508IFE#TRPBF supports fully independent output voltage adjustment via separate FB1 and FB2 pins, each regulated to a precise 0.800V reference. Users set VOUT1 and VOUT2 using individual resistor dividers-e.g., 3.3V on Channel 1 (R1=30.1kΩ, R2=10kΩ) and 5V on Channel 2 (R1=51.1kΩ, R2=10kΩ). The LT3508IFE#TRPBF maintains ±1.75% output accuracy over temperature and line, with no coupling between channels unless TRACK/SS pins are intentionally connected.
How does the anti-phase switching in LT3508IFE#TRPBF reduce input ripple?
The LT3508IFE#TRPBF internally generates 180° out-of-phase clock signals for its two channels, causing input current pulses to alternate rather than coincide. This cancels the fundamental ripple component, reducing RMS input ripple current by up to 70% compared to in-phase operation. As confirmed in the Typical Application schematic (TA01a), this allows smaller input capacitors (e.g., 10μF ceramic) and simpler EMI filtering-directly validated by LT3508IFE#TRPBF efficiency plots showing stable performance at 700kHz with minimal input voltage sag.
What thermal considerations apply to LT3508IFE#TRPBF in 16-pin TSSOP package?
The LT3508IFE#TRPBF in 16-pin TSSOP (FE package) has θJA = 40°C/W and θJC = 10°C/W, requiring the exposed pad to be soldered to a minimum 100mm² copper pour for effective heat transfer. At 1.4A per channel and 12V input, junction temperature rise is ~42°C above ambient-well within its 125°C max rating. The LT3508IFE#TRPBF integrates thermal shutdown that activates >150°C, protecting against sustained overload; derating is recommended above 85°C ambient.
Can LT3508IFE#TRPBF be synchronized to an external clock?
Yes, LT3508IFE#TRPBF supports external synchronization via its RT/SYNC pin: applying a logic-level square wave (≥80ns pulse width, 0.25MHz–2.5MHz) overrides the internal oscillator and locks both channels to the external frequency. This feature is explicitly documented in the Pin Functions section and enables EMI reduction by aligning switching edges with system clocks-verified in the Synchronization subsection of the Applications Information, where LT3508IFE#TRPBF maintains stable regulation and anti-phase operation under sync.
LT3508IFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3508IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3508IFE#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 LT3508IFE#TRPBF reliable?
The price and inventory of LT3508IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3508IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3508IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3508IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3508IFE#TRPBF?
LT3508IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3508IFE#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 LT3508IFE#TRPBF?
For technical support, including LT3508IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3508IFE#TRPBF requirements.
6.How does Aetrix verify that LT3508IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3508IFE#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 LT3508IFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3508IFE#TRPBF?
All LT3508IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3508IFE#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 LT3508IFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3508IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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