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Analog Devices Inc. LT3508EFE#TRPBF
- Part No.:
- LT3508EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3508EFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1.4A DL 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:8,737
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Product details
Overview
LT3508EFE#TRPBF from Analog Devices (formerly Linear Technology) is a dual monolithic current-mode PWM step-down DC/DC converter with integrated 1.4A NPN power switches per channel, operating from 3.7V to 36V input and delivering two independent regulated outputs. It features programmable 250kHz–2.5MHz switching frequency, anti-phase operation to reduce input ripple, and independent tracking/soft-start/power-good circuits for precise supply sequencing in multi-rail systems.
For engineers reviewing the LT3508EFE#TRPBF datasheet, LT3508EFE#TRPBF pinout, LT3508EFE#TRPBF application, or LT3508EFE#TRPBF equivalent, this device is selected for automotive infotainment power rails, DSP core/I/O supplies, PCI Express auxiliary power, and industrial 24V-to-3.3V/5V dual-output conversion where input ripple suppression, thermal robustness (–40°C to 125°C), and board-space-constrained designs are critical.
Technical Context
The LT3508EFE#TRPBF implements dual constant-frequency current-mode control with independent error amplifiers (VC1/VC2), cycle-by-cycle current limiting, and frequency foldback under overload. Its master-slave oscillator architecture enables synchronized anti-phase switching across both channels using a single RT/SYNC pin.
Each channel uses an internal 0.800V reference with ±16mV tolerance over temperature, supports output adjustment down to 800mV via resistor divider feedback (FB1/FB2), and integrates undervoltage lockout (UVLO) with 3.7V threshold on VIN1 and 3.0V on VIN2. The exposed-pad 16-pin TSSOP package provides θJA = 40°C/W thermal resistance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.7V to 36V - supports direct regulation from automotive batteries, 24V industrial rails, and unregulated wall adapters without pre-regulation. |
| Output Current per Channel | 1.4A continuous - enables dual high-current rails (e.g., 3.3V/1.4A + 5V/1.4A) from a single IC, reducing component count vs. discrete solutions. |
| Switching Frequency | 250kHz to 2.5MHz - allows selection of small inductors (e.g., 6.8μH at 700kHz) and ceramic capacitors while balancing efficiency vs. EMI. |
| Feedback Reference Voltage | 0.800V ±16mV (–40°C to 125°C) - ensures tight output regulation accuracy across automotive and industrial temperature ranges. |
| Shutdown Current | <2μA - enables ultra-low-power state management in battery-backed systems without external load switches. |
| Power Good Threshold | ±75mV offset from regulation - provides reliable sequencing signal for microcontrollers/DSPs when output reaches 90–110% of target voltage. |
| Operating Junction Temp | –40°C to 125°C - qualified for extended-temperature automotive and industrial applications without derating. |
Pinout & Package
LT3508EFE#TRPBF is housed in a 16-lead plastic TSSOP package with exposed thermal pad (Pin 17), requiring soldering to PCB ground for thermal and electrical integrity. Package dimensions: 5mm × 4.4mm × 1.2mm.
| 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 during power-up. |
| FB1, FB2 | Feedback input | Regulates output to 0.800V reference; connects to resistor divider tap - sets output voltage as VOUT = 0.8V × (1 + R1/R2). |
| PG1, PG2 | Open-collector power-good output | Drives low until respective output reaches ±10% of target; used for supply sequencing or system reset assertion. |
| RT/SYNC | Oscillator control | Resistor-to-GND sets frequency (e.g., 33.2kΩ = 1MHz); accepts external logic-level SYNC signal for system-wide clock alignment. |
| SHDN | Enable/disable control | 2.63V threshold enables UVLO function; pulling below 0.3V disables both regulators and reduces quiescent current to <2μA. |
| VIN1, VIN2 | Input power rails | VIN1 powers internal bias circuitry and Channel 1 switch; VIN2 powers Channel 2 switch - supports split-input configurations. |
| SW1, SW2 | Switch node outputs | Drive external inductor/catch diode/boost capacitor; bipolar NPN switches rated for 1.4A continuous, 3.2A peak current limit. |
| BOOST1, BOOST2 | Bootstrap drive supply | Accepts >VIN+2.5V supply (e.g., from VOUT) to saturate internal NPN switches - improves efficiency at high duty cycles. |
| VC1, VC2 | Error amplifier output | Controls peak switch current; used for loop compensation or external override (e.g., pull to GND to disable channel). |
| GND | Ground reference | All GND pins and exposed pad must connect to low-impedance PCB ground plane - critical for noise immunity and thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| Anti-phase switching | Reduces RMS input ripple current by up to 70% vs. in-phase operation - lowers required input capacitance and EMI filter size. |
| Independent soft-start & tracking | Enables controlled power-up sequencing (e.g., I/O rail before core rail) without external timers or supervisors - simplifies BOM. |
| Programmable UVLO | SHDN pin doubles as accurate undervoltage lockout (3.7V on VIN1) - prevents erratic startup during brownout conditions. |
| Thermal shutdown & foldback | Protects against short-circuit faults by reducing switching frequency to 12% of nominal value when VFB < 0.625V - limits peak switch current and junction temperature. |
| Small-solution footprint | Supports 4.7μF input / 22μF output ceramic caps and 6.8μH inductors at 700kHz - achieves full 1.4A dual-output design in <1 cm² PCB area. |
Applications
| Automotive Infotainment Power | DSP Core & I/O Supply |
|---|---|
Use Scenario: Powering head-unit MCU (3.3V), display interface (5V), and audio codec (1.8V) from 12V battery with cold-crank tolerance. IC Role / Device Role / Timing Role: Dual-output buck regulator providing sequenced, ripple-reduced rails with PG signaling for safe processor boot. Use Value: Anti-phase operation cuts input ripple by 65%, enabling smaller input caps; –40°C to 125°C rating ensures reliability across engine bay temperatures. |
Use Scenario: Generating separate 1.2V core and 3.3V I/O supplies for TI C6000 DSPs in test equipment. IC Role / Device Role / Timing Role: Dual-channel regulator with independent TRACK/SS pins enabling I/O rail to track core rail during dynamic voltage scaling. Use Value: Independent soft-start prevents inrush current conflicts; 0.800V reference ensures ±1.5% output accuracy over temperature for stable DSP operation. |
| PCI Express Auxiliary Power | DSL/Cable Modem Power |
Use Scenario: Delivering +3.3V AUX and +12V (via external LDO) from 12V rail in PCIe add-in cards with strict inrush limits. IC Role / Device Role / Timing Role: Primary buck controller generating 3.3V AUX rail; PG1 signals slot controller when rail is stable per PCIe spec. Use Value: <2μA shutdown current meets PCIe standby power requirements; 36V max input accommodates 12V supply tolerances and transients. |
Use Scenario: Powering ADSL line driver (5V) and PHY (3.3V) from 24V PoE-powered DSLAM shelf. IC Role / Device Role / Timing Role: Dual buck regulator converting 24V to isolated 5V/3.3V rails with independent enable control for modular power management. Use Value: Wide 3.7–36V input range eliminates need for pre-regulator; TSSOP package fits dense modem PCB layouts with minimal thermal vias. |
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, 3A/channel, synchronous FETs, spread-spectrum EMI reduction - no internal NPN switches; requires external MOSFETs. | Targeted at automotive ADAS with AEC-Q100 Grade 1; lacks independent TRACK/SS pins - limited sequencing flexibility. | Select for higher current (>1.4A) or lower conduction loss; avoid if board space or BOM simplicity is prioritized over efficiency. |
| TPS54290PWPR | 36V input, 2A/channel, integrated FETs, 100kHz–2.2MHz frequency - fixed 0.8V reference, no programmable UVLO on EN pin. | Designed for telecom/datacom; no anti-phase operation - higher input ripple requires larger bulk capacitance. | Select for cost-sensitive industrial apps needing 2A output; avoid when input ripple reduction or precise sequencing is required. |
Compared with LM5143AQPWPRQ1 and TPS54290PWPR, the LT3508EFE#TRPBF delivers superior supply sequencing control via independent TRACK/SS and PG pins, lower solution size due to integrated bipolar switches, and tighter input ripple suppression through inherent anti-phase operation - making it optimal for space-constrained, multi-rail embedded systems.
Availability
LT3508EFE#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment, DSP power supplies, and DSL/cable modem designs requiring stable component supply, long-term lifecycle support, and guaranteed extended-temperature performance.
Supply support for LT3508EFE#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 automotive, industrial, communications, and healthcare markets.
The LT3508EFE#TRPBF belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for compact, efficient dual-rail power conversion in harsh environments where wide input range, thermal resilience, and sequencing control are essential.
FAQ
What is the maximum input voltage rating for the LT3508EFE#TRPBF?
The LT3508EFE#TRPBF has an absolute maximum VIN pin voltage of 40V, but its functional maximum operating voltage is 36V as specified in the Electrical Characteristics table. Operation above 36V risks violating the minimum duty cycle limit and may induce pulse-skipping behavior - sustained operation beyond 36V is not recommended even if within absolute ratings.
Can the LT3508EFE#TRPBF generate outputs below 3.3V, such as 1.8V or 1.2V?
Yes, the LT3508EFE#TRPBF supports output voltages down to 800mV using the FB1/FB2 pins and external resistor dividers. For a 1.8V output, use R1 = R2 × (1.8V/0.8V − 1); R2 ≤ 20kΩ is recommended to minimize bias current error. The 0.800V reference is guaranteed over –40°C to 125°C, ensuring stability across temperature.
Does the LT3508EFE#TRPBF require external catch diodes?
No, the LT3508EFE#TRPBF integrates bipolar NPN power switches and does not require external catch diodes. However, external Schottky diodes are needed between SWx and BOOSTx pins to generate the bootstrap voltage for switch saturation - standard practice for bipolar-based buck controllers to maintain high efficiency at high duty cycles.
How does anti-phase switching reduce input ripple in the LT3508EFE#TRPBF?
The LT3508EFE#TRPBF configures its two channels to switch 180° out-of-phase using a shared oscillator. This causes their input current pulses to partially cancel at the VIN node, reducing RMS input ripple current by up to 70% compared to in-phase operation - directly lowering required input capacitance and EMI filter complexity.
What is the purpose of the exposed thermal pad on the LT3508EFE#TRPBF TSSOP package?
The exposed pad (Pin 17) on the LT3508EFE#TRPBF serves as both the primary thermal path to the PCB and the electrical ground connection. It must be soldered to a thermally robust ground plane with ≥4 thermal vias to achieve the specified θJA = 40°C/W and prevent junction temperature exceedance under 1.4A load conditions.
LT3508EFE#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
LT3508EFE#TRPBF FAQ
1.How can I place an order for LT3508EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3508EFE#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 LT3508EFE#TRPBF reliable?
The price and inventory of LT3508EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3508EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3508EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3508EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3508EFE#TRPBF?
LT3508EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3508EFE#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 LT3508EFE#TRPBF?
For technical support, including LT3508EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3508EFE#TRPBF requirements.
6.How does Aetrix verify that LT3508EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3508EFE#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 LT3508EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3508EFE#TRPBF?
All LT3508EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3508EFE#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 LT3508EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3508EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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