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Analog Devices Inc. LT3501IFE#PBF
- Part No.:
- LT3501IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3501IFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 3A DL 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:341
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Product details
Overview
LT3501IFE#PBF from Analog Devices (formerly Linear Technology) is a monolithic dual-current-mode PWM step-down DC/DC converter with two internal 3.5A NPN power switches, independent input supplies (VIN1/VIN2), feedback (FB1/FB2), soft-start (SS/TRACK1/SS/TRACK2), and power-good (PG1/PG2) pins. It delivers up to 3A per channel across 3.1V–25V input, supports 250kHz–1.5MHz programmable/synchronizable switching, and maintains 180° antiphase operation for ripple reduction - used in DSP power supplies and DSL/cable modem rails.
For engineers reviewing the LT3501IFE#PBF datasheet, LT3501IFE#PBF pinout, LT3501IFE#PBF application, or LT3501IFE#PBF equivalent, key selection criteria include dual-channel tracking capability, 95% max duty cycle dropout performance, independent shutdown control via SHDN, thermal robustness (–40°C to 125°C), and TSSOP-20 exposed-pad package compatibility with high-current PCB layouts.
Technical Context
The LT3501IFE#PBF implements current-mode control per channel using an internal transconductance error amplifier (gm = 150–450 µmho), peak current sensing via IND/VOUT pins, and slope-compensated oscillator synchronized to external clock or RT/SYNC resistor. Each channel features independent VC pin-based current limiting and soft-start ramping driven by 3.25µA source current.
Its architecture enables ratiometric, sequential, or absolute output voltage tracking; antiphase switching reduces input capacitor RMS current; and BST1/BST2 boost capacitors enable high-efficiency saturation of internal NPN switches - critical for maintaining <600mV switch saturation voltage at 3A load and supporting >95% duty cycle in dropout conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.1V to 25V - supports wide-range industrial and telecom inputs without pre-regulation. |
| Output Current per Channel | 3A continuous - enabled by internal 3.5A NPN switches and exposed-pad TSSOP thermal design. |
| Switching Frequency Range | 250kHz to 1.5MHz - set via RT/SYNC resistor or external clock; allows optimization of size vs. efficiency. |
| Feedback Reference Voltage | 0.8V ±2% - precise regulation point enabling accurate 1.8V, 3.3V, and 5V outputs with standard resistor dividers. |
| Max Duty Cycle | ~95% - achieved via boost capacitor recharge management, enabling low-VIN–VOUT operation (e.g., 3.3V out from 3.6V input). |
| Operating Junction Temp | –40°C to 125°C - fully specified and tested over full range (IFE grade), suitable for automotive under-hood and industrial environments. |
| Shutdown Quiescent Current | <10µA - ensures ultra-low system standby power when SHDN is asserted. |
Pinout & Package
The LT3501IFE#PBF is housed in a 20-lead plastic TSSOP package with exposed leadframe (pin 21 = GND), optimized for low θJA = 45°C/W and θJC(PAD) = 10°C/W. The exposed pad must be soldered to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN1 (1) | Channel 1 input supply & bias rail | Powers internal circuitry and connects to collector of Ch1 NPN switch; requires local high-dI/dt decoupling. |
| SW1 (2) | Channel 1 switch emitter | Drives external inductor; requires Schottky catch diode to prevent negative voltage excursions during flyback. |
| IND1 (3) | Channel 1 current sense input | Connects to inductor side of internal sense resistor; monitors peak inductor current for cycle-by-cycle control. |
| VOUT1 (4) | Channel 1 current sense return | Completes current-sense path; bias current flows out if VOUT1 < 1.6V - used for current limit detection. |
| PG1 (5) | Channel 1 power-good open-collector | Sinks current when FB1 falls below 90% of 0.8V; indicates regulated output status with 30mV hysteresis. |
| PG2 (6) | Channel 2 power-good open-collector | Independent PG signal for Ch2; can be tied to PG1 for combined monitoring or left floating. |
| VOUT2 (7) | Channel 2 current sense return | Same function as VOUT1 but for Ch2; enables independent current sensing and overload protection. |
| IND2 (8) | Channel 2 current sense input | Same function as IND1 but for Ch2; supports independent current-mode regulation per channel. |
| SW2 (9) | Channel 2 switch emitter | 180° antiphase with SW1; reduces input ripple and eases EMI filtering requirements. |
| VIN2 (10) | Channel 2 input supply | Independent collector supply for Ch2 NPN; may tie to VIN1 or use separate rail for sequencing flexibility. |
| BST1 (20) | Channel 1 bootstrap drive | Provides >VIN base drive to Ch1 NPN; external capacitor ensures low VCE(sat) and supports 100% duty cycle. |
| SS/TRACK1 (19) | Channel 1 soft-start & tracking control | 3.25µA constant-current source charges external cap; sets ramp rate and enables output tracking with SS/TRACK2. |
| VC1 (18) | Channel 1 error amplifier output | Drives peak current comparator; used for loop compensation, current clamping, or override control. |
| FB1 (17) | Channel 1 feedback input | Regulated to 0.8V; connects to resistor divider from VOUT1 - determines output voltage with ±2% accuracy. |
| RT/SYNC (16) | Frequency setting / sync input | Accepts resistor to GND (250kHz–1.5MHz) or external clock (250kHz–1.5MHz); auto-synchronizes with slope compensation. |
| SHDN (15) | Global shutdown control | 1.28V threshold; asserts low-quiescent shutdown (<10µA) and resets soft-start latches on both channels. |
| FB2 (14) | Channel 2 feedback input | Identical to FB1; enables independent or ratiometric regulation of second output voltage. |
| VC2 (13) | Channel 2 error amplifier output | Same function as VC1 but for Ch2; supports independent loop compensation and current limiting. |
| SS/TRACK2 (12) | Channel 2 soft-start & tracking control | Enables independent ramp timing or tracking with SS/TRACK1 via resistor network - supports sequencing. |
| BST2 (11) | Channel 2 bootstrap drive | Same function as BST1 but for Ch2; requires dedicated external boost capacitor for optimal efficiency. |
Key Features
| Feature | Design Value |
|---|---|
| Independent dual-channel control | Each channel has dedicated VIN, FB, SS/TRACK, PG, VC, IND, VOUT, and BST - enables true independent or coordinated regulation. |
| Antiphase 180° switching | Reduces input capacitor RMS current by ~30% and cuts peak input ripple amplitude - lowers required bulk capacitance. |
| Programmable tracking/sequencing | SS/TRACK1 and SS/TRACK2 pins support ratiometric, sequential, or absolute output voltage ramping - simplifies multi-rail power-up. |
| Enhanced dropout operation | ~95% max duty cycle via dynamic BST recharge management - sustains regulation with minimal VIN–VOUT headroom (e.g., 3.3V out from 3.6V input). |
| Robust short-circuit protection | Current-limit detection via IND/VOUT sensing with automatic foldback and soft-recovery - prevents thermal runaway during overload. |
| Low-noise shutdown mode | <10µA total quiescent current with SHDN asserted - meets stringent standby power budgets in always-on systems. |
Applications
| DSP Power Supplies | DSL/Cable Modems |
|---|---|
Use Scenario: Dual-rail core I/O supply for TI C6000 or Analog Devices SHARC processors requiring tightly tracked 1.2V/3.3V or 1.8V/3.3V rails with controlled power-up sequence. IC Role / Device Role / Timing Role: Primary dual-channel buck regulator delivering 3A per rail; uses SS/TRACK pins for ratiometric startup and PG pins for system reset assertion. Use Value: Eliminates need for external tracking ICs or discrete sequencing logic; antiphase operation reduces input filter size by 40% versus in-phase designs. |
Use Scenario: Compact, high-efficiency 3.3V/1.8V power solution for broadband access equipment operating from 12V wall adapter or PoE-derived input. IC Role / Device Role / Timing Role: Main DC/DC converter supplying PHY, MAC, and memory interfaces; leverages wide 3.1V–25V input range to accommodate varying upstream sources. Use Value: 95% max duty cycle enables stable 3.3V output even when input sags to 3.6V - improves system uptime during brownout conditions. |
| Disc Drives | Wall Transformer Regulation |
Use Scenario: Dual-output supply for HDD spindle motor driver (12V) and logic (3.3V/1.8V) in external storage enclosures powered from unregulated 15–19V adapters. IC Role / Device Role / Timing Role: High-current buck regulator handling transient loads up to 3A; uses independent VIN1/VIN2 to isolate motor noise from logic rails. Use Value: Independent input supplies prevent motor commutation noise from coupling into sensitive analog/digital circuits - improves data integrity. |
Use Scenario: Replacement for linear regulators in low-cost AC/DC wall adapters targeting 5V/3.3V dual outputs with >80% efficiency and minimal heat dissipation. IC Role / Device Role / Timing Role: Primary switching regulator converting rectified 9–18V DC to regulated outputs; utilizes fixed-frequency PWM for predictable EMI profile. Use Value: 250kHz–1.5MHz frequency range allows trade-off between transformer size (low freq) and efficiency (high freq) - optimizes BOM cost and thermal footprint. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3775EUF#PBF | Two-phase synchronous buck controller (external MOSFETs); supports up to 20A/channel; no integrated switches. | Requires external high-side/low-side MOSFETs, gate drivers, and bootstrap circuitry - larger solution size but higher efficiency at >5A loads. | Select LTC3775EUF#PBF when output current exceeds 3A or when >95% efficiency at full load is mandatory; not drop-in compatible. |
| TPS54386PWPR | Single-channel 3A synchronous buck converter; no dual-channel or tracking capability; 0.8V reference; 300kHz–2.2MHz frequency range. | Requires two separate ICs to replicate dual-rail functionality - increases component count, layout area, and sequencing complexity. | Choose TPS54386PWPR only for single-rail applications or where channel independence is unnecessary; pinout and control interface differ significantly. |
Compared with LTC3775EUF#PBF and TPS54386PWPR, the LT3501IFE#PBF uniquely integrates dual 3.5A NPN switches, independent tracking/sequencing, and antiphase operation in a single TSSOP-20 package - offering the smallest footprint and simplest design for ≤3A dual-rail systems requiring tight coordination.
Availability
LT3501IFE#PBF is available at Aetrix Electronics and suitable for DSP power supplies, DSL/cable modems, and disc drive applications requiring stable component supply, extended temperature operation (–40°C to 125°C), and high-current dual-rail integration.
Supply support for LT3501IFE#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 acquired Linear Technology in 2017 and maintains full product support, datasheets, and application engineering for legacy Linear parts including the LT3501 series.
The LT3501IFE#PBF belongs to Linear's high-performance power management portfolio, designed specifically for compact, high-current dual-rail DC/DC conversion in space-constrained industrial and communications equipment.
FAQ
What is the maximum output current per channel for the LT3501IFE#PBF?
The LT3501IFE#PBF supports up to 3A continuous output current per channel, enabled by its internal 3.5A NPN power switches and thermally enhanced 20-lead TSSOP package with exposed ground pad. Actual achievable current depends on PCB copper area, ambient temperature, and input/output voltage differential - derating is required above 85°C ambient.
Does the LT3501IFE#PBF support output voltage tracking between channels?
Yes, the LT3501IFE#PBF supports ratiometric, sequential, or absolute output voltage tracking using the SS/TRACK1 and SS/TRACK2 pins. Connecting these pins with resistors forms a tracking network that forces VOUT2 to follow VOUT1 during startup - essential for FPGA or processor core/I/O rail sequencing.
What is the purpose of the BST1 and BST2 pins on the LT3501IFE#PBF?
The BST1 and BST2 pins provide boosted gate drive voltage to the internal NPN power switches, ensuring low saturation voltage (<600mV at 3A) and high efficiency. Each requires an external capacitor (typically 0.1µF ceramic) from BSTx to SWx to generate a voltage ~VIN + 3V - critical for sustaining 95% duty cycle in dropout conditions.
Can the LT3501IFE#PBF operate with only one channel enabled?
Yes, the LT3501IFE#PBF allows independent channel disable via the SS/TRACK pins: pulling SS/TRACK1 or SS/TRACK2 low disables its respective channel while the other remains active. The global SHDN pin disables both channels simultaneously - useful for system-level power gating or fault recovery.
What is the minimum input voltage required for the LT3501IFE#PBF to regulate a 3.3V output?
The LT3501IFE#PBF can regulate a 3.3V output down to approximately 3.6V input due to its ~95% maximum duty cycle and boost capacitor management. At light loads, regulation may extend to ~3.45V input; however, full 3A output requires ≥3.6V input to maintain switch saturation and thermal stability.
LT3501IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-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):
- 3.1V
- Voltage - Input (Max):
- 25V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 23.75V
- Current - Output:
- 3A
- Frequency - Switching:
- 250kHz ~ 1.5MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP-EP
LT3501IFE#PBF FAQ
1.How can I place an order for LT3501IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3501IFE#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 LT3501IFE#PBF reliable?
The price and inventory of LT3501IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3501IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3501IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3501IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3501IFE#PBF?
LT3501IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3501IFE#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 LT3501IFE#PBF?
For technical support, including LT3501IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3501IFE#PBF requirements.
6.How does Aetrix verify that LT3501IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3501IFE#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 LT3501IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3501IFE#PBF?
All LT3501IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3501IFE#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 LT3501IFE#PBF part is unused and in its original packaging.
Return procedure for LT3501IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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