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Analog Devices Inc. LT3501EFE#TRPBF
- Part No.:
- LT3501EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3501EFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 3A DL 20TSSOP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT3501EFE#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic dual-current-mode PWM step-down DC/DC converter with two internal 3.5A NPN switches, designed for high-efficiency, tightly regulated dual-output power supplies in space-constrained systems. It supports independent input rails (VIN1/VIN2), 3.1V–25V wide input range, 95% max duty cycle for ultra-low dropout, and antiphase 180° switching at 250kHz–1.5MHz to reduce input ripple and EMI.
For engineers reviewing the LT3501EFE#TRPBF datasheet, LT3501EFE#TRPBF pinout, LT3501EFE#TRPBF application, or LT3501EFE#TRPBF equivalent, key selection criteria include dual-channel tracking/sequencing capability, independent soft-start and power-good signaling per channel, resistor-programmable or external-synchronized frequency control, and thermal performance enabled by its exposed-pad 20-lead TSSOP package.
Technical Context
The LT3501EFE#TRPBF 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 timing. Each channel features independent feedback (0.8V ±2%), VC clamp (2.0V typ), and soft-start with 3.25µA source current - enabling precise output ramping and overload recovery.
Its dual-channel architecture maintains strict 180° phase alignment across all operating frequencies (250kHz–1.5MHz), whether set by RT/SYNC resistor or external clock, while BST1/BST2 boost capacitor management enables >95% duty cycle operation under low VIN–VOUT conditions without sacrificing switch saturation (250–600mV at 3A).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.1V to 25V - supports wide-range industrial, telecom, and wall-adapter inputs without pre-regulation. |
| Output Current per Channel | 3.5A continuous - sufficient for DSP cores, FPGA I/O banks, or dual-core processors with independent voltage domains. |
| Feedback Reference Voltage | 0.800V ±2% - enables accurate, stable output regulation with minimal resistor-divider error sensitivity. |
| Switching Frequency Range | 250kHz to 1.5MHz - programmable via RT/SYNC resistor or external sync signal; allows trade-off between efficiency and component size. |
| Channel Phase Relationship | 180° antiphase - reduces input capacitor RMS current and system-level voltage ripple by up to 30% vs in-phase operation. |
| Max Duty Cycle | ~95% - achieved via boost-capacitor–managed minimum off-time control, enabling operation down to VIN–VOUT < 0.5V. |
| Shutdown Quiescent Current | 9µA (Ch1), <1µA (Ch2) - ensures ultra-low standby power in battery-backed or always-on systems. |
Pinout & Package
The LT3501EFE#TRPBF is housed in a 20-lead plastic TSSOP package with exposed leadframe (Pin 21 = GND), optimized for low thermal resistance (θJC(PAD) = 10°C/W). The exposed pad must be soldered to PCB ground plane for proper thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN1 (1) | Channel 1 input supply & bias rail | Powers internal control circuitry and serves as collector for Ch1 NPN switch; requires local high-frequency decoupling. |
| SW1 (2) | Channel 1 switch emitter | High dI/dt node requiring Schottky catch diode to ground; connects directly to inductor and output filter. |
| IND1 (3) | Channel 1 current sense input | Inputs inductor current signal to internal comparator; bias current flows out when voltage < 1.6V. |
| VOUT1 (4) | Channel 1 current sense return | Completes current-sense path; bias current flows out when voltage < 1.6V; tied to output capacitor negative terminal. |
| PG1 (5) | Channel 1 power-good open-collector | Sinks current when FB1 falls below 90% of 0.8V; used for system sequencing and fault indication. |
| PG2 (6) | Channel 2 power-good open-collector | Independent PG signal for Ch2; can be wired in parallel with PG1 for combined status reporting. |
| VOUT2 (7) | Channel 2 current sense return | Same function as VOUT1 but for Ch2; enables independent current monitoring per output. |
| IND2 (8) | Channel 2 current sense input | Same function as IND1 but for Ch2; supports independent overcurrent protection per channel. |
| SW2 (9) | Channel 2 switch emitter | Identical to SW1 but for Ch2; requires separate Schottky diode and local decoupling. |
| VIN2 (10) | Channel 2 input supply | Independent collector rail for Ch2 NPN switch; may be tied to VIN1 or isolated for dual-input designs. |
| BST1 (20) | Channel 1 bootstrap drive | Provides >VIN base drive to Ch1 NPN; capacitor must be placed close to pin for reliable 100% duty cycle. |
| SS/TRACK1 (19) | Channel 1 soft-start & tracking control | 3.25µA constant-current source sets output ramp rate; also accepts external tracking voltage for ratiometric sequencing. |
| VC1 (18) | Channel 1 error amplifier output | Drives peak-current comparator; used for loop compensation, current limiting, or external override. |
| FB1 (17) | Channel 1 feedback input | Regulated to 0.8V; connects to resistor divider from VOUT1 to set output voltage precisely. |
| RT/SYNC (16) | Frequency setting & sync input | Accepts resistor to ground (250kHz–1.5MHz) or external clock (250kHz–1.5MHz); auto-detects sync mode. |
| SHDN (15) | Global shutdown control | 1.28V threshold; pulls both channels into <10µA shutdown; usable as undervoltage lockout. |
| FB2 (14) | Channel 2 feedback input | Same function as FB1 but for Ch2; enables independent output voltage programming. |
| VC2 (13) | Channel 2 error amplifier output | Same function as VC1 but for Ch2; supports independent loop compensation per channel. |
| SS/TRACK2 (12) | Channel 2 soft-start & tracking control | Same function as SS/TRACK1 but for Ch2; enables independent or coordinated startup. |
| BST2 (11) | Channel 2 bootstrap drive | Same function as BST1 but for Ch2; requires dedicated boost capacitor and layout isolation. |
Key Features
| Feature | Design Value |
|---|---|
| Independent dual-channel control | Each channel has dedicated VIN, FB, SS/TRACK, PG, VC, IND, VOUT, and BST - enabling fully decoupled design or flexible tracking/sequencing. |
| Antiphase 180° switching | Reduces input capacitor RMS current by ~70%, allowing smaller bulk capacitance and lower EMI filtering cost. |
| Programmable 250kHz–1.5MHz frequency | Enables optimization: higher frequencies shrink inductors/capacitors; lower frequencies maximize efficiency at light loads. |
| 95% maximum duty cycle with dropout enhancement | Maintains regulation even when VIN drops within ~0.3V of VOUT - critical for battery-powered or brownout-prone systems. |
| Independent soft-start and power-good per channel | Supports complex power-up sequences (e.g., core before I/O) and real-time fault detection without cross-channel coupling. |
| Enhanced short-circuit protection | Current-limiting via IND/VOUT sensing + VC clamping + soft-start discharge ensures graceful foldback and recovery under overload. |
Applications
| DSP Power Supplies | Disc Drives |
|---|---|
|
Use Scenario: Powering dual-voltage DSP subsystems requiring 1.2V core and 3.3V I/O with tight sequencing and low noise. IC Role / Device Role / Timing Role: Dual synchronous buck regulator delivering 3A per rail with independent soft-start and antiphase ripple cancellation. Use Value: Eliminates need for discrete sequencing ICs; 180° phase shift cuts input ripple by >50%, reducing bulk capacitor count by 2×. |
Use Scenario: Regulating motor driver and servo control voltages in optical disc drives with rapid load transients. IC Role / Device Role / Timing Role: High-current dual buck supplying 5V actuator and 3.3V logic rails with fast transient response and overload foldback. Use Value: Internal 3.5A switches and current-mode control deliver <10µs response to 2A load steps; BST-enhanced dropout prevents brownout during spin-up. |
| DSL/Cable Modems | Wall Transformer Regulation |
|
Use Scenario: Generating isolated 12V, 5V, and 3.3V rails from unregulated 15–24V AC/DC adapter output in broadband gateways. IC Role / Device Role / Timing Role: Dual adjustable buck converter supporting ratiometric tracking (e.g., 5V/3.3V) with shared RT/SYNC clock for EMI reduction. Use Value: Single-chip solution replaces two discrete regulators; synchronized 500kHz operation allows common EMI filter design and layout reuse. |
Use Scenario: Replacing linear regulators in universal wall adapters to improve efficiency and thermal performance at 3A loads. IC Role / Device Role / Timing Role: High-efficiency dual buck converting 12V–24V DC input to 5V USB and 3.3V logic outputs with <10µA shutdown current. Use Value: 83.9% efficiency at 500kHz (vs ~40% for LDOs) cuts thermal dissipation by >60%; exposed-pad TSSOP enables compact heatsinking. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3573EUF#TRPBF | Single-channel 4A buck with integrated MOSFETs; no dual-output or tracking capability; 3.1V–40V input. | Requires two devices for dual-rail designs; lacks independent PG/SS pins and antiphase operation. | Choose when higher input voltage (>25V) or single-rail simplicity outweighs dual-channel integration. |
| TPS543B20RJER | Single-channel 12A buck with PMBus interface; 4.5V–18V input; no native dual-channel or tracking support. | Needs external sequencing logic; offers digital telemetry but no analog tracking/soft-start flexibility. | Prefer when telemetry, margining, or dynamic voltage scaling are required over analog simplicity and dual-rail integration. |
Compared with LT3573EUF#TRPBF and TPS543B20RJER, the LT3501EFE#TRPBF uniquely integrates two fully independent 3.5A buck channels with analog tracking, antiphase switching, and sub-10µA shutdown - making it optimal for cost-sensitive, space-constrained dual-rail systems where digital control adds unnecessary complexity.
Availability
LT3501EFE#TRPBF is available at Aetrix Electronics and suitable for DSP power supplies, disc drive motor/logic regulation, and DSL/cable modem distributed power requiring stable component supply, long-term lifecycle assurance, and consistent parametric performance across temperature.
Supply support for LT3501EFE#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 and maintains full product support, documentation, and manufacturing continuity for the LT® portfolio.
The LT3501EFE#TRPBF belongs to Linear's high-performance monolithic DC/DC converter family, engineered for demanding analog-intensive applications including telecom infrastructure, test equipment, and industrial control where precision regulation, low noise, and robust thermal behavior are essential.
FAQ
What is the operating junction temperature range for the LT3501EFE#TRPBF?
The LT3501EFE#TRPBF is rated for –40°C to 125°C operating junction temperature. This grade (E-grade) is assured by design across the full range, with performance specifications guaranteed from 0°C to 125°C and characterized down to –40°C. Thermal derating is not required until TJ exceeds 125°C, where overtemperature protection activates.
Can the LT3501EFE#TRPBF operate with only one channel enabled?
Yes, the LT3501EFE#TRPBF supports independent channel enablement. Driving SS/TRACK1 or SS/TRACK2 low disables its respective channel while leaving the other active. Alternatively, pulling SHDN low places both channels in shutdown (<10µA total IQ). This flexibility enables partial-power modes in multi-rail systems without redesign.
How does the LT3501EFE#TRPBF achieve 95% maximum duty cycle?
The LT3501EFE#TRPBF achieves ~95% duty cycle by dynamically extending on-time when the BST capacitor voltage remains sufficient to saturate the internal NPN switch. If BST voltage drops below the minimum threshold (~1.7V), a comparator forces a minimum off-time to recharge the capacitor - maintaining regulation even when VIN approaches VOUT.
What external components are mandatory for basic LT3501EFE#TRPBF operation?
Each channel requires: one Schottky catch diode (e.g., PMEG4005), one output inductor (e.g., 3.3µH), one output capacitor (e.g., 47µF), one feedback divider (two 1% resistors), one BST capacitor (e.g., 0.1µF ceramic), and one soft-start capacitor (e.g., 10nF). VIN1/VIN2 and GND must be locally decoupled with ≥0.47µF X7R ceramics.
Is the LT3501EFE#TRPBF pin-compatible with other LT35xx devices?
No, the LT3501EFE#TRPBF is not pin-compatible with other LT35xx parts. Its 20-lead TSSOP pinout is unique to the dual-channel architecture - e.g., LT3573 uses a 24-pin QFN, and LT3510 is a single-channel 16-lead TSSOP. Layout reuse requires verification against the LT3501EFE#TRPBF-specific pin map and thermal pad requirements.
LT3501EFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-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):
- 3.1V
- 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
LT3501EFE#TRPBF FAQ
1.How can I place an order for LT3501EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3501EFE#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 LT3501EFE#TRPBF reliable?
The price and inventory of LT3501EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3501EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3501EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3501EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3501EFE#TRPBF?
LT3501EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3501EFE#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 LT3501EFE#TRPBF?
For technical support, including LT3501EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3501EFE#TRPBF requirements.
6.How does Aetrix verify that LT3501EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3501EFE#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 LT3501EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3501EFE#TRPBF?
All LT3501EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3501EFE#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 LT3501EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3501EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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