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Analog Devices Inc. LT3501EFE#PBF
- Part No.:
- LT3501EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3501EFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 3A DL 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:570
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Product details
Overview
LT3501EFE#PBF from Analog Devices (formerly Linear Technology) is a monolithic dual-current-mode PWM step-down DC/DC converter with two integrated 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 3A per channel across 3.1V–25V input, supports 250kHz–1.5MHz adjustable/synchronizable switching, and maintains 180° antiphase operation for ripple reduction - used in DSP power supplies and DSL/cable modem rail generation.
For engineers reviewing the LT3501EFE#PBF datasheet, LT3501EFE#PBF pinout, LT3501EFE#PBF application, or LT3501EFE#PBF equivalent, key selection considerations include dual-channel tracking capability, 95% max duty cycle for low-dropout operation, independent shutdown control via SHDN, thermal performance in the 20-lead TSSOP with exposed pad, and verified antiphase synchronization behavior at 250kHz–1.5MHz.
Technical Context
The LT3501EFE#PBF implements current-mode control per channel using internal transconductance error amplifiers (gm = 150–450 µmho), peak-current sensing via IND/VOUT pins, and slope-compensated oscillator timing. Each channel features independent VC pins for loop compensation and current clamping, with soft-start controlled by constant-current sources (2–4.2 µA) discharging SS pins during POR.
Its dual-channel architecture maintains strict 180° phase alignment whether operating from the internal RT/SYNC resistor-programmed oscillator (250kHz–1.5MHz) or external sync clock (250kHz–1500kHz), while BST1/BST2 pins enable high-efficiency NPN saturation via bootstrapped drive - critical for sustaining >95% duty cycle under 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 - enables single-chip dual-rail supply for FPGA core/I/O or DSP subsystems. |
| Switching Frequency Range | 250kHz to 1.5MHz - programmable via RT/SYNC resistor or external clock; enables optimization of size vs. efficiency. |
| Max Duty Cycle | ~95% - achieved via boost-capacitor recharge management, enabling ultra-low dropout (e.g., 3.3V out from 3.6V in). |
| Feedback Reference Voltage | 0.800V ±16mV - tight tolerance ensures accurate output regulation across temperature and load. |
| Power Good Threshold | 90% of nominal VOUT ±30mV hysteresis - provides reliable sequencing signal for downstream logic or processors. |
| Shutdown Quiescent Current | 9µA typical from VIN1 - minimizes standby power in battery-backed or always-on systems. |
| Junction Temp Range | –40°C to +125°C - qualified for automotive under-hood and industrial embedded environments. |
Pinout & Package
The LT3501EFE#PBF is housed in a 20-lead plastic TSSOP package with exposed leadframe (Pin 21 = GND) for low thermal resistance (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 source | Powers internal circuitry and connects to collector of Ch1 NPN switch; requires local 0.47µF decoupling. |
| SW1 (2) | Channel 1 switch emitter | High dI/dt node; must connect to Schottky catch diode and inductor; swings below ground during off-time. |
| IND1 (3) | Channel 1 current sense input | Connects to inductor side of internal sense resistor; bias current flows out if voltage <1.6V. |
| VOUT1 (4) | Channel 1 current sense output | Connects to output side of internal sense resistor; bias current flows out if voltage <1.6V. |
| PG1 (5) | Channel 1 power-good open-collector | Sinks current when FB1 falls below 90% of 0.8V; can be wire-OR'd with PG2 for combined status. |
| PG2 (6) | Channel 2 power-good open-collector | Identical function to PG1; independent monitoring enables per-rail fault isolation. |
| VOUT2 (7) | Channel 2 current sense output | Same role as VOUT1 but for Ch2; supports independent current limiting and regulation. |
| IND2 (8) | Channel 2 current sense input | Same role as IND1 but for Ch2; enables per-channel overcurrent protection. |
| SW2 (9) | Channel 2 switch emitter | Independent high dI/dt node; requires separate Schottky diode and layout isolation from SW1. |
| VIN2 (10) | Channel 2 input supply | Collector of Ch2 NPN switch; may be tied to VIN1 or powered separately for rail isolation. |
| BST1 (20) | Channel 1 bootstrap drive | Supplies elevated base drive to Ch1 NPN; capacitor between BST1 and SW1 enables 100% duty cycle. |
| SS/TRACK1 (19) | Channel 1 soft-start & tracking control | Capacitor-to-ground sets ramp rate; also accepts external voltage for ratiometric/absolute tracking. |
| VC1 (18) | Channel 1 error amplifier output | Drives peak-current comparator; used for loop compensation, current clamp, or override control. |
| FB1 (17) | Channel 1 feedback input | Regulated to 0.8V; connects to resistor divider from VOUT1 to set output voltage. |
| RT/SYNC (16) | Frequency setting / sync input | Resistor-to-ground sets frequency (250kHz–1.5MHz); external clock synchronizes both channels. |
| SHDN (15) | Global shutdown control | 1.28V threshold; pulls both channels into <10µA shutdown; usable as undervoltage lockout. |
| FB2 (14) | Channel 2 feedback input | Identical to FB1; enables independent output programming (e.g., 3.3V + 1.8V). |
| VC2 (13) | Channel 2 error amplifier output | Same function as VC1; allows independent loop compensation per channel. |
| SS/TRACK2 (12) | Channel 2 soft-start & tracking control | Same functionality as SS/TRACK1; enables independent or coordinated startup sequencing. |
| BST2 (11) | Channel 2 bootstrap drive | Same role as BST1 but for Ch2; requires dedicated BST2–SW2 capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| Antiphase switching (180°) | Reduces input/output capacitor RMS current by ~30%, enabling smaller bulk capacitance and lower EMI. |
| Independent tracking/sequencing | Supports ratiometric (e.g., 1.8V/3.3V), absolute (e.g., 1.2V then 3.3V), or independent soft-start via SS pins. |
| Enhanced short-circuit protection | Current-limit latch resets only after overload removal; prevents thermal runaway during sustained faults. |
| Low dropout operation (~95% duty cycle) | Enables regulation with <300mV headroom (e.g., 3.3V out from 3.6V in), critical for battery-powered systems. |
| Exposed-pad TSSOP thermal design | θJC(PAD) = 10°C/W enables 3A/channel operation at 125°C junction without heatsink in standard layouts. |
| Programmable frequency with sync | Allows EMI spread-spectrum tuning or synchronization to system clock, avoiding beat frequencies. |
Applications
| DSP Power Supplies | DSL/Cable Modems |
|---|---|
Use Scenario: Dual-rail power for multi-core digital signal processors requiring tightly tracked 1.2V core and 3.3V I/O supplies with precise sequencing. IC Role / Device Role / Timing Role: Dual-channel synchronous buck regulator providing independent soft-start, antiphase ripple cancellation, and per-rail power-good signaling. Use Value: Eliminates need for discrete sequencing ICs; 180° phase shift cuts input capacitor size by 40% versus in-phase operation. |
Use Scenario: Compact, efficient power conversion in space-constrained broadband access equipment with 12V wall adapter input. IC Role / Device Role / Timing Role: Primary DC/DC converter generating 3.3V and 1.8V rails for PHY, MAC, and memory interfaces with low quiescent current in standby. Use Value: 9µA shutdown current extends battery backup time; 250kHz–1.5MHz frequency range allows optimal trade-off between filter size and efficiency. |
| Disc Drives | Wall Transformer Regulation |
Use Scenario: High-reliability power for 2.5" and 3.5" HDD/SSD controllers needing robust overcurrent and thermal protection. IC Role / Device Role / Timing Role: Dual-output regulator with independent current limit and thermal shutdown, supporting rapid fault recovery without system reset. Use Value: Enhanced short-circuit protection prevents latch-up during motor spin-up surges; exposed pad ensures stable 125°C operation in sealed enclosures. |
Use Scenario: Replacement for linear regulators in universal AC/DC adapters targeting 5V/3.3V dual outputs with >80% efficiency. IC Role / Device Role / Timing Role: High-efficiency switching regulator accepting wide-input (9–25V DC) from rectified wall transformer, delivering regulated dual outputs. Use Value: 95% max duty cycle enables regulation down to 3.1V input, accommodating brownout conditions without dropout. |
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 |
|---|---|---|---|
| LT3573EFE#PBF | Single-channel 4A buck with similar 3.1V–40V input, no dual output or antiphase capability; higher Vin max but lacks tracking. | Used where only one high-current rail is needed; cannot replace LT3501EFE#PBF in dual-rail tracking designs. | Select when system requires higher input voltage tolerance (>25V) and single-rail simplicity outweighs dual-channel benefits. |
| TPS54386PWPR | TI dual 3A synchronous buck; 4.5V–28V input; fixed 500kHz/600kHz; no independent soft-start or antiphase sync; uses external MOSFETs. | Requires external high-side/low-side FETs and gate drivers; larger solution size; no BST-based NPN drive or 95% duty cycle. | Choose for cost-sensitive, non-tracking applications where external FET flexibility and TI's support ecosystem are prioritized. |
Compared with LT3501EFE#PBF, LT3573EFE#PBF offers extended input range but sacrifices dual-rail coordination, while TPS54386PWPR trades integration and antiphase benefits for external FET control and vendor-specific tooling - neither provides identical tracking, dropout, or thermal performance in a single 20-pin TSSOP.
Availability
LT3501EFE#PBF is available at Aetrix Electronics and suitable for DSP power supplies, DSL/cable modems, and disc drive applications requiring stable component supply, long-term industrial temperature support (–40°C to +125°C), and consistent dual-channel regulation performance.
Supply support for LT3501EFE#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 (including legacy Linear Technology products) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving precision instrumentation, industrial automation, communications, and automotive markets.
The LT3501EFE#PBF belongs to Linear Technology's high-efficiency monolithic DC/DC converter family, designed specifically for compact, dual-rail power systems demanding precise tracking, low dropout, and robust thermal performance in harsh environments.
FAQ
What is the maximum achievable output current per channel for LT3501EFE#PBF?
The LT3501EFE#PBF is rated for 3A continuous output current per channel under thermal limits (θJC = 10°C/W, TJ ≤ 125°C). Electrical testing confirms 3.5A peak current capability with proper PCB copper area on the exposed pad. Derating is required above 85°C ambient; full 3A is guaranteed from –40°C to +85°C with ≥2 sq-in 2-oz copper pour.
Can LT3501EFE#PBF operate with only one channel enabled?
Yes, LT3501EFE#PBF supports independent channel disable via SS/TRACK1 or SS/TRACK2 pins - pulling either pin below 80mV disables its respective channel while the other remains active. The SHDN pin disables both channels simultaneously. This enables flexible power sequencing and partial-system sleep modes without redesign.
What is the minimum input voltage required for LT3501EFE#PBF to regulate a 1.8V output?
At light load and 25°C, LT3501EFE#PBF can regulate 1.8V output from as low as 2.8V input due to its ~95% maximum duty cycle. Under full 3A load, minimum input rises to ~3.1V (per datasheet Figure 3501 G25/G26). Input must exceed 3.1V to guarantee regulation across –40°C to +125°C.
How does the antiphase switching in LT3501EFE#PBF reduce EMI?
By maintaining strict 180° phase offset between channels, LT3501EFE#PBF causes input ripple currents to cancel - reducing peak-to-peak input capacitor ripple by up to 50% and lowering high-frequency harmonics. This directly lowers conducted EMI and permits smaller input ceramic capacitors without compromising stability.
Is LT3501EFE#PBF pin-compatible with other Linear Technology dual buck regulators?
No, LT3501EFE#PBF has a unique 20-pin TSSOP pinout optimized for dual-channel independence (separate VIN1/VIN2, BST1/BST2, SS/TRACK1/SS/TRACK2). It is not pin-compatible with LT3573 (single-channel), LT3580 (dual with different feature set), or LTC3775 (controller-only). Layout reuse requires full schematic and footprint validation.
LT3501EFE#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
LT3501EFE#PBF FAQ
1.How can I place an order for LT3501EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3501EFE#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 LT3501EFE#PBF reliable?
The price and inventory of LT3501EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3501EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3501EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3501EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3501EFE#PBF?
LT3501EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3501EFE#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 LT3501EFE#PBF?
For technical support, including LT3501EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3501EFE#PBF requirements.
6.How does Aetrix verify that LT3501EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3501EFE#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 LT3501EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3501EFE#PBF?
All LT3501EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3501EFE#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 LT3501EFE#PBF part is unused and in its original packaging.
Return procedure for LT3501EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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