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Analog Devices Inc. LT3506EFE#PBF
- Part No.:
- LT3506EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3506EFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.6A DL 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,499
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Product details
Overview
LT3506EFE#PBF from Analog Devices (formerly Linear Technology) is a dual monolithic current-mode PWM step-down DC/DC converter with internal 2A bipolar NPN power switches, delivering two independent 1.6A outputs. It operates from 3.6V to 25V input, features 575kHz fixed switching frequency, anti-phase operation to reduce input ripple, and independent shutdown, soft-start, and power-good signals - used in DSP power supplies and distributed power regulation.
For engineers reviewing the LT3506EFE#PBF datasheet, LT3506EFE#PBF pinout, LT3506EFE#PBF application, or LT3506EFE#PBF equivalent, key selection criteria include its 16-lead TSSOP package, ±1% 0.8V feedback reference, thermal shutdown protection, frequency foldback under overload, and dual-channel sequencing capability for multi-rail embedded systems.
Technical Context
The LT3506EFE#PBF implements a constant-frequency current-mode control architecture with shared master oscillator and independent slave oscillators per channel, enabling precise duty-cycle control and fast transient response. Each regulator uses an internal error amplifier (gm = 350 μMhos) to drive the VC pin, which directly modulates peak switch current via a 0.75V threshold and 1.9V clamp.
Anti-phase switching (180° phase shift) between channels minimizes input capacitor RMS current, while slope compensation prevents subharmonic oscillation above 50% duty cycle. Frequency foldback activates when FB falls below 0.4V, reducing switching frequency to ~170kHz during overloads or short circuits to limit power dissipation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 25V - supports 4-cell Li-ion, 5V logic rails, unregulated wall adapters, and lead-acid batteries without external pre-regulation. |
| Switching Frequency | 575kHz - enables use of compact 2.2–6.4μH inductors and ceramic output capacitors for space-constrained designs. |
| Output Current per Channel | 1.6A continuous - sustained at VOUT ≥ 1.8V with proper inductor selection (e.g., Sumida CR43-4R7 or Coilcraft DO1606T-222). |
| Feedback Reference Voltage | 0.8V ±1% - ensures accurate output regulation across –40°C to +85°C operating range with minimal resistor-divider error. |
| Power-Good Threshold | 720mV rising on FB - provides reliable sequencing signal when output reaches 90% of target voltage, compatible with microcontroller reset inputs. |
| Switch Current Limit | 2.0A minimum - protects internal bipolar NPN switches during startup, overload, or short-circuit events with cycle-by-cycle limiting. |
| Quiescent Current | 3.8mA - measured at VIN = 5V with both regulators enabled, enabling efficient operation in always-on subsystems. |
Pinout & Package
LT3506EFE#PBF is housed in a 16-lead plastic TSSOP narrow package (FE) with exposed pad (Pin 17) soldered to PCB for thermal and electrical grounding. Package dimensions: 5mm × 4.4mm × 1.2mm, θJA = 45°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST1 (1), BOOST2 (8) | Bootstrap drive supply | Provides >VIN gate drive to internal NPN switches via external diode+capacitor; enables full saturation and low VCESAT (~210mV). |
| SW1 (2), SW2 (7) | Switch node output | Connects to inductor, catch diode, and boost capacitor; carries high di/dt pulsed current requiring tight layout and ground plane coupling. |
| VIN1 (3,4), VIN2 (5,6) | Input power supply | VIN1 powers internal bias regulator and Channel 1 switch; VIN2 powers Channel 2 switch only - allows independent input sourcing. |
| RUN/SS1 (13), RUN/SS2 (12) | Enable & soft-start control | Pull low to disable respective channel; connect capacitor to ground for controlled current ramp and inrush limiting during startup. |
| PG1 (14), PG2 (11) | Open-collector power-good | Sinks current when FB < 720mV; requires external pull-up to sequence downstream rails or assert MCU reset. |
| VC1 (15), VC2 (10) | Error amplifier output | Directly controls peak switch current; clamped at 0.75V turn-on and 1.9V max - usable for loop compensation or external override. |
| FB1 (16), FB2 (9) | Feedback input | Regulated to 0.8V ±1%; connects to resistor divider tap - sets output voltage as VOUT = 0.8V × (1 + R1/R2). |
| Exposed Pad (17) | Thermal & ground connection | Must be soldered to PCB ground plane to meet θJC = 10°C/W and prevent thermal shutdown at full load. |
Key Features
| Feature | Design Value |
|---|---|
| Anti-phase switching | Reduces input ripple current by up to 50% versus in-phase operation, allowing smaller input capacitors (e.g., 4.7μF X7R ceramic). |
| Independent power-good signals | Enables precise sequencing of dual-rail supplies (e.g., core + I/O) without external timing circuitry or microcontroller intervention. |
| Internal 2A bipolar NPN switches | Eliminates need for external MOSFETs and drivers; achieves 210mV VCESAT at 1A, supporting high efficiency (>85% at 1.8V/1.6A, VIN=5V). |
| Frequency foldback protection | Automatically reduces switching frequency to ~170kHz during overload, limiting peak switch current and junction temperature rise. |
| Thermal shutdown | Activates at TJ = 125°C and holds off until die cools by ~15°C - prevents permanent damage during sustained overloads or poor heatsinking. |
Applications
| DSP Power Supplies | Wall Transformer Regulation |
|---|---|
Use Scenario: Providing tightly regulated 1.2V core and 3.3V I/O rails for TI C6000 or Analog Devices SHARC processors in portable test equipment. IC Role / Device Role / Timing Role: Dual-output buck controller generating synchronized, sequenced voltages with independent PGOOD signaling for processor boot integrity. Use Value: Eliminates discrete regulators and sequencing ICs; achieves <1% output deviation across load steps using internal 0.8V reference and current-mode control. | Use Scenario: Regulating noisy, unregulated 12V–24V AC/DC wall adapter outputs into clean 5V and 3.3V rails for IoT gateway baseboards. IC Role / Device Role / Timing Role: Primary DC/DC conversion stage accepting wide-input industrial-grade adapters while suppressing conducted EMI via anti-phase switching. Use Value: Maintains regulation down to 3.6V input, enabling brownout tolerance; 575kHz operation allows use of low-profile 2.2μH inductors (<3.5mm height) in space-limited enclosures. |
| Distributed Power Regulation | Disk Drive Power Management |
Use Scenario: Local point-of-load conversion in modular server backplanes where 12V or 48V intermediate bus feeds multiple isolated boards. IC Role / Device Role / Timing Role: Dual-channel POL regulator delivering independent 1.8V and 2.5V supplies to FPGA I/O banks and memory interfaces with thermal-aware derating. Use Value: Exposed-pad TSSOP package enables direct thermal coupling to copper pour; shutdown current <45μA supports low-power sleep states without rail collapse. | Use Scenario: Powering spindle motor driver and SATA interface circuitry in 2.5" enterprise SSDs with strict thermal and EMI constraints. IC Role / Device Role / Timing Role: High-efficiency dual buck supplying 5V motor drive and 1.5V logic rails, leveraging frequency foldback to survive motor stall currents. Use Value: Internal 2A switches withstand 2.6A current limit peaks; soft-start prevents inrush-induced voltage droop on shared 5V bus during spin-up. |
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 |
|---|---|---|---|
| LTC3631EFE#PBF | Single-channel 3A buck; 3MHz switching; no anti-phase or dual-PG; requires external compensation. | Not suitable for dual-rail sequencing; better for ultra-compact single-output apps needing higher frequency. | Select only if single-output capacity >2A is required and sequencing is handled externally. |
| TPS54290PWPR | Dual-channel 2A buck; 300–2000kHz adjustable frequency; integrated FETs; no frequency foldback; different pinout. | Requires external soft-start and sequencing logic; lacks independent PGOOD per channel. | Prefer when design flexibility (frequency tuning, external sync) outweighs need for built-in sequencing and fault protection. |
Compared with LTC3631EFE#PBF and TPS54290PWPR, the LT3506EFE#PBF uniquely delivers dual independent 1.6A outputs with anti-phase operation, integrated sequencing via dual PGOOD, and frequency foldback - making it optimal for space-constrained, multi-rail embedded systems requiring robust fault handling without external components.
Availability
LT3506EFE#PBF is available at Aetrix Electronics and suitable for DSP power supplies, wall transformer regulation, and distributed power regulation requiring stable component supply across industrial temperature ranges (–40°C to +85°C).
Supply support for LT3506EFE#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 its legacy of high-performance analog and power management ICs with rigorous automotive and industrial qualification.
The LT3506 product line was designed specifically for compact, high-reliability dual-output DC/DC conversion in datacom, storage, and portable instrumentation where input ripple reduction and supply sequencing are critical.
FAQ
What is the maximum supported input voltage for LT3506EFE#PBF?
The LT3506EFE#PBF has an absolute maximum VIN rating of 25V, but its functional maximum depends on output voltage and duty cycle. With DCMAX = 89%, it supports up to ~21V at VOUT = 1.2V and ~15V at VOUT = 0.8V. Transient inputs may reach 25V briefly, but sustained operation above calculated limits risks loss of regulation or thermal stress. Always verify minimum duty cycle requirements per application.
Does LT3506EFE#PBF support synchronization to an external clock?
No, the LT3506EFE#PBF does not support external clock synchronization. It uses an internal master oscillator that sets both channels' switching frequency at 575kHz (fixed). The two channels operate in anti-phase (180° offset) but cannot be synced to an external source. For sync-capable alternatives, consider the LTC3851A or TPS546B24A.
Can LT3506EFE#PBF drive ceramic output capacitors exclusively?
Yes, the LT3506EFE#PBF is fully compatible with ceramic output capacitors due to its current-mode control architecture, which does not require ESR for loop stability. A 22μF X7R/X5R ceramic capacitor is recommended for 3.3V/5V outputs delivering ≥1A, providing low ripple (<10mVpp) and excellent transient response without electrolytic supplementation.
How is thermal performance affected by the exposed pad on LT3506EFE#PBF?
The exposed pad (Pin 17) of the LT3506EFE#PBF must be soldered to a PCB ground plane to achieve θJA = 45°C/W and prevent thermal shutdown. Without proper pad soldering, junction temperature can exceed 125°C at full 1.6A load per channel. Recommended layout includes ≥4 thermal vias (0.3mm diameter) connecting the pad to inner ground layers.
What happens to LT3506EFE#PBF during an output short-circuit condition?
During an output short, the LT3506EFE#PBF activates frequency foldback, reducing switching frequency from 575kHz to ~170kHz to limit average switch current and power dissipation. Combined with cycle-by-cycle current limiting (2.0A min) and thermal shutdown at 125°C, this protects both the IC and external components. Recovery is automatic once fault clears and FB rises above 720mV.
LT3506EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-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):
- 3.6V
- Voltage - Input (Max):
- 25V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 23.25V
- Current - Output:
- 1.6A
- Frequency - Switching:
- 575kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3506EFE#PBF FAQ
1.How can I place an order for LT3506EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3506EFE#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 LT3506EFE#PBF reliable?
The price and inventory of LT3506EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3506EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3506EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3506EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3506EFE#PBF?
LT3506EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3506EFE#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 LT3506EFE#PBF?
For technical support, including LT3506EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3506EFE#PBF requirements.
6.How does Aetrix verify that LT3506EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3506EFE#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 LT3506EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3506EFE#PBF?
All LT3506EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3506EFE#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 LT3506EFE#PBF part is unused and in its original packaging.
Return procedure for LT3506EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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