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Analog Devices Inc. LT3506AIDHD#PBF
- Part No.:
- LT3506AIDHD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-WFDFN Exposed Pad
- Datasheet:
-
LT3506AIDHD#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.6A DL 16DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,845
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Product details
Overview
LT3506AIDHD#PBF from Analog Devices (formerly Linear Technology) is a dual monolithic current-mode PWM step-down DC/DC converter with two integrated 2A bipolar NPN power switches, delivering up to 1.6A per channel. It operates at a fixed 1.1MHz switching frequency, supports 3.6V–25V input, regulates outputs via external resistor dividers, and provides independent shutdown, soft-start, and power-good signals for sequencing in multi-rail systems such as DSP power supplies and DSL modems.
For engineers reviewing the LT3506AIDHD#PBF datasheet, LT3506AIDHD#PBF pinout, LT3506AIDHD#PBF application, or LT3506AIDHD#PBF equivalent, key selection considerations include its 1.1MHz constant-frequency operation, anti-phase switching for reduced input ripple, ±1% 0.8V reference accuracy, thermal shutdown protection, and compatibility with ceramic output capacitors for compact, low-ripple dual-output designs.
Technical Context
The LT3506AIDHD#PBF implements a dual-channel current-mode buck architecture with shared master oscillator and independent slave oscillators synchronized in anti-phase (180°), minimizing input RMS ripple. Each channel features dedicated error amplifiers, VC pins for loop compensation or override, and open-collector PGOOD outputs valid above 3.4V VIN and when RUN/SS > 0.8V.
It uses internal bipolar NPN switches driven by BOOST pins (requiring external diode-capacitor charge pumps), supports duty cycles up to 78%, and incorporates frequency foldback during overload or short-circuit conditions-reducing switch current and thermal stress while maintaining regulation under fault conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.1MHz - enables use of sub-3μH inductors and <10μF ceramic output caps for ultra-compact layouts |
| Input Voltage Range | 3.6V to 25V - supports 4-cell Li-ion, 5V/12V/24V rails, wall adapters, and lead-acid batteries |
| Output Current per Channel | 1.6A continuous - sustained across full temperature range with proper thermal layout and inductor selection |
| Feedback Reference Voltage | 0.8V ±1% - ensures tight output regulation (±10mV) over –40°C to 125°C junction temperature |
| Power Good Threshold | 90% of regulated VOUT - provides reliable sequencing signal with 720mV FB rising threshold |
| Shutdown Current | 30μA max - minimizes system standby power when both RUN/SS pins are grounded |
| Thermal Shutdown | Active at TJ ≥ 125°C - protects device during overload or poor PCB heatsinking |
Pinout & Package
LT3506AIDHD#PBF is housed in a thermally enhanced 16-lead (5mm × 4mm) plastic DFN package with exposed pad (Pin 17) that must be soldered to PCB ground for electrical integrity and thermal performance (θJC = 4.3°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1 / FB2 (Pins 16, 9) | Feedback Input | Regulates output to 0.8V; connects to resistor divider tap - sets VOUT = 0.8V × (1 + R1/R2) |
| VC1 / VC2 (Pins 15, 10) | Error Amplifier Output | Controls peak switch current; used for loop compensation or forced shutdown when pulled to GND |
| RUN/SS1 / RUN/SS2 (Pins 13, 12) | Enable & Soft-Start Control | Pull to GND to disable channel; capacitor to GND limits inrush current during startup |
| PGOOD1 / PGOOD2 (Pins 14, 11) | Open-Collector Power-Good | Sinks current when output is out-of-regulation; requires external pull-up for logic-level signaling |
| BOOST1 / BOOST2 (Pins 1, 8) | Charge Pump Supply | Must be ≥1.5V above respective SW pin; driven via external diode+capacitor from VOUT or VIN |
| SW1 / SW2 (Pins 2, 7) | Switch Node | Connects to inductor, catch diode anode, and BOOST capacitor - carries high di/dt switching current |
| VIN1 (Pins 3, 4) / VIN2 (Pins 5, 6) | Input Power Supply | VIN1 powers internal bias regulator and Channel 1 switch; VIN2 powers Channel 2 switch only - may be tied together or isolated |
| Exposed Pad (Pin 17) | Ground & Thermal Path | Electrically GND and primary thermal conduction path - must be soldered to large PCB copper area |
Key Features
| Feature | Design Value |
|---|---|
| Anti-phase switching | Reduces input ripple current amplitude by ~50% vs. in-phase dual converters - lowers required input capacitance and EMI filter size |
| Independent soft-start control | Enables staggered power-up of dual rails to avoid inrush current stacking - critical for FPGA or multi-core processor supply sequencing |
| Frequency foldback under fault | Automatically reduces switching frequency to ~170kHz during overload - limits peak switch current and thermal dissipation without latch-off |
| Accurate 0.8V reference | ±1% tolerance over –40°C to 125°C - eliminates need for post-regulation trimming in industrial and telecom applications |
| Integrated 2A bipolar switches | Eliminates external MOSFETs and gate drivers - reduces BOM count and layout complexity while maintaining 1.6A continuous output capability |
Applications
| DSP Power Supplies | DSL Modems |
|---|---|
Use Scenario: Dual-rail power for TI C6000 or Analog Devices SHARC processors requiring 1.2V core and 3.3V I/O supplies. IC Role / Device Role / Timing Role: Primary DC/DC regulator providing tightly sequenced, low-noise, high-efficiency voltage conversion with independent enable control. Use Value: Anti-phase operation cuts input ripple, easing compliance with FCC Class B conducted emissions; PGOOD signals coordinate boot sequence with processor reset logic. |
Use Scenario: Compact, wide-input power solution for residential DSL modems operating from 12V wall adapters or PoE-derived 48V supplies. IC Role / Device Role / Timing Role: Dual-output buck controller generating 3.3V analog front-end and 1.8V digital PHY voltages from single input rail. Use Value: 1.1MHz operation allows use of 2.2μH inductors and 10μF X7R ceramics - achieving <0.5cm² footprint per channel in space-constrained modem PCBs. |
| Industrial Distributed Power | Hard Disk Drive Controllers |
Use Scenario: Local regulation of 5V or 12V distributed bus to generate 3.3V and 1.8V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: High-reliability dual buck regulator supporting extended temperature range (–40°C to 125°C) and robust fault handling. Use Value: Thermal shutdown and frequency foldback protect against sustained overloads in unventilated enclosures; wide VIN accommodates aging battery or unregulated transformer inputs. |
Use Scenario: Dual-voltage supply for HDD servo controller ASICs requiring fast transient response to head-positioning commands. IC Role / Device Role / Timing Role: Fast-current-mode regulator delivering 1.2V core and 2.5V interface rails with <10μs load-step recovery. Use Value: Current-mode control with cycle-by-cycle limiting ensures stable operation during rapid current transients caused by actuator coil activation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | Single-channel 3A buck; 3MHz switching; no integrated PGOOD or anti-phase capability | Requires two ICs for dual-rail design; higher frequency enables smaller passives but increases EMI sensitivity | Choose when higher efficiency at light loads or tighter output tolerance (±0.5%) is prioritized over integration and sequencing simplicity |
| TPS54290PWPR | Dual-channel 2A synchronous buck; 300kHz–2MHz adjustable frequency; no BOOST pin requirement | Uses integrated MOSFETs (no external diodes); lacks independent soft-start and anti-phase sync | Prefer when board space allows larger inductors and simplified external component count outweighs need for precise input ripple reduction |
Compared with LTC3631EMSE#PBF and TPS54290PWPR, the LT3506AIDHD#PBF uniquely delivers dual 1.6A outputs with anti-phase switching, integrated bipolar switches, and independent PGOOD/soft-start in a single 5mm × 4mm DFN - making it optimal for space-constrained, multi-rail systems requiring deterministic sequencing and minimal input filtering.
Availability
LT3506AIDHD#PBF is available at Aetrix Electronics and suitable for DSP power supplies, DSL modems, and industrial distributed power systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3506AIDHD#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, documentation, and manufacturing continuity for the LT® family of high-performance power management ICs.
The LT3506A belongs to Linear's monolithic dual buck regulator product line, designed specifically for compact, high-density multi-rail power conversion in telecom infrastructure, networking equipment, and industrial control systems where sequencing, thermal robustness, and wide input range are critical.
FAQ
What is the maximum junction temperature rating for the LT3506AIDHD#PBF?
The LT3506AIDHD#PBF has a maximum junction temperature (TJMAX) of 125°C and is specified for operation from –40°C to 125°C. Its DFN package features an exposed pad (Pin 17) that must be soldered to a thermal pad on the PCB to achieve the specified θJC of 4.3°C/W. Derating curves in the datasheet define safe operating area based on ambient temperature and airflow; exceeding TJMAX triggers thermal shutdown to protect the LT3506AIDHD#PBF.
Does the LT3506AIDHD#PBF require external Schottky diodes?
Yes, the LT3506AIDHD#PBF requires external Schottky diodes (e.g., MBR5230LT3) connected between each SW pin and output rail. Unlike synchronous buck regulators, it uses internal bipolar NPN switches and relies on external diodes for freewheeling current path. The diode forward voltage impacts efficiency and minimum on-time; typical design examples specify 0.4V VF diodes. The LT3506AIDHD#PBF datasheet explicitly references BAT-54A and MBR5230LT3 as validated components.
How does anti-phase switching reduce input ripple in the LT3506AIDHD#PBF?
The LT3506AIDHD#PBF synchronizes its two channels with 180° phase offset using a shared master oscillator. This causes input current pulses from each channel to cancel partially at the VIN node, reducing RMS and peak-to-peak input ripple current by up to 50% compared to in-phase operation. As a result, the LT3506AIDHD#PBF achieves lower input capacitor stress, smaller bulk capacitance requirements (e.g., 4.7μF ceramic), and relaxed EMI filtering - confirmed in typical application schematics and ripple measurement plots.
Can the LT3506AIDHD#PBF operate with only one channel enabled?
Yes, the LT3506AIDHD#PBF supports independent channel operation: grounding RUN/SS1 disables Channel 1 while Channel 2 remains active if RUN/SS2 is high, and vice versa. Both channels share the same internal reference and oscillator, so the enabled channel continues switching at 1.1MHz. The disabled channel draws only 30μA quiescent current, and its PGOOD output goes high-impedance. This flexibility allows dynamic rail scaling in systems like portable instrumentation where processing and analog sections power up separately.
What is the purpose of the BOOST pins on the LT3506AIDHD#PBF?
The BOOST1 and BOOST2 pins on the LT3506AIDHD#PBF provide gate drive voltage higher than VIN to fully saturate the internal bipolar NPN power switches - improving conduction efficiency and enabling reliable 1.6A output capability. Each BOOST pin must be biased ≥1.5V above its corresponding SW pin using an external diode and capacitor (e.g., 100nF ceramic). The LT3506AIDHD#PBF datasheet specifies BOOST current up to 30mA and mandates this external charge-pump network; omitting it causes excessive switch VCE(sat) and thermal failure.
LT3506AIDHD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFDFN 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):
- 22V
- Current - Output:
- 1.6A
- Frequency - Switching:
- 1.1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-DFN (5x4)
LT3506AIDHD#PBF FAQ
1.How can I place an order for LT3506AIDHD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3506AIDHD#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 LT3506AIDHD#PBF reliable?
The price and inventory of LT3506AIDHD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3506AIDHD#PBF is usually 5 days.
3.What payment methods are accepted for LT3506AIDHD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3506AIDHD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3506AIDHD#PBF?
LT3506AIDHD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3506AIDHD#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 LT3506AIDHD#PBF?
For technical support, including LT3506AIDHD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3506AIDHD#PBF requirements.
6.How does Aetrix verify that LT3506AIDHD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3506AIDHD#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 LT3506AIDHD#PBF meets industry standards.
7.What is the process for return or replacement of LT3506AIDHD#PBF?
All LT3506AIDHD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3506AIDHD#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 LT3506AIDHD#PBF part is unused and in its original packaging.
Return procedure for LT3506AIDHD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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