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Analog Devices Inc. LT3514HFE#PBF
- Part No.:
- LT3514HFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- -
- Datasheet:
-
LT3514HFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 24TSSOP
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Inventory:4,937
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Product details
Overview
LT3514HFE#PBF from Analog Devices (formerly Linear Technology) is a triple-output monolithic step-down switching regulator IC with 2A/1A/1A output capability, wide 3.2V–36V input range, and integrated boost regulator enabling true 100% duty cycle operation. It features independent soft-start pins, output voltage tracking, programmable frequency (350kHz–2.2MHz), and power-good indication - deployed in automotive battery regulation and industrial distributed power systems.
For engineers reviewing the LT3514HFE#PBF datasheet, LT3514HFE#PBF pinout, LT3514HFE#PBF application, or LT3514HFE#PBF equivalent, key selection considerations include thermal performance at 150°C junction rating, TSSOP-24 package footprint compatibility, channel-specific current limits (SW3: 3.5A typ, SW1/SW4: 1.75A typ), and SKY pin drive voltage regulation to 4.85V above VIN.
Technical Context
The LT3514HFE#PBF integrates three synchronous buck regulators (CH1: 1A, CH3: 2A, CH4: 1A) and one dedicated boost regulator (CH5) driving the SKY rail. Its antiphase clocking reduces input ripple, while internal slope compensation and dual current-limit sensing (switch + catch diode) ensure robust overload protection across all channels.
Operation relies on precise SKY voltage regulation (4.85V above VIN) to fully saturate bipolar power switches; SKY must be decoupled with ≥1µF to VIN. The device supports external synchronization and resistor-programmed constant-frequency operation, with minimum on-time of 110ns (at 125°C) defining pulse-skipping boundaries.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.2V to 36V (40V transient); enables direct connection to 12V/24V automotive and industrial rails without pre-regulation. |
| Output Current Capability | CH1: 1A, CH3: 2A, CH4: 1A - allows single-chip supply for mixed-voltage SoC subsystems (e.g., 1.8V core, 3.3V I/O, 5V peripheral). |
| Switching Frequency Range | 350kHz to 2.2MHz (programmable via RT resistor or SYNC signal); supports compact magnetics and EMI optimization. |
| Feedback Reference Voltage | 800mV ±10mV (over temp); enables accurate output programming with standard resistor dividers (e.g., R2 = 10.2kΩ). |
| Thermal Rating | Junction temperature range: –40°C to +150°C; validated for under-hood automotive and high-ambient industrial environments. |
| Power Good Threshold | 710mV rising threshold per FB pin; ensures all outputs are within regulation before system enable. |
| SKY Drive Voltage | 4.85V above VIN (regulated); provides sufficient gate drive headroom for bipolar switch saturation across full input range. |
Pinout & Package
LT3514HFE#PBF is housed in a 24-lead plastic TSSOP package (FE) with exposed thermal pad (Pin 25 = GND). The package delivers θJA = 33°C/W and requires soldering of the exposed pad to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pins 1, 11, 12) | Main input power supply | Supplies current to internal regulators and power switches; must be locally bypassed and tied to common source. |
| GND (Pin 22, Exposed Pad 25) | Ground reference and thermal path | Primary return for all circuits; exposed pad must be soldered to large PCB ground plane with thermal vias. |
| SW1, SW3, SW4 (Pins 4, 5, 6, 8) | Power switch outputs | Drive external inductors and Schottky diodes; SW3 supports 2A continuous load (3.5A current limit). |
| DA1, DA3, DA4 (Pins 3, 7, 9) | Catch diode anode sense inputs | Enable diode-current limiting to prevent inductor current runaway during transients. |
| FB1, FB3, FB4 (Pins 18, 19, 20) | Output voltage feedback inputs | Each regulated to 800mV; used with resistor dividers to set 1.8V/3.3V/5V outputs. |
| RUN/SS1, RUN/SS3, RUN/SS4 (Pins 13, 14, 15) | Channel enable & soft-start control | Internal 1.3µA current source ramps voltage; pull below 0.1V to shut down individual channel. |
| EN/UVLO (Pin 16) | Global enable and input UVLO | 1.44V rising threshold; also functions as accurate undervoltage lockout (2.9V typical) for input rail monitoring. |
| RT/SYNC (Pin 17) | Frequency programming / sync input | Accepts resistor-to-GND (350kHz–2.2MHz) or external clock (350kHz–2.2MHz, >50ns pulse width). |
| PG (Pin 21) | Open-collector power-good output | Asserts low until all FB pins exceed 710mV; requires external pull-up for system sequencing. |
| SW5 (Pin 23) | Boost regulator switch output | Drives external inductor to generate SKY rail; peak current limited to 320mA. |
| SKY (Pin 24) | Boost regulator output (diode anode) | Provides 4.85V above VIN to drive buck switch bases; must be decoupled with ≥1µF to VIN. |
Key Features
| Feature | Design Value |
|---|---|
| Triple independent buck regulation | Enables single-package solution for multi-rail systems (e.g., 1.8V/3.3V/5V) with channel-specific soft-start and shutdown. |
| 100% duty cycle support | On-chip boost regulator maintains SKY ≥ 4.85V above VIN, allowing regulation even when VIN ≈ VOUT. |
| Anti-phase switching | Reduces input capacitor RMS current and total input ripple by staggering CH3/CH4 relative to CH1. |
| Robust fault protection | Cycle-by-cycle switch current limit + catch diode current limit + thermal shutdown prevent damage during overload or short-circuit. |
| Programmable UVLO and tracking | EN/UVLO threshold adjustable via resistor divider; RUN/SS pins allow precise output voltage sequencing and tracking. |
Applications
| Automotive Battery Regulation | Industrial Control Supplies |
|---|---|
|
Use Scenario: Regulating 12V/24V vehicle battery to 1.8V (ECU core), 3.3V (CAN transceiver), and 5V (sensor interface) in engine control units. IC Role / Device Role / Timing Role: Triple-output DC/DC converter providing isolated, sequenced, and tracked power rails with automotive-grade thermal margin (150°C). Use Value: Eliminates need for three discrete regulators; SKY-based 100% duty cycle ensures stable 3.3V output during cold-crank (6V battery dip). |
Use Scenario: Powering PLC I/O modules requiring tightly regulated 5V, 3.3V, and 1.8V rails from 24V industrial bus. IC Role / Device Role / Timing Role: Centralized power management IC delivering independent soft-start, power-good signaling, and fault isolation per rail. Use Value: Independent RUN/SS pins enable controlled power-up sequence to prevent backfeeding; PG pin coordinates system reset timing. |
| Wall Transformer Regulation | Distributed Supply Regulation |
|
Use Scenario: Converting 9–24V AC/DC wall adapter output to 5V USB, 3.3V MCU, and 1.8V FPGA core in embedded gateways. IC Role / Device Role / Timing Role: High-efficiency buck controller supporting wide-input, variable-load conditions with minimal external components. Use Value: Internal compensation and 800mV FB reference reduce BOM count; 2.2MHz sync capability enables ultra-small inductors (<1µH). |
Use Scenario: Local point-of-load regulation in telecom line cards where 48V backplane supplies multiple sub-systems. IC Role / Device Role / Timing Role: Compact triple-buck regulator operating up to 36V input, with thermal robustness for convection-cooled chassis. Use Value: TSSOP-24 package fits dense layouts; 33°C/W θJA enables >1.5W dissipation without forced air in 70°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3646EFE#PBF | Single 4A buck with integrated MOSFETs; no multi-channel or SKY boost; higher efficiency but no 100% DC capability. | Best for single-rail high-current loads; lacks independent sequencing and triple-output flexibility. | Select when only one output is needed and board space is constrained; not suitable for multi-rail tracking. |
| LT3504IFE#PBF | Four 1A buck channels in same TSSOP-24; no CH3 2A capability; pin-compatible but different channel mapping. | Requires redesign of feedback and soft-start networks; cannot replace CH3 2A requirement without derating. | Choose only if 2A output is unnecessary and four lower-current rails are preferred; verify RUN/SS pin assignment. |
Compared with LTC3646EFE#PBF and LT3504IFE#PBF, the LT3514HFE#PBF uniquely delivers asymmetric 2A/1A/1A outputs with integrated 100% duty cycle support in a thermally enhanced TSSOP, making it optimal for cost-sensitive, space-constrained multi-rail designs requiring automotive-grade reliability.
Availability
LT3514HFE#PBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial control supplies, and distributed supply regulation requiring stable component supply across extended temperature ranges.
Supply support for LT3514HFE#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3514 product line was designed specifically for high-reliability, multi-rail DC/DC conversion in automotive and industrial environments - emphasizing thermal robustness, fault resilience, and minimal external component count.
FAQ
What is the maximum junction temperature rating for LT3514HFE#PBF?
The LT3514HFE#PBF is rated for operation from –40°C to +150°C junction temperature, distinguishing it from the E- and I-grade variants (–40°C to +125°C). This extended rating is validated per manufacturer specifications and supports under-hood automotive and high-ambient industrial deployments where sustained thermal stress occurs.
How does the SKY pin function in LT3514HFE#PBF, and what external components are required?
The SKY pin in LT3514HFE#PBF is the output of the internal Schottky diode in the boost regulator (CH5), delivering a regulated voltage 4.85V above VIN to drive the bipolar power switches. It requires a minimum 1µF ceramic capacitor connected directly between SKY and VIN; an external inductor (e.g., 8.2µH at 1MHz) must also connect SW5 to VIN to complete the boost circuit.
Can LT3514HFE#PBF operate with input voltage equal to the output voltage?
Yes - the LT3514HFE#PBF supports true 100% duty cycle operation via its integrated boost regulator, which generates the SKY voltage 4.85V above VIN. This ensures sufficient gate drive headroom to fully saturate the internal bipolar switches even when VIN ≈ VOUT, such as regulating 5V out from a 5.5V input during brownout conditions.
What are the current limit specifications for each switch in LT3514HFE#PBF?
Per the datasheet, LT3514HFE#PBF specifies switch current limits of 3.5A (typ) for SW3 (2A channel), and 1.75A (typ) for SW1 and SW4 (1A channels). These are cycle-by-cycle peak limits, with additional catch diode current limiting (2.0A/2.5A for SW3, 1.15A/1.45A for SW1/SW4 at FB = 0.7V) to prevent inductor current runaway during transients.
Is LT3514HFE#PBF pin-compatible with other members of the LT35xx family?
The LT3514HFE#PBF shares the same 24-lead TSSOP (FE) package and pinout as LT3514EFE#PBF and LT3514IFE#PBF, and is pin-compatible with LT3504 in TSSOP - though LT3504 has four 1A channels versus LT3514's 2A/1A/1A configuration. No PCB changes are required when upgrading from E/IFE grades, but functional validation is needed when replacing LT3504 due to missing CH2 and merged CH3 current capability.
LT3514HFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- *
- Package/Case:
- -
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- -
- Output Configuration:
- -
- Topology:
- -
- Output Type:
- -
- Number of Outputs:
- -
- Voltage - Input (Min):
- -
- Voltage - Input (Max):
- -
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- -
- Frequency - Switching:
- -
- Synchronous Rectifier:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
LT3514HFE#PBF FAQ
1.How can I place an order for LT3514HFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3514HFE#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 LT3514HFE#PBF reliable?
The price and inventory of LT3514HFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3514HFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3514HFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3514HFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3514HFE#PBF?
LT3514HFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3514HFE#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 LT3514HFE#PBF?
For technical support, including LT3514HFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3514HFE#PBF requirements.
6.How does Aetrix verify that LT3514HFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3514HFE#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 LT3514HFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3514HFE#PBF?
All LT3514HFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3514HFE#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 LT3514HFE#PBF part is unused and in its original packaging.
Return procedure for LT3514HFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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