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Analog Devices Inc. LT1976BEFE#PBF
- Part No.:
- LT1976BEFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT1976BEFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.2A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,604
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Product details
Overview
LT1976BEFE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, current-mode step-down switching regulator IC designed for automotive and industrial power conversion. It operates from 3.3V to 60V input, delivers up to 1.5A peak switch current, features 1.6mA quiescent current (LT1976B variant), 200kHz fixed switching frequency, and integrates a 0.2Ω on-resistance NPN power switch. It is used in 14V/42V automotive systems requiring load dump protection and stable regulation under wide input transients.
For engineers reviewing the LT1976BEFE#PBF datasheet, LT1976BEFE#PBF pinout, LT1976BEFE#PBF application, or LT1976BEFE#PBF equivalent, key selection criteria include its 60V absolute maximum input rating, programmable Power Good flag with CT-based delay, Burst Mode–free operation (vs. LT1976), thermal shutdown, and compatibility with external synchronization - all critical for high-reliability 12V/24V/48V embedded power rails.
Technical Context
The LT1976BEFE#PBF implements a constant-frequency, current-mode control architecture with cycle-by-cycle peak current limiting and an internal 1.25V reference. Its error amplifier output (VC pin) directly sets the switch current threshold, enabling fast transient response and stable loop compensation across wide duty cycles.
Unlike the LT1976, the LT1976B variant disables Burst Mode operation - eliminating low-frequency output ripple at light loads by maintaining continuous pulse-skipping instead of deep-sleep bursts. This is achieved via a dedicated VC switching threshold (0.1V–0.8V) and absence of sleep-mode circuitry, trading ~1.5mA quiescent current for clean spectral performance in noise-sensitive applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.3V to 60V - supports direct connection to 42V automotive battery systems including load dump transients up to 60V. |
| Peak Switch Current | 1.2A (min), 2.5A (typ) - sustains full current limit across full duty cycle range, enabling robust short-circuit handling. |
| Quiescent Current | 1.6mA (typ) - fixed value for LT1976B; eliminates Burst Mode trade-offs, ensuring predictable light-load behavior without ripple modulation. |
| Switch On-Resistance | 0.2Ω (typ) - achieved via BOOST pin-driven saturation, reducing conduction loss comparable to low-Rds(on) MOSFETs. |
| Switching Frequency | 200kHz (±20kHz) - enables use of standard, cost-effective 33μH inductors while balancing EMI and efficiency. |
| Reference Voltage | 1.25V ±1.2% (–40°C to 125°C) - tight tolerance enables accurate output regulation across temperature for precision 3.3V/5V rails. |
| Power Good Flag | Programmable threshold (87–93% of VREF) with CT-based delay - allows configurable startup sequencing and fault detection timing. |
Pinout & Package
LT1976BEFE#PBF is housed in a 16-pin thermally enhanced TSSOP package with exposed pad (pin 17), requiring soldering to PCB ground plane for thermal management (θJC = 10°C/W). Pins 1, 3, and 5 are no-connect (NC) and electrically isolated.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 2) | Switch emitter node | Connects to inductor; driven to VIN during on-time; requires Schottky catch diode to clamp negative flyback voltage. |
| VIN (Pin 4) | Power switch collector & primary supply | Supplies internal circuitry when BIAS is unconnected; must be decoupled with low-ESR ceramic capacitor near pin. |
| BOOST (Pin 6) | Switch driver boost supply | Accepts voltage ≥VIN + 3.3V; enables full saturation of internal NPN switch, minimizing VCE(sat) to ~0.2Ω-equivalent loss. |
| CT (Pin 7) | Power Good delay timing | Current source/sink node; external capacitor sets PG assertion delay (t = CCT × VCT / ICT); clamped at 1.2V. |
| GND (Pins 8, 17) | Signal & thermal reference | Exposed pad (pin 17) must be soldered to large copper area for thermal dissipation and low-noise feedback reference. |
| CSS (Pin 9) | Soft-start ramp control | Current threshold (~13μA typ) limits output voltage slew rate; disabled above FB = 0.9V to prevent interference during regulation. |
| BIAS (Pin 10) | Efficiency-boost auxiliary supply | When tied to regulated output (≥3V), powers internal circuitry from VOUT instead of VIN, improving efficiency at high VIN/VOUT ratios. |
| VC (Pin 11) | Error amplifier output & current limit setpoint | Directly controls peak switch current; 0.45V (light load) to 2.2V (current limit); usable for external loop compensation or override. |
| FB (Pin 12) | Feedback sensing input | Monitors resistive divider output; 1.25V reference enables precise VOUT setting; triggers frequency foldback below 0.9V for overload protection. |
| PGFB (Pin 13) | Power Good comparator input | Compares against internal 90% VREF threshold; initiates CT charging when exceeded, enabling programmable PG assertion delay. |
| SYNC (Pin 14) | External oscillator synchronization | Logic-level compatible (1.5–2.0V min); accepts 230–600kHz external clock; disabled when FB < 0.9V. |
| SHDN (Pin 15) | Enable/disable control | Active-high; 1.3V threshold; draws only 5–20μA; reduces total supply current to <1μA in shutdown. |
| PG (Pin 16) | Power Good open-drain output | Active-low signal (200μA sink) indicating valid output; high-impedance when CT clamp is active (i.e., after PG delay). |
Key Features
| Feature | Design Value |
|---|---|
| Load dump protection to 60V | Withstands ISO 7637-2 Pulse 5a transients without derating or external clamping, simplifying front-end protection design. |
| Programmable Power Good flag | Configurable delay (via CT capacitor) and threshold (via PGFB resistor divider) enable precise system power sequencing and fault reporting. |
| Saturating switch design (0.2Ω) | Reduces conduction losses at high current vs. non-saturated bipolar switches, enabling >90% efficiency at 1A with 12V→3.3V conversion. |
| Thermally enhanced TSSOP-16EP | Exposed pad lowers junction-to-board thermal resistance to 10°C/W, supporting 1.5A continuous output without heatsink in 4-layer PCB layouts. |
| Easily synchronizable oscillator | Accepts external clock up to 600kHz with no phase lock loop required, enabling EMI reduction via spread-spectrum or fixed-frequency coordination. |
| Soft-start via single CSS capacitor | Controls output voltage ramp rate to limit inrush current and prevent overshoot; threshold scales with FB voltage for adaptive startup behavior. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC I/O Power Supply |
|---|---|
Use Scenario: Regulating 12V battery input to stable 3.3V for microcontroller, CAN transceiver, and sensor interface circuits in harsh vehicle environments. IC Role / Device Role / Timing Role: Primary step-down DC/DC converter providing isolated, ripple-controlled 3.3V rail with load dump immunity and thermal shutdown. Use Value: Eliminates need for external TVS or pre-regulator stages; 60V absolute max rating handles cold-crank and jump-start transients without failure. |
Use Scenario: Generating 5V/1A power for digital I/O modules in programmable logic controllers operating from 24V or 48V factory bus supplies. IC Role / Device Role / Timing Role: High-efficiency buck regulator delivering tightly regulated output with programmable Power Good signaling for system health monitoring. Use Value: Enables deterministic startup sequencing and fault isolation via CT-configurable PG delay, improving system-level diagnostics and uptime. |
| Distributed Telecom Power System | Battery-Powered Test Equipment |
Use Scenario: Converting 48V backplane voltage to 5V for FPGA configuration and peripheral logic in compact telecom line cards. IC Role / Device Role / Timing Role: Fixed-frequency current-mode buck converter synchronized to system clock to minimize conducted EMI in dense board layouts. Use Value: 200kHz switching allows use of small, shielded 33μH inductors while maintaining >88% efficiency at full load, reducing board area and thermal footprint. |
Use Scenario: Powering portable handheld test instruments with Li-ion battery input (3.3V–4.2V) and requirement for ultra-clean 3.3V analog supply. IC Role / Device Role / Timing Role: Low-noise buck regulator operating in pulse-skipping mode (LT1976B) to avoid audible switching artifacts and low-frequency ripple in sensitive analog sections. Use Value: Absence of Burst Mode ensures consistent 200kHz fundamental frequency, simplifying filtering and preventing beat frequencies with ADC sampling clocks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | 40V max input, 1.5A, 3mm × 4mm MSOP, integrated MOSFETs, 3.5μA IQ | Lower voltage rating; better light-load efficiency but no 60V load dump support | Select for space-constrained 24V systems where ultra-low IQ outweighs transient robustness. |
| LM5164QDDARQ1 | 65V max input, 1A, automotive AEC-Q100 Grade 1, 100μA IQ, integrated high-side FET | Lower current rating; includes integrated gate driver and fault reporting, but lacks programmable PG delay | Select for ASIL-B automotive applications requiring qualification and built-in diagnostics over custom PG timing. |
Compared with LTC3631EMSE#PBF and LM5164QDDARQ1, the LT1976BEFE#PBF uniquely balances 60V transient tolerance, 1.5A capability, and programmable Power Good timing - making it optimal for industrial and legacy automotive designs where reliability under extreme voltage stress is prioritized over minimum quiescent current or AEC-Q100 certification.
Availability
LT1976BEFE#PBF is available at Aetrix Electronics and suitable for 14V/42V automotive systems, industrial PLC power supplies, and distributed telecom power conversion requiring stable component supply with long-term lifecycle support.
Supply support for LT1976BEFE#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 technical and manufacturing continuity for the LT product family, known for high-performance analog and power management ICs targeting demanding industrial and automotive applications.
The LT1976/LT1976B series was designed specifically for high-input-voltage DC/DC conversion in automotive and industrial environments - emphasizing robustness against load dump, wide temperature operation (–40°C to 125°C), and predictable light-load behavior without Burst Mode artifacts.
FAQ
What is the maximum input voltage rating for the LT1976BEFE#PBF?
The LT1976BEFE#PBF has an absolute maximum input voltage rating of 60V on the VIN pin, enabling direct integration into 42V automotive systems and compatibility with ISO 7637-2 load dump transients. Continuous operation is specified from 3.3V to 60V, with guaranteed performance across –40°C to 125°C junction temperature.
How does the LT1976BEFE#PBF differ from the LT1976EFE#PBF?
The LT1976BEFE#PBF disables Burst Mode operation present in the LT1976EFE#PBF, instead using pulse-skipping at light loads to eliminate low-frequency output ripple. This results in higher quiescent current (1.6mA vs. 100μA) but cleaner spectral performance - a deliberate trade-off for noise-sensitive analog or RF subsystems powered by the LT1976BEFE#PBF.
Can the LT1976BEFE#PBF be synchronized to an external clock?
Yes, the LT1976BEFE#PBF supports external synchronization via the SYNC pin (Pin 14), accepting logic-level inputs from 230kHz to 600kHz with 20–80% duty cycle. Synchronization is disabled when the FB pin voltage falls below 0.9V, such as during startup or overload conditions - ensuring reliable operation during fault recovery.
What is the purpose of the BOOST pin on the LT1976BEFE#PBF?
The BOOST pin on the LT1976BEFE#PBF provides a boosted gate drive voltage (≥VIN + 3.3V) to fully saturate the internal NPN power switch, reducing its effective on-resistance to 0.2Ω. This is implemented using an external bootstrap capacitor and Schottky diode, enabling high efficiency comparable to MOSFET-based regulators without requiring external high-side drivers.
Does the LT1976BEFE#PBF require the exposed pad to be connected to ground?
Yes, the exposed pad (Pin 17) of the LT1976BEFE#PBF must be soldered to the PCB ground plane. It serves as both the thermal path (θJC = 10°C/W) and the signal ground reference for the internal circuitry. Failure to connect it compromises thermal performance, output regulation accuracy, and noise immunity - especially critical for stable operation at full 1.5A load.
LT1976BEFE#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:
- 1
- Voltage - Input (Min):
- 3.3V
- Voltage - Input (Max):
- 60V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 55.2V
- Current - Output:
- 1.2A (Switch)
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT1976BEFE#PBF FAQ
1.How can I place an order for LT1976BEFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1976BEFE#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 LT1976BEFE#PBF reliable?
The price and inventory of LT1976BEFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1976BEFE#PBF is usually 5 days.
3.What payment methods are accepted for LT1976BEFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1976BEFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1976BEFE#PBF?
LT1976BEFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1976BEFE#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 LT1976BEFE#PBF?
For technical support, including LT1976BEFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1976BEFE#PBF requirements.
6.How does Aetrix verify that LT1976BEFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT1976BEFE#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 LT1976BEFE#PBF meets industry standards.
7.What is the process for return or replacement of LT1976BEFE#PBF?
All LT1976BEFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1976BEFE#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 LT1976BEFE#PBF part is unused and in its original packaging.
Return procedure for LT1976BEFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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