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Analog Devices Inc. LT1976HFE#PBF
- Part No.:
- LT1976HFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT1976HFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.5A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:175
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Product details
Overview
LT1976HFE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, current-mode synchronous 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 100μA quiescent current in Burst Mode, 200kHz fixed switching frequency, and integrates a 0.2Ω 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 LT1976HFE#PBF datasheet, LT1976HFE#PBF pinout, LT1976HFE#PBF application, or LT1976HFE#PBF equivalent, key selection considerations include its –40°C to 140°C junction temperature rating, programmable Power Good flag with CT-based delay, soft-start via CSS pin, and BOOST-driven saturation architecture enabling low conduction loss at high VIN.
Technical Context
The LT1976HFE#PBF implements constant-frequency current-mode control with an internal 200kHz oscillator, dual-loop feedback (voltage error amplifier + cycle-by-cycle peak current sensing), and patented circuitry maintaining peak switch current across full duty cycle range. Its NPN switch uses external BOOST capacitor/diode to achieve ~0.2Ω effective on-resistance at high input voltages.
It supports Burst Mode operation (LT1976 variant) for ultra-low 100μA no-load IQ, with BIAS pin biasing capability to improve efficiency at high VIN/light loads. The device includes thermal shutdown, undervoltage lockout, and programmable Power Good with adjustable threshold (via PGFB divider) and delay (via CT capacitor).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.3V to 60V - supports direct connection to 42V automotive battery rails and withstands load dump transients up to 60V. |
| Peak Switch Current | 1.5A - enables ≥1A continuous output current with margin for transient loads in compact 16-pin TSSOP package. |
| Quiescent Current | 100μA (Burst Mode) - sustains >1000-hour battery life in always-on automotive modules (e.g., telematics, ADAS sensors). |
| Switch On-Resistance | 0.2Ω (typ.) - achieved via BOOST pin drive; reduces conduction loss by >50% vs. non-boosted bipolar switches at 12V–48V inputs. |
| Feedback Reference | 1.25V ±1.2% - enables precise output voltage setting (e.g., 3.3V, 5V, 12V) with standard resistor dividers; FB pin bias current ≤200nA minimizes divider error. |
| Operating Junction Temp | –40°C to 140°C - qualified for under-hood automotive applications per AEC-Q100 stress test conditions. |
| Power Good Flag | Programmable threshold (87–93% of VREF) and delay (via CT capacitor) - provides configurable system-level power sequencing and fault detection. |
Pinout & Package
LT1976HFE#PBF is housed in a 16-pin thermally enhanced TSSOP package with exposed pad (Pin 17 = GND), optimized for low θJA = 45°C/W and 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 |
|---|---|---|
| SW (Pin 2) | Switch emitter node | Connects to inductor and catch diode cathode; swings from –0.3V (clamped) to VIN during operation; requires low-inductance layout. |
| VIN (Pin 4) | Power switch collector & primary supply | Supplies internal circuitry when BIAS is unconnected; carries high di/dt; must be decoupled with low-ESR ceramic capacitor near pin. |
| BOOST (Pin 6) | Switch driver boost supply | Accepts voltage ≥VIN + 3.3V via external capacitor/diode; enables full saturation of NPN switch, reducing VCE(SAT) to ~0.3V at 1.5A. |
| CT (Pin 7) | Power Good delay timing | Current source/sink node controlling PG flag delay time (t = CCT × VCT/ICT); clamps at 1.2V to assert PG high-impedance state. |
| GND (Pins 8, 17) | Signal & thermal reference | Pin 17 is exposed pad - must be soldered to large copper area for thermal dissipation and noise immunity; forms return path for FB, PGFB, and load. |
| CSS (Pin 9) | Soft-start ramp control | Sinks current into external capacitor to limit dVOUT/dt at startup; threshold scales with FB voltage; disabled above 0.9V FB. |
| BIAS (Pin 10) | Efficiency-optimized bias supply | When connected to VOUT ≥3V, powers internal circuitry from output instead of VIN, improving light-load efficiency by >15% at VIN = 48V. |
| VC (Pin 11) | Error amplifier output / current limit input | Provides loop compensation node; voltage ranges from ~0.45V (light load) to 2.2V (current limit); can be overridden for external control or disable. |
| FB (Pin 12) | Output voltage sense input | Compares resistive divider output to 1.25V reference; below 0.9V disables SYNC and enables frequency foldback/soft-start. |
| PGFB (Pin 13) | Power Good comparator input | Resistive divider from VOUT or VIN sets PG activation threshold (87–93% of VREF); rising edge initiates CT charging and PG assertion delay. |
| SYNC (Pin 14) | External clock synchronization | Accepts 230–600kHz logic-level signal (20–80% duty) to align switching frequency; disabled when FB < 0.9V. |
| SHDN (Pin 15) | Enable/disable control | Logic-high (>1.3V) enables regulator; draws only 5–20μA; pulls IQ < 1μA in shutdown - critical for battery-backed systems. |
| PG (Pin 16) | Power Good open-drain output | Active-low (200μA sink) when VPGFB < threshold and CT clamp inactive; high-impedance when CT clamped - signals valid VOUT. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode Operation | Reduces no-load IQ to 100μA by disabling switching and bias circuitry during light loads - extends battery runtime without compromising regulation accuracy. |
| Load Dump Protection | Withstands 60V transients on VIN per ISO 7637-2 Pulse 5a - eliminates need for upstream TVS in 12V/24V/42V automotive designs. |
| Programmable Power Good | Configurable VOUT monitor threshold (via PGFB divider) and delay (via CT capacitor) enables robust power sequencing in multi-rail systems. |
| BOOST-Driven Saturation | External BOOST capacitor/diode elevates switch base drive, achieving 0.2Ω effective RON - cuts conduction loss by 40–60% vs. standard bipolar regulators at 24V–48V inputs. |
| Thermally Enhanced TSSOP | 16-pin package with exposed GND pad (Pin 17) enables θJC = 10°C/W - supports 1.5A operation at 140°C junction temperature without heatsink. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC I/O Power Supply |
|---|---|
Use Scenario: Powering microcontroller, CAN transceiver, and sensor interfaces in under-hood BCM units exposed to 42V load dump and –40°C to 125°C ambient. IC Role / Device Role / Timing Role: Primary 3.3V/5V buck regulator providing regulated rail with programmable Power Good for MCU reset coordination and fault reporting. Use Value: 140°C-rated operation ensures reliability without derating; 100μA Burst Mode IQ enables >5-year battery backup for keep-alive functions. |
Use Scenario: Generating isolated 5V/12V rails for analog input modules and digital outputs in DIN-rail mounted PLCs operating in 0–60°C industrial enclosures. IC Role / Device Role / Timing Role: High-efficiency step-down converter accepting wide-range 24VDC factory bus input (18–36V) while delivering stable output under variable load. Use Value: 60V absolute max rating allows safe operation during 36V bus surges; BOOST architecture maintains >88% efficiency at 24V→5V/1A. |
| Telecom Remote Radio Unit (RRU) | EV Battery Management System (BMS) Sensor Node |
Use Scenario: Powering FPGA, ADCs, and RF front-end bias supplies in outdoor telecom RRUs subject to wide temperature swings and lightning-induced transients. IC Role / Device Role / Timing Role: Input-stage buck converter stepping down 48V PoE++ or DC plant voltage to intermediate 12V/5V rails with EMI-controlled 200kHz switching. Use Value: Synchronizable switching frequency avoids interference with sensitive RF bands; soft-start (CSS) prevents inrush current tripping upstream breakers. |
Use Scenario: Supplying isolated sensor signal conditioning circuits and isolated CAN in battery pack monitoring units located near high-voltage traction batteries. IC Role / Device Role / Timing Role: High-reliability 3.3V regulator powered from 12V auxiliary battery, featuring load dump tolerance and thermal shutdown for safety-critical BMS nodes. Use Value: –40°C to 140°C qualification meets ASIL-B requirements; PG flag provides diagnostic feedback to main BMS controller during brownout events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3642EMSE#PBF | 40V max input, 2A output, 3MHz switching, integrated MOSFETs; no BOOST pin required; 2.5μA IQ in sleep mode. | Better suited for space-constrained, high-density layouts where 200kHz EMI filtering is impractical; lacks 60V load dump rating. | Select LTC3642EMSE#PBF when board area is limited and input voltage stays ≤40V; avoid for automotive front-end or 42V battery direct connection. |
| LM5164QPWPRQ1 | 65V max input, 1A output, 100kHz–2.2MHz sync'able, integrated high-side FET; 14μA IQ; AEC-Q100 Grade 1. | Higher integration (no external BOOST diode/cap) but lower peak current; optimized for cost-sensitive automotive infotainment rather than under-hood. | Select LM5164QPWPRQ1 for AEC-Q100-compliant 1A applications with tighter cost targets; retain LT1976HFE#PBF for 1.5A+ and 140°C under-hood use. |
Compared with LTC3642EMSE#PBF and LM5164QPWPRQ1, the LT1976HFE#PBF uniquely combines 60V load dump tolerance, 1.5A peak current, –40°C to 140°C operation, and BOOST-enabled low-loss bipolar switching - making it irreplaceable for high-reliability automotive power stages where thermal margin and transient robustness are non-negotiable.
Availability
LT1976HFE#PBF is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC power supplies, and telecom remote radio units requiring stable component supply across extended temperature and high-voltage stress conditions.
Supply support for LT1976HFE#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving automotive, industrial, communications, and healthcare markets.
The LT1976HFE#PBF belongs to Linear's high-voltage monolithic buck regulator product line, engineered specifically for automotive and industrial environments demanding wide input range, load dump resilience, and extended temperature operation without external complexity.
FAQ
What is the maximum allowable input voltage for LT1976HFE#PBF, and how does it handle automotive load dump events?
The LT1976HFE#PBF has an absolute maximum input voltage rating of 60V and is explicitly designed to withstand ISO 7637-2 Pulse 5a load dump transients up to that level without damage or regulation loss. Its internal circuitry remains functional during these events due to robust input stage design and integrated protection features - no external TVS diode is required for compliance in 12V/24V/42V automotive systems.
Does LT1976HFE#PBF support synchronization to an external clock, and what is its valid frequency range?
Yes, LT1976HFE#PBF supports external synchronization via the SYNC pin (Pin 14). It accepts logic-level input signals with 20–80% duty cycle across a 230kHz to 600kHz range. Synchronization is disabled when the FB pin voltage falls below 0.9V, such as during startup or fault conditions - ensuring reliable operation during soft-start and fault recovery sequences.
How does the BOOST pin function in LT1976HFE#PBF, and what external components are required?
The BOOST pin (Pin 6) provides elevated base drive to the internal NPN power switch using an external bootstrap capacitor and Schottky diode (e.g., Diodes Inc. B1100). This configuration forces the switch into deep saturation, achieving an effective on-resistance of 0.2Ω - significantly reducing conduction losses compared to non-boosted architectures, especially at input voltages above 24V.
What is the purpose of the CSS pin on LT1976HFE#PBF, and how is soft-start configured?
The CSS pin (Pin 9) controls soft-start by sinking current into an external capacitor connected to the output rail. When CSS current exceeds its threshold (~7–20μA, scaling with FB voltage), the output voltage ramp rate is limited. A typical 10nF capacitor yields ~10ms startup time. Soft-start is automatically disabled once FB exceeds 0.9V, preventing unintended activation during normal regulation.
Is LT1976HFE#PBF pin-compatible with other variants in the LT1976 family, such as LT1976BEFE#PBF?
Yes, LT1976HFE#PBF shares identical pinout, package (16-pin TSSOP with exposed pad), and footprint with all LT1976/LT1976B variants including LT1976BEFE#PBF. However, functional differences exist: LT1976HFE#PBF operates in Burst Mode (100μA IQ), while LT1976BEFE#PBF uses pulse-skipping (1.6mA IQ) to eliminate low-frequency ripple - requiring separate layout validation for noise-sensitive applications.
LT1976HFE#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:
- 1.5A (Switch)
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT1976HFE#PBF FAQ
1.How can I place an order for LT1976HFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1976HFE#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 LT1976HFE#PBF reliable?
The price and inventory of LT1976HFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1976HFE#PBF is usually 5 days.
3.What payment methods are accepted for LT1976HFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1976HFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1976HFE#PBF?
LT1976HFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1976HFE#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 LT1976HFE#PBF?
For technical support, including LT1976HFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1976HFE#PBF requirements.
6.How does Aetrix verify that LT1976HFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT1976HFE#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 LT1976HFE#PBF meets industry standards.
7.What is the process for return or replacement of LT1976HFE#PBF?
All LT1976HFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1976HFE#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 LT1976HFE#PBF part is unused and in its original packaging.
Return procedure for LT1976HFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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