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Analog Devices Inc. LT1977EFE#TRPBF
- Part No.:
- LT1977EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT1977EFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1.5A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,783
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Product details
Overview
LT1977EFE#TRPBF from Analog Devices (formerly Linear Technology) is a high-voltage, current-mode synchronous step-down switching regulator IC designed for automotive and industrial power systems. It operates from 3.3V to 60V input, delivers up to 1.5A peak switch current with 0.2Ω on-resistance, supports 500kHz fixed-frequency operation, and features Burst Mode® for 100µA no-load quiescent current - enabling reliable 14V/42V automotive battery-powered regulation.
For engineers reviewing the LT1977EFE#TRPBF datasheet, LT1977EFE#TRPBF pinout, LT1977EFE#TRPBF application, or LT1977EFE#TRPBF equivalent, key selection considerations include its 16-pin TSSOP thermally enhanced package with exposed pad, programmable Power Good flag, soft-start via CSS pin, load dump protection to 60V, and compatibility with external synchronization up to 700kHz.
Technical Context
The LT1977EFE#TRPBF implements constant-frequency current-mode control with an internal 500kHz oscillator, dual feedback loops (error amplifier + cycle-by-cycle current sense), and patented peak switch current maintenance across full duty cycle range (15%–90%). Its architecture uses a BOOST pin-driven saturated NPN switch and BIAS pin-assisted efficiency optimization at high VIN/light loads.
It integrates Burst Mode® operation with 45µA sleep current, programmable PGFB threshold (88%–92% of 1.25V reference), CT-based delay timing, and thermal shutdown. The VC pin serves as both error amplifier output and current comparator input, enabling direct loop override or current clamping - critical for transient response and short-circuit foldback.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.3V to 60V - supports cold-crank (4.5V) and load-dump (60V) conditions in 12V/24V/42V automotive systems. |
| Switch Current Limit | 1.5A (min), 2.4A (typ) - ensures robust overcurrent protection while maintaining regulation under full duty cycle. |
| Quiescent Current | 100µA in Burst Mode - enables >10-year battery life in always-on vehicle modules (e.g., telematics, CAN gateways). |
| Feedback Reference | 1.25V ±2.5% - allows precise output voltage setting (e.g., 3.3V, 5V, 12V) using standard 1% resistor dividers. |
| Switch On-Resistance | 0.2Ω (max) - reduces conduction loss and thermal stress at 1.5A, enabling compact thermal design in TSSOP-16EP. |
| Switching Frequency | 425–575kHz - permits smaller magnetics vs 200kHz alternatives (e.g., LT1976), reducing board area by ~60% for same ripple. |
| Power Good Threshold | Programmable at 88–92% of VREF - configurable output monitoring with adjustable delay via external CT capacitor. |
| Operating Temp Range | –40°C to +125°C (junction) - qualified for under-hood automotive and industrial ambient environments. |
Pinout & Package
LT1977EFE#TRPBF is housed in a 16-lead plastic TSSOP package with exposed pad (pin 17), requiring soldering to PCB ground plane for thermal management (θJC = 10°C/W). Pin 17 is GND and must be electrically and thermally connected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (2) | Emiter of internal NPN power switch | Drives inductor; clamped externally during off-time; negative swing ≤ –0.8V allowed. |
| VIN (4) | Collector of internal NPN switch & primary supply | Supplies control circuitry when BIAS is inactive; requires low-inductance input bypass path. |
| BOOST (6) | Charge-pump drive for switch saturation | Enables <0.2Ω RCE(sat) by boosting gate drive above VIN; requires external diode + capacitor. |
| CT (7) | Power Good delay timing node | Sources/sinks current to external capacitor to set PG assertion delay; clamp at 1.2V. |
| GND (8,17) | Reference and thermal sink | Pins 8 and 17 are common ground; exposed pad (17) must be soldered to maximize heat dissipation. |
| CSS (9) | Soft-start ramp rate control | Sets dV/dt at VOUT via capacitor to output; disabled above 0.9V FB voltage. |
| BIAS (10) | Efficiency-boost auxiliary supply | Reduces VIN current draw by powering internal circuitry from regulated output (≥3V required). |
| VC (11) | Error amplifier output / current limit input | Direct access to control loop; used for compensation, current clamping, or forced shutdown. |
| FB (12) | Output voltage sensing input | Compares divider output to 1.25V reference; triggers frequency foldback and soft-start below 0.9V. |
| PGFB (13) | Power Good threshold input | Resistive divider from VOUT or VIN sets PG activation point (88–92% of VREF). |
| SYNC (14) | External clock synchronization input | Accepts 30–70% duty cycle logic signals up to 700kHz; disabled during frequency foldback. |
| SHDN (15) | Enable/disable control | Active-high; ≥1.3V enables regulator; draws <20µA; reduces IIN to <2µA in shutdown. |
| PG (16) | Open-drain Power Good output | Active-low when VPGFB < threshold; sinks 200µA; high-Z when CT clamp active. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® Operation | Reduces no-load input current to 100µA while maintaining regulation - essential for always-on automotive ECUs. |
| Load Dump Protection | Withstands 60V transients without latch-up or damage - meets ISO 7637-2 Pulse 5a requirements. |
| Programmable Power Good Flag | Configurable threshold (via PGFB divider) and delay (via CT capacitor) enable system-level power sequencing and fault detection. |
| Thermally Enhanced TSSOP-16EP | Exposed pad lowers θJA to 45°C/W - supports 1.5A continuous output without heatsink in 70°C ambient. |
| Soft-Start with dV/dt Control | Capacitor from CSS to VOUT limits inrush current during startup - prevents input brownout and output overshoot. |
| External Synchronization | SYNC pin accepts up to 700kHz logic-level clocks - enables EMI reduction via spread-spectrum or system clock alignment. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC I/O Power Supply |
|---|---|
Use Scenario: Regulating 12V battery to 3.3V for microcontroller, CAN transceiver, and sensor interface in door module. IC Role / Device Role / Timing Role: Primary buck converter providing stable, low-noise 3.3V rail with load dump immunity and ultra-low standby current. Use Value: Enables >15-year battery life in parked vehicle mode via 100µA Burst Mode quiescent current and 1µA shutdown. | Use Scenario: Converting 24V DC field bus to isolated 5V for analog input conditioning and digital logic in modular I/O card. IC Role / Device Role / Timing Role: High-efficiency non-isolated DC-DC stage delivering 1.5A with programmable PG signaling to PLC backplane controller. Use Value: Maintains regulation during 42V industrial surges and supports hot-swap capability with controlled soft-start ramp. |
| 42V Mild Hybrid Vehicle DC-DC Converter | Portable Test Equipment Power Management |
Use Scenario: Stepping down 42V starter-generator output to 12V for infotainment head unit and ADAS camera power. IC Role / Device Role / Timing Role: High-input-voltage buck regulator with synchronized switching to minimize EMI in safety-critical vision systems. Use Value: 500kHz operation allows use of 2.2µH inductor (vs 5.6µH for 200kHz), reducing size/weight by 45% in space-constrained enclosures. | Use Scenario: Battery-powered handheld tester requiring 5V/1A output from single Li-ion cell (3.0–4.2V) boosted to 12V intermediate rail. IC Role / Device Role / Timing Role: Input-stage buck converter accepting wide-range 3.3–60V input (from AC adapter or battery pack) to generate stable 5V. Use Value: Wide VIN range eliminates need for separate boost-buck topology; BIAS pin improves light-load efficiency by >15% vs VIN-only operation. |
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 |
|---|---|---|---|
| LTC3639EMSE#PBF | 40V max VIN, 1.2A output, 3mm × 4mm MSOP-16, integrated MOSFETs, 2.5µA quiescent current | Lower voltage rating; better for 24V industrial but not 42V automotive load dump | Select when ultra-low IQ (<5µA) and smaller footprint outweigh 60V requirement |
| LT8609SDE#TRPBF | 42V max VIN, 3A output, 2MHz switching, Silent Switcher® architecture, 2.5µA IQ | Higher frequency, lower EMI, higher current - but lacks programmable PG and load dump tolerance | Select when EMI-sensitive environments (e.g., RF modules) demand Silent Switcher performance and 42V suffices |
Compared with LTC3639EMSE#PBF and LT8609SDE#TRPBF, the LT1977EFE#TRPBF uniquely combines 60V absolute maximum input, programmable Power Good, and proven load dump resilience - making it the only choice for legacy 12V/42V dual-battery automotive platforms requiring long-term reliability without redesign.
Availability
LT1977EFE#TRPBF is available at Aetrix Electronics and suitable for automotive body electronics, industrial programmable logic controllers, and distributed power systems requiring stable component supply across extended temperature and voltage ranges.
Supply support for LT1977EFE#TRPBF 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. (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LT1977EFE#TRPBF belongs to ADI's high-voltage monolithic buck regulator product line, engineered specifically for harsh-environment power conversion in automotive, industrial, and transportation systems where input transients, wide VIN range, and ultra-low standby power are critical.
FAQ
What is the maximum input voltage the LT1977EFE#TRPBF can withstand during load dump events?
The LT1977EFE#TRPBF is rated for absolute maximum input voltage of 60V and explicitly designed to survive automotive load dump transients per ISO 7637-2 Pulse 5a. Its internal structure and BOOST pin architecture maintain switch saturation and regulation integrity up to this level without external clamping, provided layout follows recommended input filtering guidelines.
How does the LT1977EFE#TRPBF achieve 100µA quiescent current in Burst Mode® operation?
The LT1977EFE#TRPBF achieves 100µA quiescent current by entering Burst Mode® - a proprietary low-power state where the internal oscillator, gate drivers, and most control circuitry are periodically disabled. During sleep intervals, only essential bias circuits remain active, drawing just enough current to monitor FB voltage and reinitiate switching when output droop exceeds regulation window. This behavior is confirmed in the Electrical Characteristics table (IQ = 100µA typ at VBIAS = 0V, VFB = 1.15V).
Can the LT1977EFE#TRPBF be synchronized to an external clock, and what is its sync frequency range?
Yes, the LT1977EFE#TRPBF supports external synchronization via the SYNC pin, which accepts logic-level inputs with 30–70% duty cycle across a frequency range of 575kHz to 700kHz. This capability allows EMI reduction through frequency alignment or spread-spectrum techniques. Note that SYNC functionality is automatically disabled when FB voltage falls below 0.9V (e.g., during start-up or overload foldback), ensuring robustness during fault conditions.
What is the purpose of the BIAS pin on the LT1977EFE#TRPBF, and how does it improve efficiency?
The BIAS pin on the LT1977EFE#TRPBF provides an auxiliary power path for internal circuitry, allowing the device to draw operating current from the regulated output (≥3V) instead of VIN. When connected to VOUT, it reduces VIN supply current by up to 30% at high input voltages (e.g., 42V→5V), significantly improving light-load efficiency. This is documented in the Electrical Characteristics table where IVIN drops from 4.10mA (BIAS = 0V) to 3.25mA (BIAS = 5V) at VFB = 1.15V.
Does the LT1977EFE#TRPBF require an external catch diode, and why?
Yes, the LT1977EFE#TRPBF requires an external catch diode (e.g., 1N4148 or Schottky) between SW and GND. Because it uses an NPN transistor as the internal power switch, the collector (VIN) and emitter (SW) configuration necessitates a freewheeling path for inductor current during switch-off time. The diode clamps negative voltage at SW to ~–0.8V, preventing reverse breakdown and enabling continuous conduction mode operation - a requirement explicitly stated in the Pin Functions section of the datasheet.
LT1977EFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 60V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 55.2V
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT1977EFE#TRPBF FAQ
1.How can I place an order for LT1977EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1977EFE#TRPBF 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 LT1977EFE#TRPBF reliable?
The price and inventory of LT1977EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1977EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1977EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1977EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1977EFE#TRPBF?
LT1977EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1977EFE#TRPBF 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 LT1977EFE#TRPBF?
For technical support, including LT1977EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1977EFE#TRPBF requirements.
6.How does Aetrix verify that LT1977EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1977EFE#TRPBF 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 LT1977EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1977EFE#TRPBF?
All LT1977EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1977EFE#TRPBF, 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 LT1977EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT1977EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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