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Analog Devices Inc. LT1977IFE#TRPBF
- Part No.:
- LT1977IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT1977IFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1.5A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,014
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Product details
Overview
LT1977IFE#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 conversion. 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 quiescent current-enabling efficient 14V/42V automotive systems and battery-powered applications.
For engineers reviewing the LT1977IFE#TRPBF datasheet, LT1977IFE#TRPBF pinout, LT1977IFE#TRPBF application, or LT1977IFE#TRPBF equivalent, key selection considerations include its wide 3.3–60V input range, programmable Power Good flag, soft-start capability via CSS pin, load dump protection to 60V, and thermally enhanced 16-pin TSSOP package with exposed pad.
Technical Context
The LT1977IFE#TRPBF implements constant-frequency current-mode control with an internal 500kHz oscillator, dual feedback loops (error amplifier + peak current comparator), and cycle-by-cycle current limiting. Its architecture uses a saturating NPN switch driven by a BOOST pin voltage higher than VIN to achieve low 0.2Ω on-resistance and high efficiency across wide input/output ratios.
Burst Mode® operation reduces quiescent current to 100µA at light loads by disabling non-essential circuitry while maintaining fast transient response via VC pin voltage clamping. The device integrates programmable Power Good (PGFB/CT-based delay), thermal shutdown, undervoltage lockout, and frequency foldback below 0.4V FB to protect during short-circuit conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.3V to 60V - supports 12V/24V/42V automotive systems and industrial distributed power rails without external pre-regulation. |
| Switch Current Limit | 1.5A peak - maintains regulated output under full load across full duty cycle range, enabling robust 1A continuous output designs. |
| Quiescent Current | 100µA in Burst Mode - extends battery life in always-on vehicle modules (e.g., telematics, CAN gateways) and low-power IoT sensors. |
| Switch On-Resistance | 0.2Ω - minimizes conduction loss at high currents, reducing thermal stress and enabling compact thermal design in TSSOP package. |
| Feedback Reference | 1.25V ±2.5% - enables precise output voltage setting (e.g., 3.3V, 5V, 12V) using standard resistor dividers with <0.4% error at common values. |
| Switching Frequency | 500kHz ±15% - allows smaller magnetics (e.g., 10µH inductor) vs. 200kHz alternatives, reducing board area and EMI filter size. |
| Power Good Threshold | Programmable via PGFB divider - provides configurable output voltage monitoring with user-defined delay via CT capacitor, supporting system sequencing requirements. |
| Operating Temp Range | –40°C to +125°C - qualified for under-hood automotive environments and industrial control cabinets without derating. |
Pinout & Package
LT1977IFE#TRPBF is housed in a 16-pin thermally enhanced TSSOP package (FE variant) with exposed pad (Pin 17) soldered to GND for low θJA = 45°C/W and θJC(PAD) = 10°C/W. The exposed pad must be connected to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 2) | Emiter of internal NPN power switch | Connects to inductor and catch diode cathode; handles full switch current and negative flyback voltage clamped externally. |
| VIN (Pin 4) | Collector of internal NPN switch & primary supply | High-di/dt node requiring short, low-inductance path to input capacitor; powers internal circuitry when BIAS is unconnected. |
| BOOST (Pin 6) | Boost capacitor drive terminal | Enables full saturation of NPN switch via external boost capacitor/diode; critical for achieving 0.2Ω RON at high VIN. |
| GND (Pins 8, 17) | Signal reference & thermal pad | Pins 8 and 17 are internally tied; exposed pad (17) must be soldered to large copper area for thermal management and stable regulation. |
| FB (Pin 12) | Feedback input to error amplifier | Senses output voltage via resistive divider; sets VOUT = 1.25V × (1 + R1/R2); triggers frequency foldback and soft-start when <0.9V. |
| PGFB (Pin 13) | Power Good comparator input | Configures PG threshold as % of VREF; rising edge initiates CT-based delay before PG assertion, enabling customizable power sequencing. |
| SYNC (Pin 14) | External clock synchronization input | Accepts logic-level signals (30–70% duty) up to 700kHz; disabled during frequency foldback or FB <0.9V for stability. |
| SHDN (Pin 15) | Shutdown control input | Active-high enable; >1.3V required to exit shutdown, drawing <1µA quiescent current when pulled low. |
| PG (Pin 16) | Open-drain Power Good output | Active-low signal with 200µA sink capability; high-impedance state indicates valid output after CT delay; requires pull-up resistor. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® Operation | Reduces no-load input current to 100µA while preserving fast load transient response via controlled VC pin clamping during sleep cycles. |
| Load Dump Protection | Withstands 60V transients on VIN-meets ISO 7637-2 Pulse 5a requirements for 12V/24V automotive systems without external TVS. |
| Programmable Power Good | PGFB/CT combination allows user-defined output voltage threshold (e.g., 90% of nominal) and delay time (e.g., 10ms–100ms) for safe system startup. |
| Soft-Start Control | CSS pin accepts capacitor to output to set controlled dV/dt ramp rate; prevents inrush current and stabilizes startup into large capacitive loads. |
| Thermally Enhanced Package | 16-pin TSSOP with exposed GND pad achieves θJC = 10°C/W-enables 1.5A operation at +85°C ambient without heatsink in typical layouts. |
| Current-Mode Architecture | Provides inherent cycle-by-cycle overcurrent protection, fast transient response (<10µs), and simplified loop compensation vs. voltage-mode controllers. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering 3.3V/5V rails for MCU, display controller, and audio codec in head unit with 12V/24V battery input subject to load dump transients. IC Role / Device Role / Timing Role: Primary buck regulator providing regulated DC-DC conversion with integrated load dump protection and programmable PG for safe boot sequence. Use Value: Eliminates need for external TVS and discrete PG circuit; 100µA quiescent current meets OEM standby power budgets; 60V rating withstands ISO 7637-2 Pulse 5a. | Use Scenario: Generating isolated 5V/12V supplies for digital I/O channels in factory automation PLC with 24V DC field bus input. IC Role / Device Role / Timing Role: High-efficiency step-down regulator delivering stable output under variable load and temperature (-40°C to +85°C). Use Value: 0.2Ω RON minimizes heat rise in confined enclosures; 500kHz operation enables small 10µH inductors; -40°C to +125°C rating ensures reliability in harsh environments. |
| Telecom Remote Radio Unit (RRU) | Medical Portable Diagnostic Device |
Use Scenario: Converting 48V backplane voltage to 3.3V/5V for FPGA, ADC, and RF front-end in outdoor wireless base station equipment. IC Role / Device Role / Timing Role: High-input-voltage buck converter with Burst Mode for low-noise standby operation and fast wake-up response. Use Value: 3.3–60V input range accommodates telecom PSE variations; 100µA IQ extends battery backup runtime; SYNC pin enables EMI reduction via clock alignment. | Use Scenario: Powering microcontroller, sensor interface, and Bluetooth radio in handheld ultrasound or glucose monitor with single-cell Li-ion (3.0–4.2V) or two-cell pack (6–8.4V). IC Role / Device Role / Timing Role: Efficient step-down regulator supporting wide input range and ultra-low quiescent current for long battery life. Use Value: Burst Mode extends battery life >3× vs. forced PWM; soft-start prevents inrush into capacitive medical displays; 1.25V reference enables precise 3.3V rail for analog sensors. |
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 input, 1.5A, 3MHz sync capability, 2.5µA IQ in shutdown, no BOOST pin, uses MOSFET switch | Better for space-constrained, high-frequency designs; lacks 60V rating and load dump protection | Select for compact 3.3V/5V point-of-load where input ≤40V and lowest possible footprint matters more than automotive transients. |
| LM5164QPWPRQ1 | 65V max input, 1A, 100µA IQ, integrated MOSFET, spread-spectrum EMI reduction, AEC-Q100 Grade 1 | Higher VIN rating but lower current; automotive-qualified with spread spectrum; no programmable PG or soft-start pin | Select for AEC-Q100-compliant automotive body electronics where 1A output suffices and EMI compliance is critical. |
Compared with LTC3639EMSE#PBF and LM5164QPWPRQ1, the LT1977IFE#TRPBF uniquely combines 60V input, 1.5A current, programmable Power Good, and load dump protection in a single monolithic solution-making it optimal for cost-sensitive, high-reliability 14V/42V automotive and industrial power rails where discrete protection is undesirable.
Availability
LT1977IFE#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC power supplies, and telecom remote radio units requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT1977IFE#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. (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 LT1977IFE#TRPBF belongs to Linear's high-voltage monolithic buck regulator product line, engineered specifically for robust, efficient DC-DC conversion in 12V/24V/42V automotive and industrial power systems where wide input range, low IQ, and transient resilience are critical.
FAQ
What is the absolute maximum input voltage rating for the LT1977IFE#TRPBF?
The LT1977IFE#TRPBF has an absolute maximum input voltage rating of 60V on the VIN pin. This rating also applies to SHDN, BIAS, SW, and PG pins. Exceeding this voltage-even transiently-may damage the device. Input voltage transients such as load dump pulses must be clamped externally if they exceed 60V, though the part is designed to withstand ISO 7637-2 Pulse 5a (60V/100ms) without additional protection under typical conditions.
How does the BOOST pin function in the LT1977IFE#TRPBF, and what external components are required?
The BOOST pin in the LT1977IFE#TRPBF supplies a boosted gate drive voltage to fully saturate the internal NPN power switch, enabling its low 0.2Ω on-resistance. It requires an external boost capacitor (typically 2.2µF, 100V ceramic) and a Schottky diode (e.g., 1N4148 or B1100) connected from SW to BOOST. During switch turn-on, the diode charges the capacitor; during turn-off, the charged capacitor drives the BOOST pin above VIN to ensure deep saturation and minimal VCE(sat).
Can the LT1977IFE#TRPBF be synchronized to an external clock, and what are the timing constraints?
Yes, the LT1977IFE#TRPBF can be synchronized to an external clock via the SYNC pin, which accepts logic-level inputs (30–70% duty cycle) from 425kHz to 700kHz. Synchronization is disabled when the FB pin voltage falls below 0.9V (e.g., during startup or fault conditions) to preserve frequency foldback behavior. The SYNC pin has 85kΩ input impedance and requires no external pull-up; it must be left floating or pulled low to disable sync mode.
What is the purpose of the CSS pin on the LT1977IFE#TRPBF, and how is it configured?
The CSS pin on the LT1977IFE#TRPBF controls soft-start by accepting a capacitor connected between CSS and the output voltage. The current sourced into CSS increases with FB voltage; when it exceeds the CSS threshold (7–20µA), the VC pin is clamped to limit output dV/dt. A typical 10nF capacitor yields ~10ms ramp time for a 3.3V output. Soft-start is automatically defeated when FB >0.9V, and CSS has no effect during normal regulation.
Does the LT1977IFE#TRPBF support adjustable output voltage, and what is the tolerance of its internal reference?
Yes, the LT1977IFE#TRPBF supports adjustable output voltage via an external resistor divider on the FB pin, referenced to its 1.25V internal bandgap. The reference voltage is specified as 1.225V to 1.275V (±2.5%) over –40°C to +125°C junction temperature, ensuring stable output accuracy across automotive and industrial operating ranges. Standard 1% resistors yield typical output errors <0.4% for common voltages like 3.3V and 5V.
LT1977IFE#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:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT1977IFE#TRPBF FAQ
1.How can I place an order for LT1977IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1977IFE#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 LT1977IFE#TRPBF reliable?
The price and inventory of LT1977IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1977IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1977IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1977IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1977IFE#TRPBF?
LT1977IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1977IFE#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 LT1977IFE#TRPBF?
For technical support, including LT1977IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1977IFE#TRPBF requirements.
6.How does Aetrix verify that LT1977IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1977IFE#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 LT1977IFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1977IFE#TRPBF?
All LT1977IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1977IFE#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 LT1977IFE#TRPBF part is unused and in its original packaging.
Return procedure for LT1977IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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