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Analog Devices Inc. LT1776IS8#TRPBF
- Part No.:
- LT1776IS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1776IS8#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 550MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,987
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Product details
Overview
LT1776IS8#TRPBF from Analog Devices (formerly Linear Technology) is a wide-input, current-mode synchronous step-down switching regulator IC designed for high-efficiency DC/DC conversion in automotive and industrial power systems. It accepts 7.4V–40V input, delivers up to 700mA peak switch current, operates at 200kHz fixed frequency, tolerates 60V transients, and features adaptive switch drive for light-load efficiency without pulse skipping.
For engineers reviewing the LT1776IS8#TRPBF datasheet, LT1776IS8#TRPBF pinout, LT1776IS8#TRPBF application, or LT1776IS8#TRPBF equivalent, key selection criteria include its 1.24V reference voltage, true current-mode control architecture, SO-8 package thermal performance (θJA = 110°C/W), shutdown current of 30µA, and synchronization capability up to 400kHz.
Technical Context
The LT1776IS8#TRPBF implements a monolithic current-mode buck controller with integrated 700mA peak-rated NPN output switch and adaptive dV/dt control logic. Its dual-mode switch drive-high-slew-rate "boost" mode above VC = 1.35V and low-slew-rate mode below-enables stable operation across discontinuous and continuous conduction modes without pulse skipping.
Internal oscillator synchronization (250–400kHz range), programmable undervoltage lockout via SHDN pin, and FB-pin-dependent oscillator slowdown during short-circuit conditions provide robust system-level protection. The VCC-powered bias regulator reduces VIN supply current by shifting internal control power from VIN to VOUT after startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 7.4V to 40V continuous; survives 60V transients - enables direct connection to 24V/36V automotive rails with transient margin. |
| Switch Current Limit | 0.55A to 0.70A (min to typ over temp) - sets maximum deliverable output current before cycle-by-cycle foldback. |
| Reference Voltage | 1.225V to 1.255V (min to max) - defines output regulation accuracy; used with external resistor divider for precise VOUT setting. |
| Switching Frequency | 180kHz to 220kHz (min to max) - fixed internal oscillator allows predictable EMI profile and compact magnetics design. |
| Shutdown Current | 30µA typical - ensures ultra-low quiescent draw in standby, critical for always-on automotive modules. |
| VCC Dropout Voltage | 2.8V to 3.1V - determines minimum VOUT required to sustain internal bias regulation, enabling efficient low-VOUT operation. |
| Thermal Resistance θJA | 110°C/W (SO-8 package) - defines junction-to-ambient temperature rise per watt; informs heatsinking and layout requirements. |
Pinout & Package
LT1776IS8#TRPBF is housed in an 8-lead plastic SO (S8) package with exposed pad for thermal enhancement. Pin 4 (GND) serves as both power and signal reference; Pin 2 (VCC) powers internal circuitry from the regulated output to minimize VIN supply current.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (Pin 1) | Shutdown control input | Pull below 0.2V to enter 30µA shutdown; use external resistor divider to implement adjustable UVLO above 6.7V. |
| VCC (Pin 2) | Bias supply input | Connects to regulated output to reduce VIN current draw; requires local 0.1µF bypass if >1 inch from output cap. |
| VSW (Pin 3) | Switch emitter node | High-dI/dt, high-dV/dt node; route with minimal trace length to suppress EMI and prevent coupling into SHDN/FB. |
| GND (Pin 4) | Analog and power ground | Reference for FB amplifier and internal reference; isolate from high-current return paths to avoid regulation error. |
| VIN (Pin 5) | Main input supply | Accepts 7.4–40V; requires high-ripple-current input capacitor rated for full-switching-frequency RMS current. |
| SYNC (Pin 6) | Oscillator sync input | Logic-compatible input; synchronizes internal oscillator to external clock (250–400kHz); disabled automatically during short-circuit. |
| FB (Pin 7) | Feedback amplifier inverting input | Compares divided VOUT against 1.24V reference; low-voltage condition slows oscillator for short-circuit protection. |
| VC (Pin 8) | Control voltage output | Output of error amplifier; connects to RC compensation network; controls peak switch current via current comparator. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive Switch Drive | Switches between high- and low-dV/dt modes based on VC voltage - maintains fast response at heavy loads while avoiding pulse skipping at light loads. |
| True Current-Mode Control | Uses VC voltage to directly set peak switch current per cycle - provides inherent line and load transient rejection and simplifies loop compensation. |
| VCC-Powered Bias Regulator | Draws control power from VOUT instead of VIN after startup - reduces total input current by ~4mA at 40V input, improving full-load efficiency by ~1.5%. |
| Short-Circuit Protection | FB-pin-triggered oscillator slowdown (to ~30kHz) during low-output conditions - extends effective minimum on-time to maintain current limiting under fault. |
| Synchronization Capability | Accepts external clock up to 400kHz via SYNC pin - enables EMI reduction through frequency alignment and eliminates beat frequencies in multi-rail systems. |
Applications
| Automotive Body Control Module | Industrial Sensor Power Supply |
|---|---|
Use Scenario: Powering microcontrollers, CAN transceivers, and LIN drivers in door modules or seat controllers from a 12V/24V battery rail with load dump transients. IC Role / Device Role / Timing Role: Primary step-down regulator delivering stable 5V/3.3V with 60V transient tolerance and <30µA shutdown current for sleep-mode compliance. Use Value: Eliminates need for upstream TVS or pre-regulator stages; SO-8 thermal performance supports convection-cooled designs in sealed enclosures. | Use Scenario: Providing isolated 5V power to analog sensor front-ends (e.g., strain gauges, RTDs) in factory automation PLC I/O modules. IC Role / Device Role / Timing Role: High-efficiency buck converter operating from 24V industrial bus, rejecting line noise via current-mode control and minimizing self-heating in dense layouts. Use Value: 1.24V reference and tight FB input bias current (<1.5µA) enable ±0.5% output accuracy over temperature; SO-8 footprint eases automated assembly. |
| IEEE 1394 (FireWire) Step-Down Converter | Cellular Baseband Charger Interface |
Use Scenario: Generating 3.3V from 12V FireWire port power for physical layer ICs and link-layer controllers in host adapters. IC Role / Device Role / Timing Role: Fixed-frequency (200kHz) buck regulator with SYNC input to align switching edge with FireWire packet timing, reducing conducted EMI. Use Value: Synchronization range (250–400kHz) allows harmonic alignment with FireWire 400/800 data rates; low 30µA shutdown supports hot-plug detection. | Use Scenario: Conditioning USB-charger-derived 5V input to regulated 3.3V for cellular baseband processors in accessory dongles or docking stations. IC Role / Device Role / Timing Role: Wide-input buck regulator handling variable adapter voltages (4.75–5.25V) and transient surges during plug/unplug events. Use Value: 7.4V minimum input avoids dropout during brownout; adaptive switch drive maintains >85% efficiency down to 10mA load for standby operation. |
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 | Higher 75V max input, 1.2A switch, 3mm × 4mm MSOP-10 package; requires external compensation. | Supports higher input voltage and output current; better suited for 48V industrial or PoE-powered systems. | Select when >40V input or >700mA load is required; trade-off is larger solution size and added compensation complexity. |
| TPS54202DRCT | 4.5–28V input, 2A switch, 1.5MHz switching, integrated FETs; lower quiescent current (2µA). | Optimized for low-VIN, high-frequency, high-density applications; lacks 60V transient tolerance and adaptive dV/dt control. | Select for space-constrained consumer electronics with ≤28V input; not suitable for automotive transients or wide-VIN industrial use. |
Compared with LTC3631EMSE#PBF and TPS54202DRCT, the LT1776IS8#TRPBF uniquely balances 60V transient resilience, SO-8 manufacturability, and adaptive light-load efficiency - making it optimal for cost-sensitive, thermally constrained 24V/36V automotive and industrial converters where 700mA output suffices.
Availability
LT1776IS8#TRPBF is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor power supplies, IEEE 1394 converters, and cellular accessory chargers requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1776IS8#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 industrial, automotive, communications, and healthcare markets.
The LT1776 product line was developed by Linear Technology specifically for high-input-voltage, high-efficiency buck conversion in harsh environments - emphasizing transient resilience, thermal robustness in SO-8, and adaptive control for wide load-range efficiency.
FAQ
What is the absolute maximum input voltage rating for the LT1776IS8#TRPBF?
The LT1776IS8#TRPBF has an absolute maximum input voltage rating of 60V on both VIN and VSW pins, verified per Absolute Maximum Ratings table. This rating ensures survival during automotive load-dump transients. However, continuous operation above 40V is thermally limited by package dissipation - actual max continuous VIN depends on ambient temperature, PCB copper area, and output load.
Does the LT1776IS8#TRPBF require an external freewheeling diode, and what type is recommended?
Yes, the LT1776IS8#TRPBF requires an external Schottky freewheeling diode connected from VSW to VOUT. A Schottky diode (e.g., MBR160) is mandatory due to its low forward voltage and absence of reverse recovery charge - using ultrafast diodes causes severe VSW overshoot and potential IC damage. Diode reverse voltage rating must exceed VIN (≥60V recommended).
How does the LT1776IS8#TRPBF achieve high efficiency at light loads without pulse skipping?
The LT1776IS8#TRPBF achieves light-load efficiency via adaptive switch drive: when VC voltage falls below 1.35V, it disables the "boost" circuitry, reducing slew rate and eliminating pulse skipping. This maintains controllability down to very low currents while avoiding the audible noise and output ripple associated with discontinuous-mode skipping behavior - a key differentiator from fixed-frequency controllers.
Can the LT1776IS8#TRPBF be synchronized to an external clock, and what is the valid frequency range?
Yes, the LT1776IS8#TRPBF can be synchronized to an external clock applied to the SYNC pin. The valid synchronization range is 250kHz to 400kHz, as specified in the Electrical Characteristics table. The SYNC input is logic-compatible (1.5–2.2V amplitude, 10–90% duty cycle), and the internal oscillator automatically disables sync functionality during short-circuit conditions when FB voltage drops below ~0.83V.
What is the purpose of the VCC pin on the LT1776IS8#TRPBF, and how should it be connected?
The VCC pin on the LT1776IS8#TRPBF powers the internal control circuitry from the regulated output rather than VIN - reducing total input current and improving efficiency. It must be connected directly to the output capacitor's VOUT node. If the output capacitor is more than one inch away, a local 0.1µF ceramic bypass capacitor to GND is required at the VCC pin to ensure stable bias regulation.
LT1776IS8#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- 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):
- 7.4V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.24V
- Voltage - Output (Max):
- 34V
- Current - Output:
- 550mA (Switch)
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1776IS8#TRPBF FAQ
1.How can I place an order for LT1776IS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1776IS8#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 LT1776IS8#TRPBF reliable?
The price and inventory of LT1776IS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1776IS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1776IS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1776IS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1776IS8#TRPBF?
LT1776IS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1776IS8#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 LT1776IS8#TRPBF?
For technical support, including LT1776IS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1776IS8#TRPBF requirements.
6.How does Aetrix verify that LT1776IS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1776IS8#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 LT1776IS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1776IS8#TRPBF?
All LT1776IS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1776IS8#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 LT1776IS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1776IS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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