My Inquiry
My Account
Analog Devices Inc. LT1776CS8#PBF
- Part No.:
- LT1776CS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1776CS8#PBF.pdf
- Description:
- IC REG BUCK ADJ 550MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,679
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT1776CS8#PBF from Analog Devices (formerly Linear Technology) is a monolithic, current-mode, step-down switching regulator IC designed for high-input-voltage DC/DC conversion. It accepts 7.4V–40V input, delivers up to 700mA peak switch current, operates at fixed 200kHz (synchronizable to 400kHz), and features adaptive switch drive for efficiency across load range. It is used in automotive DC/DC converters requiring transient tolerance up to 60V.
For engineers reviewing the LT1776CS8#PBF datasheet, LT1776CS8#PBF pinout, LT1776CS8#PBF application, or LT1776CS8#PBF equivalent, key selection criteria include its wide VIN range (7.4V–40V), true current-mode control architecture, 1.24V reference voltage with ±1.2% initial accuracy, shutdown quiescent current of 30µA, and SO-8 package compatibility with thermal design constraints (θJA = 110°C/W).
Technical Context
The LT1776CS8#PBF implements a proprietary bipolar output switch with dual dV/dt modes: high-slew-rate operation above 1.35V VC threshold for heavy loads, and reduced-slew-rate mode below that threshold to suppress pulse skipping at light loads. Its internal oscillator supports synchronization via the SYNC pin (1.5V–2.2V amplitude, 250–400kHz range) and automatically slows to ~30kHz under short-circuit conditions when FB falls below ~0.83V.
Control is implemented through a transconductance feedback amplifier (gm = 400–1000 µmho) referenced to a 1.24V bandgap, with VC serving as both error amplifier output and current comparator input. The SHDN pin provides programmable undervoltage lockout (UVLO) with upper/lower thresholds at 1.260V/1.245V, logically ANDed with the internal 6.7V UVLO.
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 or industrial rails without pre-regulation. |
| Switch Current Limit | 0.55A to 1.0A (typ. 0.7A) - sets maximum deliverable output power and defines short-circuit current foldback behavior. |
| Reference Voltage | 1.240V ±1.2% (initial) - determines output voltage accuracy via external resistor divider (e.g., 5V output uses 12.1kΩ/22kΩ). |
| Switching Frequency | 200kHz fixed (±10%), synchronizable to 250–400kHz - balances EMI, inductor size, and efficiency for medium-power buck designs. |
| Shutdown Current | 30µA (typ.) - minimizes system standby power in battery-backed or always-on applications. |
| Thermal Resistance | θJA = 110°C/W (SO-8) - requires careful PCB copper area planning for >300mA continuous loads at high ambient temperatures. |
| Feedback Transconductance | 400–1000 µmho - defines loop gain stability margin and compensation network sensitivity to capacitor ESR. |
Pinout & Package
LT1776CS8#PBF is housed in an 8-lead plastic SOIC (SO-8) package with standard 1.27mm pitch and exposed pad not present. Thermal performance relies on PCB copper area connected to GND pins (pins 4 and 7).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (1) | Shutdown enable input | Logic-low (<0.3V) disables switching and reduces VIN current to ~30µA; 0.2–0.8V range enables UVLO programming via external divider. |
| VCC (2) | Bias supply input | Powers internal circuitry from output rail (not VIN) after startup - improves efficiency by reducing quiescent draw from high-VIN source. |
| VSW (3) | Switch emitter node | High-dV/dt node carrying full inductor current; requires short, low-inductance routing to minimize EMI and voltage overshoot. |
| GND (4) | Analog/digital ground reference | Reference for FB amplifier, VREF, and internal bias - must be star-connected near FB divider to avoid noise coupling. |
| VIN (5) | Main power input | Supplies output switch and startup bias; rated for 60V transients but thermally limited to 40V continuous at full load. |
| SYNC (6) | Oscillator sync input | Accepts logic-level square wave (10–90% duty); disables sync automatically during short-circuit when FB <0.83V. |
| FB (7) | Inverting feedback input | Compares output divider voltage to 1.24V reference; low voltage (<0.83V) triggers oscillator slowdown for short-circuit protection. |
| VC (8) | Error amplifier output / current comparator input | Loop compensation node - RC network to GND sets bandwidth and phase margin; clamped at 2.0V for overcurrent limiting. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive dV/dt switch drive | Switches between high-slew (heavy load) and low-slew (light load) modes using VC threshold - eliminates pulse skipping while maintaining controllability down to zero load. |
| True current-mode control | Uses instantaneous switch current sensing via VC pin - provides inherent cycle-by-cycle current limiting and excellent line regulation without slope compensation. |
| Auto-reducing oscillator frequency | Slows from 200kHz to ~30kHz when FB drops below 0.83V - maintains stable current limiting during output short-circuit without external intervention. |
| VCC-powered bias circuitry | Draws operating current from regulated output (not VIN) after startup - reduces no-load input current by >90% vs VIN-powered controllers at high input voltages. |
| Programmable UVLO | SHDN pin allows user-defined turn-on threshold above internal 6.7V UVLO - enables precise brown-out protection in automotive systems with varying battery profiles. |
Applications
| Automotive DC/DC Conversion | IEEE 1394 Step-Down Supply |
|---|---|
Use Scenario: Converting 12V–36V vehicle battery rail to stable 5V or 3.3V for infotainment ECUs or ADAS sensors. IC Role / Device Role / Timing Role: Primary buck controller managing transient-heavy loads with 60V surge tolerance and thermal robustness. Use Value: Eliminates need for external TVS or pre-regulator stages; maintains regulation during cold-crank (6.7V) and load-dump (60V) events per ISO 7637-2. | Use Scenario: Generating 3.3V from 12V auxiliary rail in FireWire (IEEE 1394a/b) host controllers or peripherals. IC Role / Device Role / Timing Role: High-efficiency, low-noise point-of-load regulator synchronized to system clock via SYNC pin. Use Value: Synchronization prevents beat-frequency EMI in high-speed serial interfaces; 200kHz operation avoids critical USB/FireWire harmonics. |
| Cellular Baseband Power | Industrial Sensor Node Supply |
Use Scenario: Providing 2.8V/3.3V for cellular modem baseband processors in portable test equipment or IoT gateways. IC Role / Device Role / Timing Role: Efficient, compact DC/DC converter supporting dynamic load steps from sleep to transmit bursts. Use Value: Adaptive dV/dt mode ensures stable regulation during rapid 10mA ↔ 400mA load transitions without audible switching noise or output droop. | Use Scenario: Powering low-power microcontrollers and analog front-ends in wired industrial sensors (e.g., 4–20mA loop-powered devices). IC Role / Device Role / Timing Role: Standby-optimized buck regulator enabling multi-year battery life with <30µA shutdown current. Use Value: Ultra-low shutdown current extends shelf life and runtime; SO-8 package allows compact 2-layer PCB layout compatible with IPC-7351B footprints. |
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 VIN, 100mA output, integrated MOSFETs, 3mm × 4mm MSOP - lower current, higher integration, no external diode needed. | Suitable for ultra-compact, low-power applications where 700mA is excessive; lacks SYNC and adaptive dV/dt. | Select LTC3631EMSE#PBF when board space is constrained and output current ≤100mA; not drop-in for LT1776CS8#PBF due to different pinout and current capability. |
| LM5009AMM/NOPB | 80V max VIN, 500mA peak switch, 2.2MHz fixed frequency, current-mode - higher voltage rating, much higher frequency, smaller magnetics. | Better suited for high-density, high-input-voltage designs where 200kHz inductors are too large; requires different compensation and layout. | Select LM5009AMM/NOPB when input exceeds 40V or when 2.2MHz operation is required to shrink passive size; not pin-compatible and needs revised loop compensation. |
Compared with LTC3631EMSE#PBF and LM5009AMM/NOPB, the LT1776CS8#PBF uniquely balances 700mA capability, 200kHz operation for low EMI, adaptive light-load efficiency, and proven automotive transient robustness - making it optimal for mid-power industrial and automotive buck supplies where reliability and thermal manageability are prioritized over miniaturization or extreme VIN range.
Availability
LT1776CS8#PBF is available at Aetrix Electronics and suitable for automotive DC/DC converters, IEEE 1394 power supplies, and industrial sensor node designs requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1776CS8#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, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and power management ICs, acquired Linear Technology in 2017 to expand its precision power portfolio.
The LT1776CS8#PBF belongs to Linear's legacy high-voltage buck regulator family, engineered specifically for rugged, wide-input industrial and automotive power conversion where efficiency, transient immunity, and thermal resilience outweigh ultra-high integration or MHz-class switching.
FAQ
What is the maximum continuous input voltage rating for the LT1776CS8#PBF?
The LT1776CS8#PBF is rated for continuous operation from 7.4V to 40V input. While it can survive transient inputs up to 60V (per Absolute Maximum Ratings), sustained operation above 40V violates thermal limits in the SO-8 package - especially at >300mA load - due to increased switching loss proportional to VIN². Derating is required per the thermal data: θJA = 110°C/W.
Does the LT1776CS8#PBF require an external freewheeling diode, and what type is recommended?
Yes, the LT1776CS8#PBF requires an external Schottky diode (e.g., MBR160) connected from VSW to VOUT. Schottky diodes are mandatory due to their low forward voltage (minimizing conduction loss) and absence of reverse recovery charge (preventing VSW overshoot and RFI). Ultrafast or standard PN diodes must be avoided - their reverse recovery causes destructive voltage spikes exceeding 60V at the VSW node.
How does the LT1776CS8#PBF handle short-circuit conditions?
The LT1776CS8#PBF handles short circuits via dual mechanisms: (1) true current-mode control limits peak switch current to ~0.7A, and (2) automatic oscillator slowdown - when FB voltage drops below ~0.83V, fOSC linearly decreases from 200kHz to ~30kHz, extending minimum on-time to maintain cycle-by-cycle current limiting. This prevents current runaway and eliminates need for external fault latches.
Can the LT1776CS8#PBF be synchronized to an external clock, and what are the requirements?
Yes, the LT1776CS8#PBF supports synchronization via the SYNC pin, accepting logic-level square waves from 250kHz to 400kHz with 10–90% duty cycle. Minimum sync amplitude is 1.5V (typ.), and input impedance is 40kΩ. Critically, sync is automatically disabled if FB falls below 0.83V - ensuring short-circuit protection remains active even when externally clocked.
What is the purpose of the VCC pin on the LT1776CS8#PBF, and how should it be connected?
On the LT1776CS8#PBF, the VCC pin powers internal control circuitry from the regulated output rail (not VIN), significantly improving efficiency - especially at high input voltages. It must be connected directly to VOUT (or a filtered version thereof) with a local 0.1µF ceramic bypass capacitor. If left open, the IC reverts to VIN-powered operation, increasing quiescent current and reducing efficiency by ~3–5% at 40V input.
LT1776CS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1776CS8#PBF FAQ
1.How can I place an order for LT1776CS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1776CS8#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 LT1776CS8#PBF reliable?
The price and inventory of LT1776CS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1776CS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1776CS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1776CS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1776CS8#PBF?
LT1776CS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1776CS8#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 LT1776CS8#PBF?
For technical support, including LT1776CS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1776CS8#PBF requirements.
6.How does Aetrix verify that LT1776CS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1776CS8#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 LT1776CS8#PBF meets industry standards.
7.What is the process for return or replacement of LT1776CS8#PBF?
All LT1776CS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1776CS8#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 LT1776CS8#PBF part is unused and in its original packaging.
Return procedure for LT1776CS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT1776CS8#PBF Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
