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Analog Devices Inc. LT1676CS8#TRPBF
- Part No.:
- LT1676CS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1676CS8#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 550MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,559
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Product details
Overview
LT1676CS8#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic wide-input-range step-down (Buck) switching regulator IC with true current-mode control, 7.4V–60V input range, 700mA peak switch current rating, 100kHz fixed switching frequency, and SO-8 package. It delivers regulated low-voltage outputs for telecom 48V step-down, automotive DC/DC, and IEEE 1394 power supplies.
For engineers reviewing the LT1676CS8#TRPBF datasheet, LT1676CS8#TRPBF pinout, LT1676CS8#TRPBF application, or LT1676CS8#TRPBF equivalent, key selection considerations include its adaptive dV/dt switch drive, 1.24V feedback reference, shutdown current of 30µA, and synchronization capability up to 250kHz - all critical for high-efficiency, high-input-voltage Buck designs.
Technical Context
The LT1676CS8#TRPBF implements true current-mode control using an internal transconductance error amplifier (400–1000 µmho) and a current comparator referenced to the VC pin voltage. Its dual-dV/dt output switch architecture dynamically adjusts slew rate-high dV/dt at medium-to-heavy loads for efficiency, low dV/dt at light loads to avoid pulse skipping.
It features integrated oscillator synchronization (130–250kHz), programmable undervoltage lockout via SHDN pin, and automatic oscillator slowdown (to ~25kHz) during short-circuit conditions triggered by FB voltage dropping below ~0.83V. Internal bias regulation draws power from VCC when output ≥2.9V, reducing VIN quiescent draw.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 7.4V to 60V - supports direct 48V telecom, 24V/36V automotive, and industrial HV bus inputs without pre-regulation. |
| Switch Current Limit | 0.55A to 0.70A (min to max) - sets maximum deliverable output current before cycle-by-cycle foldback. |
| Feedback Reference | 1.240V (typ), ±1.2% over temp - defines output voltage accuracy via external resistor divider (e.g., 5V = R1/R2 ≈ 3.04). |
| Switching Frequency | 100kHz (fixed), ±10% - enables compact magnetics; synchronizable to 130–250kHz for EMI reduction or multi-rail coordination. |
| Shutdown Current | 30µA (typ) - ensures ultra-low standby power in battery-backed or always-on systems. |
| Thermal Resistance | θJA = 110°C/W (SO-8) - requires ≤1.1W total dissipation to stay within 125°C junction limit at 25°C ambient. |
| VCC Operating Range | 2.8V to 3.1V dropout - mandates VCC connection to ≥3.1V output rail for efficient biasing; otherwise control circuitry draws from VIN. |
Pinout & Package
LT1676CS8#TRPBF is housed in an 8-pin plastic SOIC (SO-8) package with standard JEDEC MS-012AC footprint, 1.27mm pitch, and exposed pad not present. Thermal performance optimized for PCB copper area under pins 4 (GND) and 5 (VIN).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (1) | Shutdown enable input | Pulled low (<0.3V) disables switching and reduces input current to 30µA; open or pulled above 1.26V enables operation. |
| VCC (2) | Bias supply input | Powers internal control circuitry from output rail (≥3.1V); reduces VIN quiescent draw and improves efficiency vs. VIN-powered bias. |
| 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, internal VREF, and current sense; must be star-connected away from high-current return paths. |
| VIN (5) | Main power input | Accepts 7.4–60V; supplies switch and startup bias; requires low-ESR, high-ripple-current input capacitor. |
| SYNC (6) | Oscillator sync input | Logic-compatible input (1.5–2.2V min amplitude) to synchronize switching to external clock; disabled automatically during FB-triggered slowdown. |
| FB (7) | Inverting feedback input | Compares output divider voltage to 1.24V reference; also triggers oscillator slowdown below ~0.83V for short-circuit protection. |
| VC (8) | Error amplifier output / current comparator input | Loop compensation node; connects to RC network to ground for stability; clamped at ~2.0V for current limiting. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive dV/dt Switch Drive | Automatically selects high-slew-rate mode (>1.6 V/ns) for heavy loads and low-slew-rate mode (0.2 V/ns) for light loads - eliminates pulse skipping while maintaining >85% efficiency down to 1mA. |
| True Current-Mode Control | Uses VC pin voltage to directly set peak switch current per cycle - provides inherent cycle-by-cycle current limiting and excellent line/load transient response. |
| Auto Oscillator Slowdown | Reduces switching frequency from 100kHz to ~25kHz when FB voltage drops below 2/3 of nominal - maintains controllability and prevents current runaway during output shorts. |
| VCC-Powered Bias Regulation | Draws control power from VCC (output rail) once ≥2.9V established - cuts VIN quiescent current by >90% vs. VIN-biased controllers, enabling >90% efficiency at 48V→5V. |
| Programmable UVLO | SHDN pin allows user-defined input undervoltage lockout threshold (e.g., 12V or 24V) via resistor divider - overrides internal 6.7V UVLO without disabling it. |
Applications
| Telecom 48V Step-Down Converter | Automotive DC/DC Converter |
|---|---|
Use Scenario: Converting 48V telecom plant voltage to 3.3V or 5V for line cards, routers, and baseband processors. IC Role / Device Role / Timing Role: Primary Buck controller managing high-step-down ratio, high-input-voltage conversion with tight output regulation and fault tolerance. Use Value: 700mA peak switch current and 60V absolute max rating allow single-stage 48V→5V conversion without pre-regulator, reducing BOM count and board space. | Use Scenario: Generating stable 5V or 3.3V rails from 12V/24V/36V vehicle batteries for infotainment, ADAS sensors, and body control modules. IC Role / Device Role / Timing Role: High-reliability Buck regulator with extended temperature support (–40°C to 125°C) and robust short-circuit protection. Use Value: Auto oscillator slowdown and true current-mode control ensure safe operation during cold-crank (6.7V) and load dump (60V) transients without latch-off or damage. |
| IEEE 1394 (FireWire) Power Supply | Cellular Phone Battery Charger Accessory |
Use Scenario: Providing isolated 1.8V/3.3V power for FireWire PHY and link layer ICs in host controllers and peripherals. IC Role / Device Role / Timing Role: Compact, low-noise Buck converter synchronized to system clock via SYNC pin to minimize EMI in high-speed serial interfaces. Use Value: 100kHz fixed frequency + sync capability enables deterministic noise placement away from 1394 data bands (up to 400Mbps), easing EMC compliance. | Use Scenario: Charging auxiliary circuits (LED flash, RF front-end, USB interface) from single-cell Li-ion (3.0–4.2V) or dual-cell (6.0–8.4V) battery packs. IC Role / Device Role / Timing Role: Efficient step-down regulator delivering constant-voltage rails where input may dip near minimum operating voltage. Use Value: 7.4V minimum input and adaptive light-load drive enable reliable operation across full battery discharge curve, including low-Vbat states where other Buck ICs drop out. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | 4.5V–60V input, 1.2A switch, 3mm × 4mm MSOP; integrates power MOSFETs; no external sync input. | Higher output current, smaller footprint, but lacks SYNC pin and programmable UVLO via SHDN. | Choose LTC3631EMSE#PBF for higher current (≥1A) and space-constrained designs where sync is unnecessary. |
| LM5164QDRCRQ1 | 3.5V–65V input, 1A switch, AEC-Q100 qualified; includes hiccup-mode short-circuit protection; no VC pin for loop compensation. | Automotive-qualified with different fault response (hiccup vs. slowdown); uses internal compensation, limiting loop tuning flexibility. | Choose LM5164QDRCRQ1 for production automotive systems requiring AEC-Q100 certification and simplified design-in. |
Compared with LTC3631EMSE#PBF and LM5164QDRCRQ1, the LT1676CS8#TRPBF offers unique VC-pin-based loop compensation, SHDN-programmable UVLO, and auto oscillator slowdown - making it preferred for legacy designs requiring precise transient control, manual loop optimization, and predictable short-circuit behavior without hiccup restart delays.
Availability
LT1676CS8#TRPBF is available at Aetrix Electronics and suitable for telecom 48V step-down converters, automotive DC/DC systems, and IEEE 1394 power supplies requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1676CS8#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 semiconductor leader specializing in high-performance analog, mixed-signal, and power management ICs, acquired Linear Technology in 2017.
The LT1676CS8#TRPBF belongs to Linear's legacy high-voltage Buck controller family, designed specifically for efficient, robust step-down conversion from industrial and automotive HV buses (12V–60V) to low-voltage logic rails.
FAQ
What is the minimum input voltage required for LT1676CS8#TRPBF to start switching?
The LT1676CS8#TRPBF has a guaranteed minimum input voltage of 7.4V for normal operation, with internal undervoltage lockout (UVLO) releasing at nominally 6.7V. However, reliable startup and regulation require VIN ≥7.4V under all temperature and load conditions. Below this, the part remains in shutdown or exhibits unstable regulation. The LT1676CS8#TRPBF datasheet specifies 7.0V (typ) and 7.4V (max) as the lower bound of guaranteed operation.
Can LT1676CS8#TRPBF operate with zero load current without pulse skipping?
Yes - the LT1676CS8#TRPBF's adaptive low-dV/dt mode activates when the VC pin voltage falls below ~1.4V (corresponding to ~200mA load), relaxing minimum on-time requirements and enabling stable operation down to zero external load. Its modest VCC bias current (~4mA) provides sufficient internal loading to prevent pulse skipping in most configurations. This behavior is confirmed in the LT1676CS8#TRPBF Typical Performance Characteristics (Figure G09).
How does LT1676CS8#TRPBF protect against output short circuits?
The LT1676CS8#TRPBF employs dual short-circuit protection: (1) cycle-by-cycle current limiting via VC-clamp (~2.0V), and (2) automatic oscillator slowdown to ~25kHz when FB voltage drops below ~0.83V. This reduces effective duty cycle and limits average current, preventing thermal runaway. Unlike hiccup-mode ICs, the LT1676CS8#TRPBF maintains continuous switching - a key distinction documented in the Applications Information section.
What is the recommended layout practice for the VSW pin on LT1676CS8#TRPBF?
For the LT1676CS8#TRPBF, the VSW pin must be routed with minimal trace length and width to reduce parasitic inductance. Place the freewheeling diode and output capacitor as close as possible to VSW and GND. Avoid routing sensitive nodes (FB, VC, SHDN, SYNC) near VSW; use guard traces or ground planes. A 100pF capacitor from SHDN to GND is recommended if unused, per the LT1676CS8#TRPBF Pin Functions section, to suppress coupling from VSW.
Is LT1676CS8#TRPBF pin-compatible with other members of the LT1676 family?
Yes - the LT1676CS8#TRPBF shares identical pinout and electrical characteristics with LT1676IS8, LT1676CN8, and LT1676IN8. All variants use the same SO-8 (S8) or PDIP-8 (N8) packages and match on all DC and dynamic parameters except temperature grade and thermal resistance (θJA = 110°C/W for S8, 130°C/W for N8). No PCB changes are required when substituting between these variants.
LT1676CS8#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):
- 60V
- Voltage - Output (Min/Fixed):
- 1.24V
- Voltage - Output (Max):
- 51V
- Current - Output:
- 550mA (Switch)
- Frequency - Switching:
- 100kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1676CS8#TRPBF FAQ
1.How can I place an order for LT1676CS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1676CS8#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 LT1676CS8#TRPBF reliable?
The price and inventory of LT1676CS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1676CS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1676CS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1676CS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1676CS8#TRPBF?
LT1676CS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1676CS8#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 LT1676CS8#TRPBF?
For technical support, including LT1676CS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1676CS8#TRPBF requirements.
6.How does Aetrix verify that LT1676CS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1676CS8#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 LT1676CS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1676CS8#TRPBF?
All LT1676CS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1676CS8#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 LT1676CS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1676CS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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