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Analog Devices Inc. LT1676CN8#PBF
- Part No.:
- LT1676CN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1676CN8#PBF.pdf
- Description:
- IC REG BUCK ADJ 550MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:110
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Product details
Overview
LT1676CN8#PBF from Analog Devices (formerly Linear Technology) is a wide-input, current-mode synchronous step-down DC/DC switching regulator IC designed for high-efficiency power conversion in industrial and telecom systems. It accepts 7.4V–60V input, delivers up to 700mA peak switch current, operates at fixed 100kHz (synchronizable to 250kHz), features true current mode control, and includes adaptive switch drive for stable light-load operation without pulse skipping.
For engineers reviewing the LT1676CN8#PBF datasheet, LT1676CN8#PBF pinout, LT1676CN8#PBF application, or LT1676CN8#PBF equivalent, key selection criteria include its 700mA peak switch rating, 1.24V feedback reference, SO-8/PDIP-8 package compatibility, shutdown current of 30µA, and integrated oscillator with temperature-stable frequency performance across –40°C to 125°C.
Technical Context
The LT1676CN8#PBF implements true current-mode control using an internal transconductance error amplifier (400–1000 µmho) and a dedicated current comparator referenced to the VC pin voltage. Its proprietary dual-dV/dt output switch architecture-switching between high-slew-rate (boost-enabled) and low-slew-rate (non-boost) modes based on VC threshold-maintains efficiency across load ranges while avoiding pulse skipping at light loads.
It integrates all oscillator, bias, protection, and gate-drive circuitry on a monolithic die. The VCC pin powers internal control logic from the output rail (not VIN), reducing quiescent draw from the high-voltage input; shutdown is controlled via SHDN pin with 0.5V threshold and lockout hysteresis (1.245V/1.260V), and SYNC enables external clock synchronization from 130kHz to 250kHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 7.4V to 60V - supports direct 48V telecom, automotive battery, and industrial bus inputs without pre-regulation. |
| Peak Switch Current | 700mA - defines maximum continuous output capability under typical thermal conditions in SO-8 or PDIP-8 packages. |
| Switching Frequency | 100kHz (fixed), synchronizable to 130–250kHz - enables predictable EMI filtering and compact magnetics design. |
| Feedback Reference Voltage | 1.240V (±15mV) - sets output voltage accuracy via external resistor divider; line regulation <0.01%/V ensures stability over wide VIN range. |
| Shutdown Supply Current | 30µA - minimizes system standby power loss in battery-backed or energy-sensitive applications. |
| Thermal Resistance (θJA) | 130°C/W (PDIP-8) - determines maximum power dissipation before junction exceeds 125°C at ambient 25°C. |
| Output Switch On Voltage | 1.5V max at 0.5A - contributes directly to DC conduction loss; combined with duty cycle defines PDC = VON × IOUT × D. |
Pinout & Package
LT1676CN8#PBF is housed in an 8-pin plastic DIP (PDIP-8) package with 0.3-inch body width and through-hole mounting. Pin spacing is 0.1 inch; lead finish is matte tin. Thermal performance is characterized at θJA = 130°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (Pin 1) | Shutdown control input | Pulled below 0.5V to disable switching and reduce input current to 30µA; hysteresis enables user-defined UVLO above 6.7V minimum VIN. |
| VCC (Pin 2) | Internal bias supply input | Connected to regulated output to power control circuitry-reduces VIN quiescent draw and improves full-load efficiency vs. VIN-powered controllers. |
| VSW (Pin 3) | Switch emitter node | High-dV/dt node carrying full inductor current; requires short, low-inductance PCB routing to minimize EMI and voltage overshoot. |
| GND (Pin 4) | Analog and power ground reference | Reference for FB amplifier, internal VREF, and current sense; must be star-connected near FB divider to avoid noise coupling. |
| VIN (Pin 5) | Main high-voltage input supply | Supplies output switch and startup bias; requires low-ESR, high-ripple-current input capacitor rated for ≥60V. |
| SYNC (Pin 6) | External clock synchronization input | Logic-compatible input accepting 10–90% duty cycle signals; automatically disabled during FB-induced oscillator slowdown (e.g., short-circuit). |
| FB (Pin 7) | Inverting input of error amplifier | Compares output voltage (via resistive divider) against 1.24V internal reference; low FB voltage triggers oscillator slowdown for short-circuit protection. |
| VC (Pin 8) | Error amplifier output / current comparator input | Loop compensation node-RC network to GND sets bandwidth and phase margin; also clamped at ~2V to limit peak switch current. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive dV/dt switch drive | Automatically selects high-slew (boost) or low-slew (non-boost) mode based on VC voltage-enables stable discontinuous conduction without pulse skipping. |
| Integrated VCC bias path | Draws control power from VOUT instead of VIN after startup-reduces no-load input current and improves efficiency at high VIN/low VOUT ratios. |
| FB-triggered oscillator slowdown | Reduces switching frequency linearly from 100kHz to ~25kHz when FB falls below ~0.83V-enhances short-circuit protection without external circuitry. |
| True current-mode architecture | Uses VC voltage as direct peak current command-provides inherent cycle-by-cycle current limiting and excellent line transient rejection. |
| Shutdown with lockout hysteresis | SHDN pin offers three states: off (<0.5V), lockout (0.5–1.245V), and active (>1.260V)-enables programmable undervoltage lockout independent of internal 6.7V UVLO. |
Applications
| Automotive DC/DC Converters | Telecom 48V Step-Down Converters |
|---|---|
Use Scenario: Converting unregulated 12–42V vehicle battery to stable 3.3V/5V for infotainment, ADAS sensors, or CAN transceivers. IC Role / Device Role / Timing Role: Primary buck controller managing high-input transients, load dumps, and cold-crank conditions with 60V absolute max rating. Use Value: 700mA peak switch current and 130°C/W θJA enable robust operation in engine bay environments without forced air cooling. | Use Scenario: Stepping down -48V telecom central office supply to +5V or +3.3V for line cards, DSPs, or Ethernet PHYs. IC Role / Device Role / Timing Role: High-efficiency, fixed-frequency buck controller with synchronized clock option for multi-rail noise management. Use Value: 100kHz base frequency and SYNC pin allow coordinated switching across multiple rails to suppress beat frequencies and simplify EMI filter design. |
| Cellular Phone Battery Charger Accessories | IEEE 1394 Step-Down Converters |
Use Scenario: Powering USB-C PD adapters, wireless charging bases, or multi-bay chargers requiring wide-input AC/DC front-end regulation. IC Role / Device Role / Timing Role: Secondary-side buck regulator handling variable input from primary-side flyback or LLC outputs (e.g., 12–36V). Use Value: Adaptive switch drive maintains >85% efficiency from 10mA to full load-critical for no-fan, compact charger enclosures. | Use Scenario: Generating 1.8V/3.3V rails from 12V or 24V IEEE 1394 (FireWire) bus power in digital audio/video interfaces. IC Role / Device Role / Timing Role: Low-noise, tightly regulated point-of-load converter with fast transient response for jitter-sensitive serial links. Use Value: True current-mode control delivers <5% output deviation during 100mA–500mA load steps-preserving signal integrity in high-speed data paths. |
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 | Higher integration: includes internal MOSFETs (1.5A), 3.5V–40V input, 1MHz switching, but no SYNC pin. | Replaces discrete FET+controller designs; unsuitable where external high-voltage FETs or SYNC coordination are required. | Select LTC3631EMSE#PBF only if input ≤40V and higher integration outweighs loss of 60V rating and synchronization capability. |
| LM5088MHX/NOPB | Current-mode controller with 4.5V–75V input, adjustable frequency (50kHz–1MHz), no integrated oscillator-requires external timing components. | Supports wider VIN and higher frequency; lacks built-in 100kHz oscillator and FB-triggered slowdown feature. | Choose LM5088MHX/NOPB when designing for >60V inputs or needing >250kHz operation, but accept added BOM count and no automatic short-circuit frequency reduction. |
Compared with LT1676CN8#PBF, LTC3631EMSE#PBF trades 60V input and SYNC capability for higher integration and 1.5A output, while LM5088MHX/NOPB extends input range to 75V and frequency flexibility at the cost of oscillator autonomy and FB-based protection-making LT1676CN8#PBF optimal for 48V/60V fixed-frequency, thermally constrained, or synchronized multi-rail systems.
Availability
LT1676CN8#PBF is available at Aetrix Electronics and suitable for automotive DC/DC converters, telecom 48V step-down converters, and IEEE 1394 power supplies requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT1676CN8#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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LT1676CN8#PBF belongs to Linear's legacy high-voltage buck controller product line, engineered specifically for rugged, wide-input industrial and telecom power conversion where reliability, thermal efficiency, and intrinsic protection features are critical.
FAQ
What is the maximum input voltage rating for the LT1676CN8#PBF?
The LT1676CN8#PBF has an absolute maximum input voltage rating of 60V on the VIN pin. Its operational input range is specified from 7.4V to 60V, making it suitable for 48V telecom, automotive, and industrial bus applications. Exceeding 60V risks permanent damage, and the internal UVLO is set at 6.7V minimum-so operation below 7.4V may be unstable or nonfunctional. Always observe derating guidelines per the datasheet's Absolute Maximum Ratings table.
Does the LT1676CN8#PBF require an external MOSFET or is it a complete buck solution?
The LT1676CN8#PBF is a controller IC-not a complete buck solution-and requires an external NPN transistor (or PNP-based switch) as the main power switch. It does not integrate a power MOSFET or bipolar transistor. The VSW pin connects to the emitter of the external switch, and the IC provides current-mode gate/base drive logic, oscillator, and protection. This architecture allows optimization for high-voltage, high-efficiency discrete implementations beyond what monolithic regulators can achieve.
How does the LT1676CN8#PBF handle short-circuit conditions?
The LT1676CN8#PBF handles short-circuit conditions via two coordinated mechanisms: first, true current-mode control limits peak switch current cycle-by-cycle using the VC pin voltage; second, when FB voltage drops below ~0.83V (≈2/3 of 1.24V reference), the internal oscillator frequency slows linearly from 100kHz to ~25kHz. This reduces effective duty cycle and average power delivery, preventing thermal runaway. The combination provides robust, self-contained short-circuit protection without external sensing or shutdown circuitry.
Can the LT1676CN8#PBF be synchronized to an external clock, and what is the valid frequency range?
Yes, the LT1676CN8#PBF supports external clock synchronization via the SYNC pin. It accepts logic-level signals (10–90% duty cycle) within a frequency range of 130kHz to 250kHz. The SYNC function is automatically disabled when FB voltage falls low enough to trigger oscillator slowdown (e.g., during overload or short-circuit), ensuring protection remains active regardless of external clock state. For reliable locking, the external signal amplitude must exceed 1.5V (min) and rise/fall times should be <100ns.
What is the purpose of the VCC pin on the LT1676CN8#PBF, and how should it be connected?
The VCC pin on the LT1676CN8#PBF powers the internal control circuitry-including oscillator, error amplifier, and logic-using the regulated output voltage rather than the high-voltage VIN input. It must be connected directly to the output rail (e.g., 5V or 3.3V). During startup, the IC draws bias from VIN until VOUT reaches ~2.9V, then seamlessly transitions to VCC. This reduces quiescent current drawn from VIN and improves overall efficiency-especially critical in high-VIN/low-VOUT applications like 48V-to-5V conversion.
LT1676CN8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- 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):
- 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:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1676CN8#PBF FAQ
1.How can I place an order for LT1676CN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1676CN8#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 LT1676CN8#PBF reliable?
The price and inventory of LT1676CN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1676CN8#PBF is usually 5 days.
3.What payment methods are accepted for LT1676CN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1676CN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1676CN8#PBF?
LT1676CN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1676CN8#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 LT1676CN8#PBF?
For technical support, including LT1676CN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1676CN8#PBF requirements.
6.How does Aetrix verify that LT1676CN8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1676CN8#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 LT1676CN8#PBF meets industry standards.
7.What is the process for return or replacement of LT1676CN8#PBF?
All LT1676CN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1676CN8#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 LT1676CN8#PBF part is unused and in its original packaging.
Return procedure for LT1676CN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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