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Analog Devices Inc. LT1680IN#PBF
- Part No.:
- LT1680IN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1680IN#PBF.pdf
- Description:
- IC REG CTRLR BST/FWRD CONV 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:123
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Product details
Overview
LT1680IN#PBF from Analog Devices (formerly Linear Technology) is a high-power, current-mode DC/DC boost controller optimized for 12V–60V input applications driving N-channel MOSFETs. It delivers programmable average current limiting (120 mV threshold), fixed-frequency operation up to 200 kHz, and 5 V reference output with 10 mA load capability - enabling robust 48 V/5.2 A battery backup systems.
For engineers reviewing the LT1680IN#PBF datasheet, LT1680IN#PBF pinout, LT1680IN#PBF application, or LT1680IN#PBF equivalent, key selection considerations include its 60 V sense common-mode range, 10,000 pF gate drive capability, undervoltage lockout with hysteresis (9.0 V rising / 8.2 V falling), soft-start control via external capacitor, and slope compensation adjustability for >50% duty cycle stability.
Technical Context
The LT1680IN#PBF implements a constant-frequency current-mode control architecture with internal transconductance error amplifier (2000 µmho typ), programmable oscillator (RCT/CCT-based), and dual current-limiting: peak sensing (190 mV) and user-configurable average limiting (120 mV at IAVG pin). Its VC pin serves as integrator output and current comparator threshold reference.
It integrates precision functions including bandgap-referenced 1.25 V feedback threshold, 5 V reference with ±25 mV tolerance over temperature, RUN/SHDN shutdown with 1.25 V threshold and 25 mV hysteresis, and minimum off-time protection (~1 µs). The SL/ADJ pin enables external slope compensation tuning without affecting average current limit accuracy.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | –0.3 V to 20 V on 12VIN pin; sense common-mode up to 60 V - enables direct high-side current sensing without blanking circuits |
| Operating Frequency | Programmable up to 200 kHz; synchronized TTL-compatible SYNC input - supports EMI reduction and multi-rail timing coordination |
| Average Current Limit | 120 mV threshold at SENSE pins; set via external RC on IAVG pin - provides stable DC current regulation independent of ripple or duty cycle |
| 5 V Reference Output | 4.75–5.25 V, ±10 mA DC load - powers external timing components, bias networks, or logic without auxiliary supply |
| Gate Drive Capability | 11.9 V high-side output, 60 ns rise/fall, drives up to 10,000 pF - supports paralleled high-current MOSFETs (e.g., IRFZ44 ×3) |
| Undervoltage Lockout | 9.0 V rising / 8.2 V falling threshold with 350 mV hysteresis - prevents erratic startup during brownout conditions |
| Temperature Range | –40°C to +85°C ambient - qualified for industrial and automotive under-hood environments |
Pinout & Package
LT1680IN#PBF is housed in a 16-lead PDIP (N package) with 75°C/W junction-to-ambient thermal resistance. Pin assignments are validated per Linear Technology's official LT1680 datasheet Rev. C (2002).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SL/ADJ (1) | Slope compensation adjustment | Resistive divider from 5VREF sets additional ramp gain - stabilizes control loop above 50% duty cycle without degrading average current limit accuracy |
| CT (2) | Oscillator timing node | Connects RCT (to 5VREF) and CCT (to SGND) - sets free-run frequency and minimum off-time; discharge current = 2.5 mA (typ) |
| IAVG (3) | Average current limit integrator | 50 kΩ output impedance forms single-pole filter with external capacitor - disables average limit if shorted to SGND |
| SS (4) | Soft-start timing | Sources 8 µA to external capacitor - ramps VC clamp voltage linearly, controlling inrush current during startup and UVLO recovery |
| VC (5) | Error amplifier output | Transconductance amplifier output (2000 µmho); dominant pole compensation via RC to SGND - defines loop stability and transient response |
| SGND (6) | Small-signal ground | Reference for feedback, reference, and error amplifier - must be star-connected to COUT negative terminal to avoid noise coupling |
| VFB (7) | Error amplifier inverting input | 1.25 V internal reference node; 0.5 µA bias current - sets output voltage via resistor divider (VOUT = 1.25 × (1 + R2/R1)) |
| VREF (8) | Bandgap reference decoupling | Internal 1.25 V reference; requires ≥0.1 µF bypass to SGND - ensures stable feedback reference under dynamic load |
| SENSE+ (9) | Current sense inverting input | Connects to high-side of sense resistor - supports high-common-mode sensing up to 60 V relative to PGND |
| SENSE– (10) | Current sense noninverting input | Connects to low-side of sense resistor - differential input rejects common-mode noise; offset < 0.1 mV |
| RUN/SHDN (11) | Shutdown enable input | 1.25 V precision threshold with 25 mV hysteresis - enables power sequencing or VIN undervoltage detection without external comparator |
| PGND (12) | Power ground | Return path for GATE driver and sense amplifier - must be low-impedance connection to VIN decoupling capacitor |
| GATE (13) | N-channel MOSFET driver output | 11.9 V swing, 60 ns transition, 10,000 pF load - directly drives high-current discrete FETs without external buffer |
| 12VIN (14) | Main supply input | –0.3 V to 20 V operating range; powers internal circuitry - bypass with ≥1 µF ceramic to PGND close to pin |
| SYNC (15) | Oscillator synchronization input | TTL-compatible rising-edge trigger; reduces CT high-threshold to 2.0 V for ~200 ns - allows precise multi-converter phase alignment |
| 5VREF (16) | 5 V reference output | 4.75–5.25 V, 10 mA DC capable - supplies RCT, CCT, and external logic; disabled during shutdown |
Key Features
| Feature | Design Value |
|---|---|
| Programmable average current limiting | Enables precise DC magnetic current control (e.g., 250 W boost converter) without sensitivity to ripple amplitude or duty cycle variation |
| User-adjustable slope compensation | SL/ADJ pin allows external tuning to stabilize >50% duty cycle operation while preserving full average current limit capability |
| 60 V current sense common-mode range | Eliminates need for isolated sense amplifiers or level-shifters in high-input-voltage boost configurations |
| Integrated 5 V reference with 10 mA drive | Reduces BOM count by powering timing resistors/capacitors and external monitoring circuitry from a single regulated source |
| Minimum off-time protection | ~1 µs forced dead time prevents shoot-through and ensures safe switching during overload or short-circuit events |
Applications
| High Power Single Board Systems | Distributed Power Converters |
|---|---|
Use Scenario: 12 V to 48 V, 250 W boost converter powering FPGA-based processing modules on industrial backplanes. IC Role / Device Role / Timing Role: Primary current-mode controller managing N-channel MOSFET switching, feedback regulation, and sequencing via RUN/SHDN. Use Value: Delivers stable 48 V/5.2 A output with >95% efficiency at full load; average current limiting prevents transformer saturation during transient surges. | Use Scenario: Rack-mounted telecom shelf with multiple isolated 48 V outputs derived from a shared 12 V intermediate bus. IC Role / Device Role / Timing Role: Standalone boost controller synchronizing to system clock via SYNC pin for EMI reduction across parallel converters. Use Value: Enables tight output voltage regulation (±1%) and coordinated switching across distributed loads, minimizing conducted emissions. |
| Lead-Acid Battery Back-Up Systems | Industrial Control Systems |
Use Scenario: Uninterruptible power supply maintaining 48 V DC for PLC I/O modules during AC mains failure using 12 V lead-acid bank. IC Role / Device Role / Timing Role: High-reliability boost controller with UVLO hysteresis and soft-start to prevent inrush damage during battery recovery. Use Value: Ensures seamless switchover with no output droop; programmable average current limit protects battery from excessive discharge currents. | Use Scenario: Motor drive auxiliary supply generating 48 V from 24 V vehicle battery for sensor excitation and CAN transceiver bias. IC Role / Device Role / Timing Role: Robust controller operating across –40°C to +85°C with wide-input tolerance and fault protection. Use Value: Maintains regulation during cold cranking (down to 8.2 V input) and hot idle (up to 16 V), meeting ISO 16750-2 automotive requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3780EFE#PBF | Wide-input synchronous buck-boost controller (4–36 V); integrated gate drivers; no 60 V sense range | Requires external high-side switch for >36 V inputs; lacks SL/ADJ slope tuning; supports bidirectional conversion | Prefer LTC3780 for compact synchronous designs below 36 V input; LT1680IN#PBF remains superior for >40 V boost-only topologies requiring high-side sensing |
| LM5022MM/NOPB | Current-mode boost controller with 65 V max input; fixed 500 kHz freq; no average current limit or SL/ADJ | Higher switching frequency enables smaller magnetics but less thermal margin; no programmable average limit or slope adjust | Choose LM5022 for cost-sensitive, space-constrained 48 V boost where average current precision is secondary to size |
Compared with LTC3780EFE#PBF and LM5022MM/NOPB, the LT1680IN#PBF uniquely combines 60 V sense common-mode range, user-adjustable slope compensation, and true average current limiting - making it the only option validated for high-power, high-duty-cycle industrial boost converters requiring long-term magnetic reliability.
Availability
LT1680IN#PBF is available at Aetrix Electronics and suitable for high-power single board systems, distributed power converters, and industrial control systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT1680IN#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT1680IN#PBF belongs to Linear's legacy high-power DC/DC controller product line, designed specifically for ruggedized boost converter applications in industrial, telecom, and automotive backup power systems.
FAQ
What is the maximum input voltage supported by the LT1680IN#PBF for reliable operation?
The LT1680IN#PBF supports a 12VIN supply voltage range of –0.3 V to 20 V. Its current sense amplifier has a common-mode input range up to 60 V, allowing high-side sensing in boost topologies where input may reach 60 V. Absolute maximum ratings prohibit exceeding 20 V on the 12VIN pin itself - external clamping or regulation is required for inputs above this level. This dual-voltage-domain design enables use in 48 V input systems with proper front-end conditioning.
How does the LT1680IN#PBF implement average current limiting, and what is its typical threshold?
The LT1680IN#PBF implements average current limiting via the IAVG pin, which integrates the output of the current sense amplifier using an external capacitor and the pin's 50 kΩ output impedance. The average limit threshold is 120 mV across the external sense resistor (RSENSE), corresponding to a typical trip point of 120 mV / RSENSE. This function remains accurate regardless of duty cycle or ripple current magnitude - unlike peak limiting - and can be disabled by shorting IAVG to SGND.
Can the LT1680IN#PBF be synchronized to an external clock, and what are the electrical requirements?
Yes, the LT1680IN#PBF supports oscillator synchronization via the SYNC pin (Pin 15), which accepts TTL-level signals. The input requires minimum high/low pulse widths of ≥1 µs (i.e., ≤10% or ≥90% duty cycle at 100 kHz). The internal one-shot reduces the CT pin high threshold from 2.5 V to 2.0 V for ~200 ns upon each rising edge. No internal pull-up exists - SYNC must be actively driven or pulled to SGND when unused.
What is the purpose of the SL/ADJ pin on the LT1680IN#PBF, and how is it used?
SL/ADJ (Pin 1) provides user-adjustable slope compensation to stabilize current-mode control at duty cycles above 50%. Connecting a resistor divider from 5VREF to SL/ADJ increases effective ramp slope without affecting average current limit accuracy. Floating or tying SL/ADJ to 5VREF disables additional compensation. This feature preserves full current sourcing capability while preventing subharmonic oscillation - critical for high-efficiency, high-duty-cycle boost designs.
Does the LT1680IN#PBF include built-in protection features, and which ones are active during startup?
Yes, the LT1680IN#PBF integrates undervoltage lockout (UVLO) with 9.0 V rising / 8.2 V falling thresholds and 350 mV hysteresis, plus soft-start controlled by the SS pin (8 µA charge current). During startup, UVLO holds all internal functions disabled until 12VIN exceeds 9.0 V; then soft-start gradually raises the VC clamp voltage, limiting inductor current ramp rate. RUN/SHDN shutdown and minimum off-time (~1 µs) protection are also active, preventing switch stress during faults.
LT1680IN#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Boost, Forward Converter
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 9V ~ 60V
- Frequency - Switching:
- -
- Duty Cycle (Max):
- 90%
- Synchronous Rectifier:
- No
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
LT1680IN#PBF FAQ
1.How can I place an order for LT1680IN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1680IN#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 LT1680IN#PBF reliable?
The price and inventory of LT1680IN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1680IN#PBF is usually 5 days.
3.What payment methods are accepted for LT1680IN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1680IN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1680IN#PBF?
LT1680IN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1680IN#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 LT1680IN#PBF?
For technical support, including LT1680IN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1680IN#PBF requirements.
6.How does Aetrix verify that LT1680IN#PBF is sourced from the original manufacturer or authorized distributors?
All LT1680IN#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 LT1680IN#PBF meets industry standards.
7.What is the process for return or replacement of LT1680IN#PBF?
All LT1680IN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1680IN#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 LT1680IN#PBF part is unused and in its original packaging.
Return procedure for LT1680IN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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