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Analog Devices Inc. LT1680ISW#PBF
- Part No.:
- LT1680ISW#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LT1680ISW#PBF.pdf
- Description:
- IC REG CTLR BST/FWRD CONV 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:554
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Product details
Overview
LT1680ISW#PBF from Analog Devices (formerly Linear Technology) is a high-power, current-mode DC/DC step-up controller optimized for boost topologies, driving N-channel MOSFETs with up to 10,000 pF gate capacitance, operating from 12 V input up to 60 V, and supporting fixed-frequency operation up to 200 kHz. It delivers programmable average current limiting (120 mV threshold), 5 V reference output (±25 mV tolerance, 10 mA load), and undervoltage lockout with 350 mV hysteresis - enabling robust 48 V/5.2 A industrial boost converters.
For engineers reviewing the LT1680ISW#PBF datasheet, LT1680ISW#PBF pinout, LT1680ISW#PBF application, or LT1680ISW#PBF equivalent, key selection considerations include its 16-lead SO Wide (SW) package, 120 mV average current limit threshold, 1.25 V error amplifier reference, 90% max duty cycle support with slope compensation, and compatibility with high-input-voltage industrial and automotive power sequencing requirements.
Technical Context
The LT1680ISW#PBF implements a constant-frequency, current-mode control architecture with an internal oscillator programmable via RCT/CCT, capable of synchronization up to 200 kHz. Its transconductance error amplifier (1200–3200 µmho, 1500–3000 V/V gain) drives the VC pin to modulate the current comparator threshold, enabling precise regulation of output voltage via external feedback resistors.
It integrates dual current sensing: peak current detection (170–190 mV threshold) for cycle-by-cycle protection and average current limiting (110–130 mV at sense inputs, 2.5 V at IAVG pin) using an external integrator capacitor. Slope compensation is user-adjustable via SL/ADJ pin to stabilize operation above 50% duty cycle, and minimum off-time (~1 µs) protects the external switch during overload.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Frequency | Programmable up to 200 kHz; enables compact magnetics and EMI control in high-power boost designs. |
| Average Current Limit Threshold | 110–130 mV at SENSE pins; sets precise DC input current limit independent of ripple, critical for battery and supply protection. |
| 5V Reference Output | 4.75–5.25 V, ±25 mV tolerance, 10 mA DC load; powers timing components and local biasing without external regulator. |
| Error Amplifier Reference | 1.235–1.265 V at VFB pin; defines regulated output voltage via resistor divider (VOUT = 1.25V × (1 + R2/R1)). |
| Input Voltage Range (12VIN) | –0.3 V to 20 V; supports 12 V nominal rail with margin for transients and sequencing in industrial systems. |
| Current Sense Common Mode | –0.3 V to 60 V; allows direct high-side sensing on input rail, eliminating need for blanking circuits or isolated amplifiers. |
| Undervoltage Lockout | Falling threshold 8.20–9.75 V, rising 9.35–9.95 V, 200–350 mV hysteresis; ensures clean startup and prevents brownout oscillation. |
Pinout & Package
LT1680ISW#PBF is housed in a 16-lead plastic SO Wide (SW) package (10.3 mm × 7.5 mm, 1.27 mm pitch), rated for –40°C to +85°C ambient operation with θJA = 90°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SL/ADJ (1) | Slope compensation adjustment | Resistive loading tailors additional ramp for stable >50% duty cycle operation; floating or tied to 5VREF disables extra compensation. |
| CT (2) | Oscillator timing node | Connects external RCT/CCT to set frequency; discharge current (2.1–2.75 mA) determines min off-time and max duty cycle. |
| IAVG (3) | Average current limit integrator | 50 kΩ output impedance forms single-pole integrator with external cap (e.g., 220 pF to VC); shorting to SGND disables avg limit. |
| SS (4) | Soft start timing | Sources ~8 µA to external capacitor; ramps VC clamp voltage for controlled current limit rise and graceful output voltage ramp. |
| VC (5) | Error amplifier output | Drives current comparator threshold; RC network here provides dominant pole compensation for loop stability. |
| SGND (6) | Small-signal ground | Reference for feedback, reference, and error amp; must be star-connected to COUT negative terminal to minimize noise coupling. |
| VFB (7) | Error amp inverting input | Senses output voltage via resistor divider; sources 0.1–1.0 µA bias to prevent open-loop fault; Thevenin resistance <5 kΩ recommended. |
| VREF (8) | Bandgap reference decoupling | Internal 1.25 V reference node; requires ≥0.1 µF bypass to SGND for noise immunity and loop stability. |
| SENSE+ (9) | Current sense inverting input | Connected to high-side (positive DC) of sense resistor; common-mode range up to 60 V enables direct input-rail sensing. |
| SENSE– (10) | Current sense noninverting input | Connected to low-side (negative DC) of sense resistor; differential input rejects common-mode noise and offsets. |
| RUN/SHDN (11) | Precision shutdown enable | 1.15–1.35 V rising threshold with 25 mV hysteresis; supports both logic-level disable and analog UVLO for supply sequencing. |
| PGND (12) | Power ground | Return for GATE driver and switch; must be low-impedance path to VIN decoupling cap to minimize switching noise injection. |
| GATE (13) | N-MOSFET gate driver output | 11–12 V on, 0.4–0.7 V off; 60–200 ns rise/fall times drive up to 10,000 pF, supporting high-current discrete FETs. |
| 12VIN (14) | Main supply input | –0.3 V to 20 V rating; powers internal circuitry and gate driver; requires ≥1 µF bypass to PGND. |
| SYNC (15) | Oscillator sync input | TTL-compatible; triggers internal one-shot to lower CT high-threshold to 2 V for synchronization; min pulse width 1 µs. |
| 5VREF (16) | 5 V reference output | 4.75–5.25 V, 65 mA short-circuit current; powers external timing, logic, or bias circuits; disabled during shutdown. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable average current limiting | Enables precise DC input current control (120 mV threshold) independent of ripple, preventing transformer/magnetic saturation in high-power boost stages. |
| User-adjustable slope compensation | Allows stable operation up to 90% duty cycle in continuous conduction mode without subharmonic oscillation or audible noise. |
| High-voltage current sense common mode (up to 60 V) | Permits direct high-side sensing on input rail, eliminating need for expensive isolated amplifiers or complex blanking circuitry. |
| 5 V reference with 10 mA load capability | Provides regulated local bias for timing resistors, sync circuits, and auxiliary logic - reducing BOM count and layout complexity. |
| Soft start gated by UVLO and shutdown | Ensures controlled output voltage ramp after cold start or brownout recovery, preventing inrush current damage to FETs and output capacitors. |
Applications
| Industrial Power Supplies | Automotive DC/DC Conversion |
|---|---|
Use Scenario: 12 V to 48 V boost converter in factory automation PLCs requiring 250 W sustained output with thermal derating. IC Role / Device Role / Timing Role: Primary current-mode controller managing N-channel MOSFET switching, average current limiting, and soft-start sequencing. Use Value: 120 mV average current limit threshold ensures consistent 5.2 A input current limit across temperature, protecting upstream 12 V bus and batteries. | Use Scenario: Lead-acid battery backup system in commercial vehicles, boosting 12–16 V nominal to stable 48 V for camera and radar modules. IC Role / Device Role / Timing Role: High-reliability boost controller with undervoltage lockout (8.2–9.75 V falling threshold) and precision RUN/SHDN sequencing. Use Value: 350 mV UVLO hysteresis prevents cycling during engine cranking transients; 1.25 V shutdown threshold enables accurate battery voltage monitoring. |
| Distributed Power Architectures | Heavy Equipment Power Systems |
Use Scenario: Mid-rail boost stage in telecom shelf, converting 12 V backplane to 48 V for remote radio units with strict EMI limits. IC Role / Device Role / Timing Role: Synchronizable current-mode controller (up to 200 kHz) minimizing beat frequencies with adjacent converters. Use Value: SYNC pin accepts TTL-level clock signals, enabling deterministic switching alignment across multiple LT1680ISW#PBF units for reduced conducted EMI. | Use Scenario: Onboard power conversion in construction machinery, stepping up 24 V battery to 48 V for hydraulic control valves and sensors. IC Role / Device Role / Timing Role: Robust controller with 60 V sense common-mode range and –40°C to +85°C operation for harsh under-hood environments. Use Value: Direct high-side current sensing eliminates isolation barriers, reducing component count and failure points in vibration-prone mechanical enclosures. |
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 boost controller (4–36 V), integrated gate drivers, no external N-FET required; lacks 60 V sense common-mode range. | Best for lower-input-voltage, higher-efficiency synchronous designs where board space and efficiency outweigh cost and simplicity. | Select LTC3780EFE#PBF when synchronous rectification and integrated drivers are preferred over discrete N-FET flexibility and ultra-high input sense capability. |
| TPS40210DGQ | Current-mode boost controller (4.5–52 V), 1.23 V reference, 200 kHz max freq, but only 100 mV avg current limit threshold and no slope adjust pin. | Suitable for cost-sensitive industrial boost supplies where 120 mV precision limit and adjustable slope are not required. | Choose TPS40210DGQ for simpler, lower-cost implementations where full LT1680ISW#PBF feature set (e.g., SL/ADJ, 5VREF load drive) is unnecessary. |
Compared with LTC3780EFE#PBF and TPS40210DGQ, the LT1680ISW#PBF uniquely combines 60 V current sense common-mode range, user-adjustable slope compensation, and a dedicated 5 V reference output with 10 mA drive - making it optimal for high-reliability, high-input-voltage boost systems requiring design flexibility and robust sequencing.
Availability
LT1680ISW#PBF is available at Aetrix Electronics and suitable for industrial power supplies, automotive DC/DC conversion, and distributed power architectures requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1680ISW#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 technologies, serving industrial, automotive, communications, and healthcare markets.
The LT1680ISW#PBF belongs to ADI's legacy Linear Technology high-power DC/DC controller product line, designed specifically for rugged, high-efficiency boost converters in demanding industrial and transportation applications.
FAQ
What is the maximum duty cycle supported by the LT1680ISW#PBF?
The LT1680ISW#PBF supports up to 90% duty cycle when used with user-adjustable slope compensation via the SL/ADJ pin. This is enabled by its internal slope compensation ramp and external adjustment capability, which stabilizes current-mode control in continuous conduction mode. The minimum off-time (~1 µs) and oscillator architecture ensure switch protection even at high duty cycles. Designers must select inductance and RSENSE per the slope compensation equations in the datasheet to maintain stability.
How does the average current limit function work in the LT1680ISW#PBF?
The LT1680ISW#PBF implements average current limiting using an external capacitor on the IAVG pin (typically 220 pF to VC) forming a single-pole integrator with the pin's 50 kΩ output impedance. When the averaged sense amplifier output exceeds 120 mV (typical), the current comparator threshold is clamped, forcing current limiting independent of ripple. Shorting IAVG to SGND disables this function. This scheme avoids duty-cycle-dependent errors seen in peak-only limiting.
Can the LT1680ISW#PBF operate with a 24 V input and synchronize to an external 150 kHz clock?
Yes, the LT1680ISW#PBF supports 24 V input operation within its 12VIN pin rating (–0.3 V to 20 V), and its SYNC pin accepts TTL-level signals up to 200 kHz - including 150 kHz. The SYNC input triggers an internal one-shot that lowers the CT pin high threshold to 2 V for synchronization. Minimum on/off times of ≥1 µs must be maintained, and the SYNC signal should avoid duty cycles near 10% or 90% at 100 kHz to ensure reliable locking.
What is the purpose of the 5VREF pin on the LT1680ISW#PBF, and how much current can it supply?
The 5VREF pin on the LT1680ISW#PBF provides a regulated 4.75–5.25 V output derived from the internal bandgap reference, used to power external timing components (RCT, CCT), logic, or bias circuits. It delivers up to 10 mA DC (20 mA pulsed) load current, with 45 mA short-circuit current. The output is disabled during shutdown, and ≥1 µF bypass capacitance to SGND is required for stability and noise rejection.
How does the RUN/SHDN pin function in the LT1680ISW#PBF, and what is its threshold accuracy?
The RUN/SHDN pin on the LT1680ISW#PBF provides precision enable/disable control with a bandgap-referenced threshold of 1.15–1.35 V (typical 1.25 V) and 25 mV hysteresis. When pulled above threshold, the IC enables all functions; below threshold, it enters low-current shutdown (<250 µA). This pin supports both logic-level control and analog UVLO monitoring - e.g., a resistor divider from 12VIN can sequence startup at ~9 V, preventing inrush before supply stabilization.
LT1680ISW#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- 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:
- Surface Mount
- Supplier Device Package:
- 16-SO
LT1680ISW#PBF FAQ
1.How can I place an order for LT1680ISW#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1680ISW#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 LT1680ISW#PBF reliable?
The price and inventory of LT1680ISW#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1680ISW#PBF is usually 5 days.
3.What payment methods are accepted for LT1680ISW#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1680ISW#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1680ISW#PBF?
LT1680ISW#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1680ISW#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 LT1680ISW#PBF?
For technical support, including LT1680ISW#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1680ISW#PBF requirements.
6.How does Aetrix verify that LT1680ISW#PBF is sourced from the original manufacturer or authorized distributors?
All LT1680ISW#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 LT1680ISW#PBF meets industry standards.
7.What is the process for return or replacement of LT1680ISW#PBF?
All LT1680ISW#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1680ISW#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 LT1680ISW#PBF part is unused and in its original packaging.
Return procedure for LT1680ISW#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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