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Analog Devices Inc. LT8697IUDD#PBF
- Part No.:
- LT8697IUDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LT8697IUDD#PBF.pdf
- Description:
- IC REG CONV USB 1OUT 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,364
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Product details
Overview
LT8697IUDD#PBF from Analog Devices (formerly Linear Technology) is a 2 MHz synchronous step-down DC/DC converter optimized for 5 V USB power delivery with cable drop compensation. It delivers up to 2.5 A output current, supports 5 V to 42 V input range, maintains ±1.3% output voltage accuracy over temperature, and features programmable current limit and forced continuous mode for fast transient response in automotive and industrial USB applications.
For engineers reviewing the LT8697IUDD#PBF datasheet, LT8697IUDD#PBF pinout, LT8697IUDD#PBF application, or LT8697IUDD#PBF equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative options, and supply-chain support details specific to the –40°C to 125°C industrial-grade variant in 3 mm × 5 mm QFN.
Technical Context
The LT8697IUDD#PBF implements constant-frequency current-mode control with an adjustable oscillator (300 kHz–2.2 MHz) set via RT resistor. Its dual feedback architecture allows regulation either at the USB5V pin (for local 5 V output) or at the SYS pin (to enforce ≤5.8 V clamp during fault conditions), enabling safe cable drop compensation without external sensing wires.
It integrates top and bottom NMOS power switches (120 mΩ / 65 mΩ typical RDS(on)), supports forced continuous conduction mode (FCM) for sink capability and sub-100 ns minimum on-time (45 ns typ), and uses internal 0.97 V reference with 5× divider ratio for USB5V regulation-enabling precise 5 V output despite load-induced cable voltage drop.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5 V to 42 V - supports wide automotive battery transients and industrial 24 V/36 V rails without external pre-regulation. |
| Output Voltage Accuracy | ±1.3% over –40°C to 125°C - ensures stable 5 V USB compliance across full industrial temperature range. |
| Max Output Current | 2.5 A - sufficient for USB-C PD 5 V @ 2.4 A applications with margin for thermal derating in 3 mm × 5 mm QFN. |
| Switching Frequency | Adjustable 300 kHz to 2.2 MHz - enables EMI optimization and small external component selection (e.g., 3.3 µH inductor). |
| Cable Drop Compensation | Programmable via RCBL pin - compensates up to ~0.8 V drop at full load using resistor ratio, maintaining 5 V at remote USB socket. |
| Min On-Time | 45 ns - supports high VIN-to-VOUT ratios (e.g., 42 V → 5 V) at 2 MHz without pulse-skipping instability. |
| Thermal Rating | Junction temp: –40°C to 125°C - qualified for industrial environments; exposed pad reduces θJA to 46°C/W. |
Pinout & Package
LT8697IUDD#PBF is housed in a thermally enhanced 24-lead 3 mm × 5 mm plastic QFN package with exposed pad (Pin 25) soldered to PCB ground for low thermal resistance (θJA = 46°C/W, θJC = 5°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UV (Pin 4) | Enable / Input Undervoltage Lockout | Hysteretic enable threshold (0.94–1.06 V); allows programmable VIN shutdown via external resistor divider. |
| USB5V (Pin 20) | Main Output Voltage Sense & Regulation Node | Regulated to 5 V ±1.3%; sources current proportional to load for cable compensation; clamped to 9 V for ESD protection. |
| ISP / ISN (Pins 21/22) | Differential Current Sense Inputs | Monitor output current via external sense resistor (e.g., 20 mΩ); enable accurate programmable current limiting (2.9–6 A). |
| RCBL (Pin 23) | Cable Drop Compensation Programming | Sinks current proportional to (VISP–VISN); sets compensation gain via RCBL-to-GND resistor (e.g., 13.7 kΩ for 0.3 Ω cable). |
| ICTRL (Pin 24) | Current Limit Threshold Adjustment | Modulates VISP–VISN trip point from 4.5 mV to 51 mV; allows fine-tuning of output current limit independent of sense resistor. |
| PG (Pin 19) | Power Good Open-Drain Output | Asserts high when USB5V is within ±9% of 5 V and no faults exist; 40 µs delay ensures stable startup before system enable. |
| GND (Pin 25, Exposed Pad) | Primary Ground Reference & Thermal Path | Must be soldered to large PCB copper area; serves as return for PGND, INTVCC, and thermal dissipation path. |
Key Features
| Feature | Design Value |
|---|---|
| Forced Continuous Mode (FCM) | Enables output current sinking and eliminates discontinuous conduction, improving load-step transient response (<100 µs recovery) and ensuring stable 2 MHz operation down to zero load. |
| Dual Feedback Regulation | Allows regulation at USB5V pin (5 V target) or SYS pin (≤5.8 V clamp); prevents overvoltage during cable compensation faults or USB switch insertion. |
| Programmable Cable Drop Compensation | Compensates resistive losses in up to 3 m AWG 20 twisted-pair cables without Kelvin sensing-maintains 5 V ±25 mV at point-of-load under 2.1 A load. |
| Accurate Output Current Monitoring | Provides analog current monitor signal (IUSB5V) proportional to load current (57.5–62.5 µA per 40 mV sense voltage), enabling real-time system-level current telemetry. |
| Robust Protection Suite | Includes thermal shutdown, input UVLO, PG fault detection, and internal 5.8 V SYS clamp-eliminates need for external USB power switches or overvoltage protectors. |
Applications
| Automotive USB Charging Ports | Industrial USB Hub Power |
|---|---|
|
Use Scenario: Powering USB peripherals in vehicle cabins where long wiring harnesses (≥2 m) cause >300 mV voltage drop at 2.1 A. IC Role / Device Role / Timing Role: Primary 5 V buck regulator with active cable compensation; regulates at USB5V pin while dynamically boosting VOUT based on sensed load current. Use Value: Maintains 5.00 V ±25 mV at USB socket despite 0.3 Ω cable resistance, meeting USB BC1.2 specification without external feedback routing. |
Use Scenario: Supplying multiple downstream USB ports in factory automation gateways with shared 24 V rail and variable load profiles. IC Role / Device Role / Timing Role: High-efficiency, thermally robust 5 V source with programmable current limit (2.1 A) and PG signaling for host controller coordination. Use Value: Delivers 93% efficiency at 2.1 A from 12 V input and supports latch-off fault handling via ICTRL/PG interface-reducing BOM count vs discrete protection ICs. |
| Precision 5 V Instrumentation Supply | USB-C Power Delivery Companion |
|
Use Scenario: Providing ultra-stable 5 V bias for ADC references, sensor interfaces, or FPGA configuration in test equipment. IC Role / Device Role / Timing Role: Low-noise, high-PSRR 5 V regulator with ±1.3% accuracy over –40°C to 125°C and <25 mV line regulation (6–42 V). Use Value: Eliminates need for post-regulation LDOs by delivering lab-grade 5 V stability directly from unregulated industrial input rails. |
Use Scenario: Backing 5 V VBUS in USB-C PD sink designs where main PD controller handles higher voltages but requires robust 5 V fallback. IC Role / Device Role / Timing Role: Standby 5 V source with fast turn-on (<1 ms), FCM-enabled sink capability, and auto-retry via TR/SS soft-start control. Use Value: Enables seamless transition from PD negotiation to native 5 V delivery with <100 µs load-step response-critical for plug-in detection and enumeration timing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8640SIV#PBF | Wider input range (3.4–65 V), lower quiescent current (2.5 µA), but no cable drop compensation or USB5V-specific feedback architecture. | Lacks integrated RCBL/USB5V compensation loop; requires external circuitry for remote 5 V regulation. | Choose for ultra-low-IQ or >42 V input needs; avoid when cable compensation is mandatory. |
| MPQ4420AGU-AEC1-P | Automotive-grade (AEC-Q100), 36 V max input, 2 A output, no dedicated USB5V pin or cable compensation programming. | No built-in current monitor or programmable current limit; relies on external OCP solutions. | Select for cost-sensitive automotive body electronics where USB-specific features are unnecessary. |
Compared with LT8697IUDD#PBF, LT8640SIV#PBF offers broader input voltage support but sacrifices USB-targeted features like cable drop compensation and dual-feedback regulation, while MPQ4420AGU-AEC1-P provides AEC-Q100 qualification at lower current and without integrated current monitoring-making LT8697IUDD#PBF uniquely suited for precision 5 V USB power with long-cable integrity.
Availability
LT8697IUDD#PBF is available at Aetrix Electronics and suitable for automotive USB charging ports, industrial USB hub power supplies, precision 5 V instrumentation supplies, and USB-C power delivery companion circuits requiring stable component supply across extended temperature ranges.
Supply support for LT8697IUDD#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 acquired Linear Technology in 2017 and maintains its legacy of high-performance power management ICs with rigorous automotive and industrial qualification standards.
The LT8697IUDD#PBF belongs to Linear's monolithic synchronous buck regulator product line, designed specifically for USB-compliant 5 V power delivery with cable compensation in harsh environments where input transients and thermal constraints demand robust integration.
FAQ
What is the operating temperature range for the LT8697IUDD#PBF?
The LT8697IUDD#PBF is rated for junction temperatures from –40°C to 125°C and is specified for industrial applications. This grade guarantees full electrical performance-including ±1.3% output voltage accuracy and 2.5 A current capability-across that entire range, unlike the E-grade (0°C to 125°C) or H-grade (–40°C to 150°C) variants. Thermal derating begins above 125°C per manufacturer guidelines.
How does the LT8697IUDD#PBF implement cable drop compensation without Kelvin sensing?
The LT8697IUDD#PBF uses its RCBL pin to source current proportional to (VISP – VISN), which flows through RCDC to raise the USB5V node voltage. This creates a negative output impedance that offsets cable IR drop. The compensation gain is set by RCBL and RCDC resistor values-not measured cable resistance-so designers must calculate RCBL using the formula RCBL = 20.55 × RSENSE × RCDC / RCABLE.
Can the LT8697IUDD#PBF regulate output voltage at the remote load instead of at the IC?
No-the LT8697IUDD#PBF does not support true remote sensing. It regulates locally at the USB5V pin and *compensates* for cable drop by raising VOUT proportionally to load current. To maintain 5 V at the load, the designer must place RCDC between the output and USB5V pin and select RCBL to match the known cable resistance-effectively pre-biasing VOUT upward to counteract expected drop.
What is the purpose of the SYS pin on the LT8697IUDD#PBF?
The SYS pin on the LT8697IUDD#PBF serves two roles: (1) it acts as a secondary error amplifier input that clamps regulated output to ≤5.8 V during fault conditions, and (2) it supplies power to internal circuitry when biased ≥3.3 V-reducing VIN supply current and improving light-load efficiency. It must be connected to the output side of the inductor and bypassed with ≥47 µF capacitance.
Does the LT8697IUDD#PBF support synchronization to an external clock?
Yes-the LT8697IUDD#PBF accepts an external clock signal on the SYNC pin (Pin 1) to synchronize switching frequency from 300 kHz to 2.2 MHz. When synchronized, the device operates in forced continuous mode (FCM), enabling deterministic timing, reduced EMI, and improved transient response. If unused, SYNC must be tied to INTVCC-not left floating-to prevent noise coupling.
LT8697IUDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Converter, USB
- Voltage - Input:
- 5V ~ 42V
- Number of Outputs:
- 1
- Voltage - Output:
- 5V ~ 5.25V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (3x5)
LT8697IUDD#PBF FAQ
1.How can I place an order for LT8697IUDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8697IUDD#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 LT8697IUDD#PBF reliable?
The price and inventory of LT8697IUDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8697IUDD#PBF is usually 5 days.
3.What payment methods are accepted for LT8697IUDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8697IUDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8697IUDD#PBF?
LT8697IUDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8697IUDD#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 LT8697IUDD#PBF?
For technical support, including LT8697IUDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8697IUDD#PBF requirements.
6.How does Aetrix verify that LT8697IUDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT8697IUDD#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 LT8697IUDD#PBF meets industry standards.
7.What is the process for return or replacement of LT8697IUDD#PBF?
All LT8697IUDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8697IUDD#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 LT8697IUDD#PBF part is unused and in its original packaging.
Return procedure for LT8697IUDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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