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Analog Devices Inc. LTC3808EDE
- Part No.:
- LTC3808EDE
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LTC3808EDE.pdf
- Description:
- IC REG CTRLR BUCK 14-DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,951
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Product details
Overview
LTC3808EDE from Analog Devices (formerly Linear Technology) is a synchronous step-down DC/DC controller IC that drives external complementary P- and N-channel MOSFETs without requiring a current-sense resistor. It delivers 0.6V ±1.5% reference accuracy, supports 2.75V–9.8V input and 0.6V–VIN output ranges, operates at 550kHz (typical), and enables output voltage tracking for multi-rail power sequencing in portable computing systems.
For engineers reviewing the LTC3808EDE datasheet, LTC3808EDE pinout, LTC3808EDE application, or LTC3808EDE equivalent, key selection criteria include its no-RSENSE operation, spread spectrum EMI reduction, programmable peak current sense threshold via IPRG, true PLL synchronization (250–750kHz), and support for Burst Mode, pulse skipping, or forced continuous operation - all critical for battery-powered, noise-sensitive, and space-constrained designs.
Technical Context
The LTC3808EDE implements constant-frequency current-mode control using MOSFET VDS sensing to eliminate external sense resistors, improving efficiency and thermal performance. Its architecture integrates a precision 0.6V bandgap reference, error amplifier with ITH compensation node, and dual-gate drivers (TG/BG) with 40–50ns switching transitions.
It features a fully integrated phase-locked loop (PLL) with external synchronization capability (250–750kHz), spread spectrum modulation (460–635kHz), and three selectable light-load modes - Burst Mode (9µA shutdown IQ), pulse skipping, and forced continuous - each with distinct ripple, efficiency, and EMI trade-offs confirmed across load and temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.75V to 9.8V - supports single/dual Li-ion battery inputs and wide industrial supply rails. |
| Output Voltage Range | 0.6V to VIN - enables low-voltage core supplies (e.g., 1.2V, 1.8V) and dropout operation down to ~0.1V headroom. |
| Reference Voltage | 0.6V ±1.5% over –40°C to 85°C - ensures tight output regulation without external trimming. |
| Switching Frequency | 550kHz typical (480–600kHz range); programmable from 250kHz to 750kHz via PLLLPF/SYNC/MODE - balances efficiency vs. inductor/capacitor size. |
| Quiescent Current | 9µA in shutdown, 105–150µA in sleep mode - extends battery life in always-on portable devices. |
| Peak Gate Drive Current | 1A (TG/BG) - reliably switches high-side PMOS and low-side NMOS with fast rise/fall times (40–50ns). |
| Current Sense Threshold | Selectable: 85mV (IPRG = GND), 125mV (IPRG = float), or 204mV (IPRG = VIN) - optimizes MOSFET RDS(on) utilization and transient response. |
Pinout & Package
Tiny thermally enhanced 14-lead (4mm × 3mm) plastic DFN package with exposed pad (Pin 15 = GND), rated for –40°C to 85°C operating temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PLLLPF (Pin 1) | Frequency set / PLL low-pass filter | Configures oscillator frequency (300/550/750kHz) or sets PLL loop filter when synchronized externally. |
| SYNC/MODE (Pin 2) | Mode select / sync input / auxiliary feedback | Controls Burst Mode/pulse skipping/forced continuous; enables PLL sync (250–750kHz) and spread spectrum modulation. |
| TRACK/SS (Pin 3) | Tracking input / external soft-start | Enables output voltage ramp tracking of external rail or programmable soft-start via capacitor to GND. |
| PGOOD (Pin 4) | Open-drain power-good monitor | Asserts low when VFB deviates >±10% from 0.6V - signals valid output for system enable sequencing. |
| VFB (Pin 5) | Feedback voltage input | Compares divided output voltage against 0.6V reference; input bias <50nA minimizes divider error. |
| ITH (Pin 6) | Error amplifier output / current limit threshold | Sets peak inductor current; nominal 0.7–2.0V range enables precise current-mode loop compensation. |
| RUN (Pin 7) | Enable control input | Shuts down IC below 1.1V threshold; draws only 9µA in shutdown - ideal for system-level power management. |
| IPRG (Pin 8) | Current sense threshold select | Three-state pin (GND/float/VIN) selects 85/125/204mV max ΔVSENSE - adapts to MOSFET RDS(on) or sense resistor value. |
| BG (Pin 9) | Bottom gate driver output | Drives NMOS source-follower configuration; swing from GND to SENSE+ ensures full turn-on. |
| TG (Pin 10) | Top gate driver output | Drives PMOS high-side switch; rail-to-rail swing (GND to SENSE+) enables efficient high-side drive. |
| SENSE+ (Pin 11) | Current comparator positive input | Connects to PMOS source (no-RSENSE) or sense resistor top - powers gate drivers and senses current path. |
| VIN (Pin 12) | Signal power supply | Powers internal circuitry (excluding gate drivers); requires RC filtering to suppress switching noise coupling. |
| SENSE– (Pin 13) | Current comparator negative input | Connects to SW node (no-RSENSE) or sense resistor bottom - completes differential current sensing path. |
| SW (Pin 14) | Switch node connection | Connects to PMOS drain, NMOS drain, and inductor - serves as current sense reference and reverse-current detection point. |
| GND (Pin 15) | Ground reference / thermal pad | Common return for logic, gate drivers, and current comparator; exposed pad must be soldered for thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| No-RSENSE operation | Eliminates power loss and board area of external current-sense resistor by using MOSFET VDS sensing - improves efficiency up to 3% at 2A. |
| Spread spectrum modulation | Reduces EMI peak emissions by spreading 550kHz fundamental across 460–635kHz - meets Class B CISPR-22 without added shielding. |
| True PLL synchronization | Locks internal oscillator to external clock (250–750kHz) with ±100ppm accuracy - eliminates beat frequencies in multi-regulator systems. |
| Programmable output tracking | Enables precise power-rail sequencing (e.g., VDDIO before VDDCORE) using external resistor dividers on TRACK/SS - prevents latch-up in FPGAs and processors. |
| 100% duty cycle dropout | Maintains regulation down to VIN–VOUT ≈ 0.1V by holding TG high - extends runtime in battery-powered systems near end-of-discharge. |
| Output overvoltage protection | Shuts off TG and turns on BG when VFB exceeds 0.68V (±13.3%) - protects downstream ICs from transient overshoot during load dump or startup. |
Applications
| Mobile Computing Power Sequencing | Low-EMI Industrial DC-DC Converter |
|---|---|
Use Scenario: Dual-rail power supply for ARM-based tablet SoC requiring VDDIO (3.3V) to ramp before VDDCORE (1.2V) with <10ms delay. IC Role / Device Role / Timing Role: LTC3808EDE acts as master controller for VDDCORE, tracking VDDIO via resistor divider on TRACK/SS pin to enforce strict sequencing order. Use Value: Prevents FPGA configuration failure and processor latch-up by ensuring correct rail activation sequence without external sequencer IC. | Use Scenario: 5V-to-3.3V point-of-load converter in factory automation PLC with strict EMC requirements. IC Role / Device Role / Timing Role: LTC3808EDE operates in spread spectrum mode (460–635kHz) with PLL locked to system clock, suppressing narrowband EMI peaks. Use Value: Achieves CISPR-22 Class B compliance without ferrite beads or metal shielding - reduces BOM cost and board area by 18%. |
| Battery-Powered Medical Instrument | Distributed Telecom Power System |
Use Scenario: Portable ultrasound device powered by two-cell Li-ion (6.0–8.4V) requiring 1.8V/2A for analog front-end with minimal heat generation. IC Role / Device Role / Timing Role: LTC3808EDE controls external PMOS/NMOS pair in Burst Mode, delivering >92% efficiency at 10mA load and <9µA shutdown IQ. Use Value: Extends battery runtime by 40% versus fixed-frequency controllers and enables instant wake-from-sleep with internal 1ms soft-start. | Use Scenario: Intermediate bus converter (12V-to-5V) in 48V telecom shelf supplying multiple distributed loads. IC Role / Device Role / Timing Role: LTC3808EDE synchronizes to central 500kHz clock via SYNC/MODE pin, eliminating beat frequencies across 12 parallel converters. Use Value: Reduces conducted EMI by 15dB and simplifies thermal management through deterministic switching alignment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2315DJ-LF-Z | Integrated MOSFETs (no external FETs), fixed 500kHz frequency, no PLL or spread spectrum | Lower component count but limited to ≤3A output; unsuitable for high-efficiency/no-RSENSE or EMI-critical designs | Choose MP2315 for cost-sensitive, lower-current (<2.5A), non-EMI-constrained applications where integration outweighs flexibility. |
| LTC3850EGN#PBF | Wider VIN (4.5–38V), higher VOUT (0.8–30V), dual-phase capable, includes current sharing | Designed for high-voltage industrial/automotive rails; incompatible with sub-3V inputs or Li-ion battery direct feed | Choose LTC3850 for 12V/24V intermediate bus or multi-phase CPU VRMs - not a drop-in replacement for LTC3808EDE's low-VIN domain. |
Compared with MP2315DJ-LF-Z and LTC3850EGN#PBF, the LTC3808EDE uniquely combines no-RSENSE operation, 2.75V minimum input, programmable spread spectrum, and true PLL synchronization - making it optimal for compact, battery-powered, and EMI-sensitive 3–9V systems where external FET selection and precise timing control are required.
Availability
LTC3808EDE is available at Aetrix Electronics and suitable for mobile computing power sequencing, low-EMI industrial DC-DC conversion, battery-powered medical instrumentation, distributed telecom power systems, and portable instrument power management requiring stable component supply and long-term lifecycle support.
Supply support for LTC3808EDE 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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3808EDE belongs to Linear's high-efficiency, low-EMI synchronous controller product line, designed specifically for battery-powered and noise-sensitive applications requiring precise rail sequencing, wide input range, and flexible light-load operation.
FAQ
What is the maximum supported input voltage for the LTC3808EDE?
The LTC3808EDE has an absolute maximum input voltage rating of 10V, with guaranteed operation across 2.75V to 9.8V. Exceeding 10V may damage the IC. The undervoltage lockout activates at 2.25V (falling) and 2.45V (rising), ensuring reliable start-up and brownout protection. This range makes the LTC3808EDE ideal for dual-cell Li-ion (up to 8.4V) and regulated 5V/9V industrial supplies.
Does the LTC3808EDE require an external current-sense resistor?
No, the LTC3808EDE does not require an external current-sense resistor. It uses MOSFET VDS sensing between SENSE+ and SENSE–/SW pins to measure inductor current - a feature branded "No RSENSE" by Linear Technology. This eliminates power loss and PCB area associated with sense resistors. However, an optional sense resistor can be used if preferred, with IPRG pin selecting appropriate threshold (85/125/204mV).
How does the LTC3808EDE achieve low EMI performance?
The LTC3808EDE achieves low EMI through three integrated techniques: (1) spread spectrum modulation (460–635kHz), which smears spectral energy; (2) true PLL synchronization (250–750kHz), eliminating beat frequencies in multi-regulator systems; and (3) constant-frequency current-mode control with fast, controlled gate drive edges (40–50ns). These features collectively reduce peak radiated emissions by up to 10dB compared to fixed-frequency alternatives.
What are the light-load operation modes supported by the LTC3808EDE?
The LTC3808EDE supports three configurable light-load modes via the SYNC/MODE pin: Burst Mode (highest efficiency, audible noise possible), pulse skipping (low ripple, moderate efficiency), and forced continuous conduction (lowest ripple, lowest efficiency). Burst Mode reduces quiescent current to 105–150µA and enables >90% efficiency at 10mA load - critical for extending battery life in portable devices powered by the LTC3808EDE.
Can the LTC3808EDE be used for output voltage tracking in multi-rail systems?
Yes, the LTC3808EDE supports precise output voltage tracking via the TRACK/SS pin. When an external voltage (e.g., from another regulator) is applied through a resistor divider to TRACK/SS, the LTC3808EDE ramps its output to match that voltage during startup. This enables coordinated sequencing of multiple rails - for example, ensuring memory I/O voltage rises before core voltage in processors - without requiring external sequencer ICs or complex timing circuits.
LTC3808EDE Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 2.75V ~ 9.8V
- Frequency - Switching:
- 250kHz ~ 750kHz
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DFN (4x3)
LTC3808EDE FAQ
1.How can I place an order for LTC3808EDE through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3808EDE 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 LTC3808EDE reliable?
The price and inventory of LTC3808EDE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3808EDE is usually 5 days.
3.What payment methods are accepted for LTC3808EDE?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3808EDE transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3808EDE?
LTC3808EDE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3808EDE 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 LTC3808EDE?
For technical support, including LTC3808EDE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3808EDE requirements.
6.How does Aetrix verify that LTC3808EDE is sourced from the original manufacturer or authorized distributors?
All LTC3808EDE 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 LTC3808EDE meets industry standards.
7.What is the process for return or replacement of LTC3808EDE?
All LTC3808EDE units undergo pre-shipment inspection (PSI). If there is an issue with LTC3808EDE, 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 LTC3808EDE part is unused and in its original packaging.
Return procedure for LTC3808EDE:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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