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Analog Devices Inc. LTC3403EDD#PBF
- Part No.:
- LTC3403EDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3403EDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 600MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:109
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Product details
Overview
LTC3403EDD#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency monolithic synchronous step-down regulator with integrated bypass P-channel MOSFET, optimized for WCDMA power amplifier supply. It delivers up to 600mA output current, operates from 2.5V to 5V input, supports dynamically programmable output voltage (0.3V–3.5V via REF pin), and achieves up to 96% efficiency at 1.5MHz switching frequency in mobile RF PA applications.
For engineers reviewing the LTC3403EDD#PBF datasheet, LTC3403EDD#PBF pinout, LTC3403EDD#PBF application, or LTC3403EDD#PBF equivalent, key selection considerations include its Burst Mode® quiescent current (20µA), 100% duty-cycle dropout operation, internal bypass FET RDS(ON) ≤ 0.20Ω (DD package), forced continuous mode for fast VOUT transient response, and 8-lead 3mm × 3mm DFN thermal performance (θJA = 43°C/W).
Technical Context
The LTC3403EDD#PBF employs constant-frequency current-mode control with internal P-channel main switch, N-channel synchronous rectifier, and dedicated bypass P-channel FET. Its REF pin sets VOUT = 3 × VREF, and when VREF > 1.2V, the bypass FET activates to short VIN to VOUT, eliminating inductor loss during high-VOUT operation.
Burst Mode® operation reduces quiescent current to 20µA by intermittently enabling switching cycles based on load demand, while forced continuous mode (MODE = VIN) ensures rapid output response to dynamic REF commands-critical for WCDMA PA envelope tracking. Slope compensation is internally managed to maintain stable peak current control across all duty cycles.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 5V - supports single-cell Li-ion battery operation with margin for voltage sag and ripple. |
| Output Current | 600mA - sufficient for WCDMA PA bias rails; peak inductor current rated to 1.25A. |
| Switching Frequency | 1.5MHz (typ) - enables use of compact 2.2µH inductors and ceramic capacitors without compromising transient response. |
| Quiescent Current | 20µA in Burst Mode® - extends battery life in standby/idle states of wireless modems and cell phones. |
| Bypass FET RDS(ON) | ≤ 0.20Ω (DD package, 100mA, 3V VIN) - minimizes conduction loss when VOUT > 3.6V, enabling near-lossless high-voltage PA supply. |
| Efficiency | Up to 96% - achieved via synchronous rectification and no external Schottky diode requirement. |
| Duty Cycle | 100% - supports low-dropout operation down to VOUT ≈ VIN − ILOAD × RDS(ON), critical for battery-end-of-life conditions. |
Pinout & Package
Package: 8-lead 3mm × 3mm plastic DFN with exposed pad (Pin 9), thermally connected to GND. θJA = 43°C/W, θJC = 3°C/W. Exposed pad must be soldered to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GDR (Pin 1) | External P-MOSFET gate driver | Drives optional external high-current P-channel FET in parallel with internal bypass FET for enhanced current capability. |
| VIN (Pin 2) | Main power input | Requires ≥10µF ceramic decoupling close to pin; absolute max DC voltage = 5.5V. |
| GND (Pin 3) | Power and signal reference | Common return for VIN, SW, RUN, MODE, REF, VOUT; connects to exposed pad (Pin 9). |
| SW (Pin 4) | Internal switch node | Connects drains of main P-FET and synchronous N-FET; drives external inductor; voltage swings from GND to VIN. |
| RUN (Pin 5) | Enable/shutdown control | Logic-high (>1.5V) enables regulation; logic-low (<0.3V) disables all circuitry, drawing <1µA. |
| MODE (Pin 6) | Operating mode select | Tied to VIN → forced continuous mode; grounded → Burst Mode®; floating not allowed. |
| REF (Pin 7) | Output voltage programming input | VOUT = 3 × VREF; range 0.1V–1.167V sets 0.3V–3.5V output; >1.2V triggers bypass FET activation. |
| VOUT (Pin 8) | Feedback and bypass FET drain | Internally divided by 3× resistive divider for EA comparison; also node where bypass FET connects to output rail. |
Key Features
| Feature | Design Value |
|---|---|
| Dynamically adjustable output | VOUT programmable from 0.3V to 3.5V via analog REF voltage - enables real-time PA bias optimization in envelope-tracking architectures. |
| Integrated bypass P-FET | RDS(ON) ≤ 0.20Ω (DD package) eliminates inductor loss when VOUT > 3.6V - improves efficiency by >5% in high-VOUT WCDMA PA modes. |
| Burst Mode® operation | 20µA quiescent current with automatic burst sleep/wake - extends standby time in intermittent-data wireless modems without sacrificing startup speed. |
| No external Schottky diode required | Internal synchronous N-channel rectifier replaces lossy external diode - reduces board area, BOM count, and thermal stress in space-constrained mobile designs. |
| 100% duty cycle dropout | Maintains regulation down to VOUT ≈ VIN - preserves PA functionality as battery voltage declines below nominal, extending usable runtime. |
| Fast transient response in forced mode | Continuous switching enables sub-µs VOUT recovery to REF changes - meets stringent WCDMA PA envelope slew rate requirements (e.g., >0.2V/µs). |
Applications
| WCDMA Power Amplifier Supply | Wireless Modem Bias Rail |
|---|---|
Use Scenario: Supplies dynamic bias voltage to WCDMA power amplifier during transmit bursts, tracking envelope variations in real time. IC Role / Device Role / Timing Role: Synchronous buck regulator with programmable output and bypass FET - acts as precision, low-noise, high-efficiency PA voltage source. Use Value: Enables >96% efficiency at 3.5V output and 600mA load, reducing thermal load and extending battery life in handheld transceivers. |
Use Scenario: Powers baseband processor and RF front-end in portable LTE/WiMAX modems requiring low-quiescent, fast-response DC-DC conversion. IC Role / Device Role / Timing Role: Primary system regulator delivering stable 1.2V–2.5V rails with Burst Mode® for ultra-low idle power. Use Value: 20µA operating current and <1µA shutdown draw enable multi-week standby without recharge in always-connected IoT modems. |
| Li-Ion Powered Portable Devices | Envelope Tracking Power Supply |
Use Scenario: Regulates core voltage for microcontrollers and sensors in battery-powered medical wearables and handheld instruments. IC Role / Device Role / Timing Role: High-efficiency step-down converter supporting 2.5V–5V input range - serves as main system power source. Use Value: 1.5MHz fixed frequency allows miniature 2.2µH inductor and 4.7µF ceramic output capacitor, minimizing footprint in compact PCB layouts. |
Use Scenario: Generates rapidly varying PA supply voltage synchronized to RF envelope signal in advanced cellular base stations and repeaters. IC Role / Device Role / Timing Role: Fast-response buck regulator with REF-driven VOUT modulation - functions as analog-controlled power stage. Use Value: Forced continuous mode enables <2µs load-step recovery and ±10mV output ripple, meeting EVM and ACLR linearity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#PBF | Higher input range (3V–42V), higher IOUT (3.5A), Silent Switcher® architecture; no integrated bypass FET. | Designed for industrial/high-voltage systems; lacks REF-based dynamic VOUT programming and bypass FET for WCDMA PA optimization. | Select when wide VIN or high current is needed; avoid for low-VIN mobile PA where LTC3403EDD#PBF's 2.5V start-up and bypass FET provide superior efficiency. |
| TPS62130ARGTR | 3V–17V input, 3A output, 2.5MHz switching, no bypass FET; quiescent current 17µA (slightly lower than LTC3403EDD#PBF). | Optimized for general-purpose portable systems; lacks REF pin for analog VOUT programming and 100% duty cycle dropout. | Prefer for cost-sensitive, non-PA applications needing higher current; LTC3403EDD#PBF remains superior for WCDMA envelope tracking due to REF interface and bypass FET. |
Compared with LT8610EMSE#PBF and TPS62130ARGTR, the LTC3403EDD#PBF uniquely combines REF-based analog VOUT programming, integrated bypass FET for >3.6V operation, 2.5V minimum input, and 100% duty cycle - making it irreplaceable for WCDMA/LTE PA bias where dynamic efficiency and low-VIN headroom are critical.
Availability
LTC3403EDD#PBF is available at Aetrix Electronics and suitable for WCDMA power amplifier design, wireless modem development, and Li-ion powered portable instrumentation requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3403EDD#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 LTC3403EDD#PBF belongs to Linear's high-efficiency DC/DC converter product line, specifically engineered for battery-powered RF power amplifier applications demanding dynamic voltage scaling, ultra-low quiescent current, and seamless dropout operation.
FAQ
What is the minimum input voltage required for LTC3403EDD#PBF to regulate?
The LTC3403EDD#PBF guarantees operation down to 2.5V input voltage. Below this, regulation may fail or output current capability drops significantly. At 2.5V input, maximum output current is reduced - e.g., ~400mA at VOUT = 1.8V per Figure 2 in the datasheet. The device enters 100% duty cycle dropout when VREF would command VOUT > VIN, maintaining regulation until VOUT ≈ VIN − ILOAD × RDS(ON).
How does the bypass P-channel FET in LTC3403EDD#PBF improve efficiency?
The bypass P-FET in LTC3403EDD#PBF activates when VREF > 1.2V (i.e., VOUT > 3.6V), directly connecting VIN to VOUT and bypassing the inductor and main switch. With RDS(ON) ≤ 0.20Ω in the DD package, conduction loss is drastically reduced versus standard buck operation - improving full-load efficiency by 4–6% in high-VOUT WCDMA PA modes compared to regulators without this feature.
Can LTC3403EDD#PBF be used with ceramic output capacitors?
Yes, LTC3403EDD#PBF is fully compatible with ceramic output capacitors. Its current-mode control loop does not rely on capacitor ESR for stability, enabling use of low-ESR X5R/X7R ceramics (e.g., 4.7µF in Figure 1a). This yields minimal output ripple (<15mV typical) and compact layout. Avoid Y5V dielectrics due to severe capacitance loss under bias and temperature.
What is the purpose of the GDR pin on LTC3403EDD#PBF?
The GDR (Gate Driver) pin on LTC3403EDD#PBF drives the gate of an optional external P-channel MOSFET connected between VIN and VOUT. This extends current capability beyond the internal 600mA limit and further reduces total RDS(ON) in high-current or high-efficiency PA applications. The external FET operates in parallel with the internal bypass FET when VREF > 1.2V.
How does Burst Mode® operation affect transient response in LTC3403EDD#PBF?
In Burst Mode®, LTC3403EDD#PBF disables switching between load pulses to reduce quiescent current to 20µA, but this introduces latency in load-step response - output voltage may droop 20–50mV before regulation resumes. For applications requiring fast transient recovery (e.g., WCDMA envelope tracking), forced continuous mode (MODE = VIN) must be used, ensuring immediate response with <2µs recovery time.
LTC3403EDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 5V
- Voltage - Output (Min/Fixed):
- 0.3V
- Voltage - Output (Max):
- 3.5V
- Current - Output:
- 600mA
- Frequency - Switching:
- 1.5MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x3)
LTC3403EDD#PBF FAQ
1.How can I place an order for LTC3403EDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3403EDD#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 LTC3403EDD#PBF reliable?
The price and inventory of LTC3403EDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3403EDD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3403EDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3403EDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3403EDD#PBF?
LTC3403EDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3403EDD#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 LTC3403EDD#PBF?
For technical support, including LTC3403EDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3403EDD#PBF requirements.
6.How does Aetrix verify that LTC3403EDD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3403EDD#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 LTC3403EDD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3403EDD#PBF?
All LTC3403EDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3403EDD#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 LTC3403EDD#PBF part is unused and in its original packaging.
Return procedure for LTC3403EDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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