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Analog Devices Inc. LTC3403EDD#TRPBF
- Part No.:
- LTC3403EDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3403EDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 600MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,485
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Product details
Overview
LTC3403EDD#TRPBF 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 from 0.3V to 3.5V via REF pin, and achieves up to 96% efficiency in forced continuous mode at 1.5MHz switching frequency - enabling compact Li-ion-powered RF PA biasing.
For engineers reviewing the LTC3403EDD#TRPBF datasheet, LTC3403EDD#TRPBF pinout, LTC3403EDD#TRPBF application, or LTC3403EDD#TRPBF equivalent, key selection considerations include its Burst Mode® quiescent current (20µA), 100% duty-cycle dropout operation, internal RDS(ON) values (0.4Ω main P-FET, 0.2Ω bypass P-FET in DD package), and compatibility with ceramic input/output capacitors in space-constrained mobile RF designs.
Technical Context
The LTC3403EDD#TRPBF employs a constant-frequency, current-mode control architecture with internal P-channel main switch, N-channel synchronous switch, and dedicated bypass P-channel FET. Its peak inductor current is regulated by an error amplifier driving a current comparator, while slope compensation prevents subharmonic oscillation above 40% duty cycle - enhanced by a proprietary scheme that preserves maximum peak current across all duty cycles.
Burst Mode® operation modulates switching intermittently to maintain 20µA quiescent current at light loads, while forced continuous mode (MODE = VIN) enables fast transient response for dynamic RF PA voltage scaling. The REF pin sets VOUT = 3 × VREF, and when VREF > 1.2V, the bypass FET activates to short VIN to VOUT, eliminating inductor loss and enabling ultra-low-dropout operation below 3.6V output.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 5V - supports single-cell Li-ion battery operation with headroom for voltage sag. |
| Output Current | 600mA continuous - sufficient for WCDMA/UMTS power amplifier bias without external boost. |
| Switching Frequency | 1.5MHz (typ) - enables use of small 2.2µH inductors and 4.7µF ceramic output capacitors. |
| Quiescent Current | 20µA in Burst Mode®, <1µA in shutdown - extends battery life during idle RF transmit states. |
| RDS(ON) (Main P-FET) | 0.4Ω (DD package) - limits conduction loss in dropout mode at low VIN (e.g., 2.7V). |
| RDS(ON) (Bypass P-FET) | 0.20Ω (DD package, IOUT = 100mA, VIN = 3V) - reduces voltage drop when VOUT ≥ 3.6V, improving efficiency in high-VOUT PA modes. |
| Output Voltage Range | 0.3V to 3.5V (programmed via REF) - matches dynamic envelope tracking requirements of modern RF PAs. |
| Efficiency | Up to 96% at 600mA, VIN = 3.6V, VOUT = 1.8V - minimizes thermal load in sealed handheld enclosures. |
Pinout & Package
Package: 8-lead 3mm × 3mm DFN with exposed pad (Pin 9), thermally connected to GND. Pin pitch: 0.5mm. RoHS-compliant, moisture sensitivity level (MSL) 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 8) | Output feedback node | Internally divided by 3× resistive divider; connects to drain of bypass P-FET - critical for accurate VREF-to-VOUT scaling and bypass activation threshold. |
| REF (Pin 7) | External reference input | Sets VOUT = 3 × VREF; triggers bypass FET turn-on when VREF > 1.2V - enables dynamic PA voltage programming via DAC. |
| MODE (Pin 6) | Operating mode select | Logic-high (tied to VIN) enables forced continuous mode for fast transient response; logic-low enables Burst Mode® for ultra-low IQ. |
| RUN (Pin 5) | Enable/shutdown control | Threshold 0.3V–1.5V; <1µA shutdown current - allows system-level power sequencing and deep-sleep control. |
| SW (Pin 4) | Switch node | Connects to inductor; carries high di/dt square wave - requires tight layout with low-inductance path to minimize EMI and voltage spikes. |
| GND (Pin 3) | Power and signal ground | Reference for all internal circuits; must be connected to exposed pad (Pin 9) for thermal and electrical integrity. |
| VIN (Pin 2) | Main power input | Supplies internal regulators and switches; requires ≥10µF ceramic decoupling close to pin to suppress switching noise. |
| GDR (Pin 1) | External gate driver | Drives optional external P-channel MOSFET for higher current or lower RDS(ON) - not used in standard WCDMA PA configuration. |
Key Features
| Feature | Design Value |
|---|---|
| Dynamically adjustable output (0.3V–3.5V) | Enables real-time envelope tracking of WCDMA/UMTS power amplifiers via DAC-driven REF pin, reducing PA power dissipation. |
| Integrated bypass P-channel MOSFET | Activates when VREF > 1.2V (VOUT > 3.6V), eliminating inductor and main switch losses - critical for high-efficiency PA bias at elevated voltages. |
| 100% duty-cycle dropout operation | Maintains regulation down to VIN – VOUT ≈ 0V by holding main switch fully on - extends usable battery range in portable RF systems. |
| No external Schottky diode required | Internal synchronous N-channel MOSFET replaces lossy diode, increasing efficiency by ~5–8% and simplifying BOM in space-constrained layouts. |
| Low 20µA Burst Mode® quiescent current | Reduces no-load power draw during RF PA standby, directly improving talk time in cellular handsets and wireless modems. |
| Thermal shutdown protection | Disables both power switches if junction temperature exceeds ~150°C - prevents permanent damage during sustained overload or poor PCB thermal design. |
Applications
| WCDMA Transmitter Power Amplifier | Wireless Modem RF Bias Supply |
|---|---|
Use Scenario: Dynamic voltage scaling for 3G UMTS/WCDMA power amplifier during varying transmit power levels. IC Role / Device Role / Timing Role: Synchronous buck regulator with bypass FET, providing programmable VPA from 0.3V to 3.5V synchronized to baseband envelope signal. Use Value: Reduces PA power dissipation by >30% vs fixed-voltage supply, extending battery life and lowering thermal stress in compact handset PCBs. |
Use Scenario: Efficient, low-noise bias supply for LTE/WiMAX modem front-end power amplifiers requiring rapid VOUT slew. IC Role / Device Role / Timing Role: Fast-transient step-down regulator operating in forced continuous mode to track envelope commands with <2µs response. Use Value: Enables 100mA–600mA output current delivery with <10mV ripple using only 4.7µF ceramic COUT, minimizing board area and EMI. |
| Li-ion Powered Portable RF System | Envelope Tracking Power Supply |
Use Scenario: Primary PA supply in battery-operated handheld devices where input voltage sags from 4.2V to 2.7V during discharge. IC Role / Device Role / Timing Role: High-efficiency buck converter supporting 100% duty cycle and low-RDS(ON) bypass FET to maintain regulation across full battery range. Use Value: Delivers stable 1.8V/600mA output down to 2.7V input with >85% efficiency, avoiding premature brownout shutdown. |
Use Scenario: Low-latency, low-IQ power stage in analog envelope tracking architectures feeding GaAs/GaN PAs. IC Role / Device Role / Timing Role: REF-pin-controlled regulator responding to DAC output with minimal phase lag, supporting >1MHz envelope bandwidth. Use Value: Achieves <100ns delay from REF step to SW response, enabling precise PA efficiency optimization without digital controller overhead. |
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 |
|---|---|---|---|
| TPS62231DRVR | Fixed 1.8V output (non-programmable); 3MHz switching; 400mA max; no bypass FET. | Suitable for static-core logic rails, not dynamic PA biasing. | Select only if output voltage is fixed and load current ≤400mA - lacks REF-based programmability and bypass capability of LTC3403EDD#TRPBF. |
| MAX8640YETA+ | 0.6V–3.3V programmable output; 2.25MHz; 600mA; no integrated bypass FET; higher IQ (35µA Burst Mode®). | Supports dynamic scaling but cannot achieve ultra-low-dropout via bypass - less efficient above 3.3V. | Choose when footprint compatibility with 3mm × 3mm TDFN is required and bypass functionality is not needed; verify thermal performance at 600mA in dropout. |
Compared with TPS62231DRVR and MAX8640YETA+, the LTC3403EDD#TRPBF uniquely combines REF-programmable output, integrated bypass FET for >3.6V operation, and 20µA Burst Mode® IQ - making it the only option qualified for WCDMA PA envelope tracking with single-cell Li-ion input.
Availability
LTC3403EDD#TRPBF is available at Aetrix Electronics and suitable for WCDMA transmitter power amplifiers, wireless modem RF bias supplies, and Li-ion powered portable RF systems requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3403EDD#TRPBF 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 precision instrumentation, communications, and industrial markets.
The LTC3403EDD#TRPBF belongs to Linear's high-efficiency DC/DC converter product line, specifically engineered for dynamic RF power amplifier biasing in battery-powered cellular infrastructure and handheld devices - emphasizing low IQ, fast transient response, and integrated bypass functionality.
FAQ
What is the function of the GDR pin on the LTC3403EDD#TRPBF?
The GDR (Gate Driver) pin on the LTC3403EDD#TRPBF drives an optional external P-channel MOSFET to augment current capability or reduce conduction loss beyond the internal switches. It is not required for standard operation - the LTC3403EDD#TRPBF delivers full 600mA using only its internal main, synchronous, and bypass FETs. When used, GDR must be connected to the gate of an external P-FET with appropriate gate resistor to control slew rate and prevent ringing.
How does the LTC3403EDD#TRPBF enter and operate in dropout mode?
The LTC3403EDD#TRPBF enters dropout mode when the programmed VOUT exceeds VIN, causing the internal main P-channel MOSFET to remain continuously on (100% duty cycle). In this state, VOUT = VIN − ILOAD × (RDS(ON) + RL). If VREF > 1.2V, the bypass FET also turns on in parallel, reducing effective RDS(ON) and improving efficiency. Dropout operation is fully supported and characterized down to VIN = 2.5V.
Can the LTC3403EDD#TRPBF be used with ceramic capacitors at both input and output?
Yes, the LTC3403EDD#TRPBF is fully compatible with ceramic input (CIN) and output (COUT) capacitors - its current-mode control loop does not rely on capacitor ESR for stability. Recommended values are ≥10µF X5R/X7R ceramic for CIN and ≥4.7µF for COUT. Avoid Y5V dielectrics due to severe capacitance loss under bias; ensure adequate board-level damping if long input traces exist to prevent ringing-induced VIN spikes.
What is the maximum output voltage achievable with the LTC3403EDD#TRPBF?
The LTC3403EDD#TRPBF supports a maximum regulated output voltage of 3.5V when VREF = 1.167V (since VOUT = 3 × VREF). However, when VREF > 1.2V, the internal bypass P-channel MOSFET activates, connecting VIN directly to VOUT. Thus, the practical maximum VOUT equals VIN (up to 5V), limited only by the absolute maximum rating of the VOUT pin (VIN + 0.3V). This bypass mode is explicitly designed for high-efficiency operation above 3.6V.
How does Burst Mode® operation affect efficiency and output ripple on the LTC3403EDD#TRPBF?
In Burst Mode® operation, the LTC3403EDD#TRPBF reduces quiescent current to 20µA by disabling switching and internal circuitry between bursts, causing output voltage ripple to increase to ~10–20mV peak-to-peak (vs. ~5mV in forced continuous mode). Efficiency at light loads (<10mA) improves significantly - e.g., >80% at 1mA vs. ~55% in continuous mode - but transient response slows due to burst latency. Use MODE = GND to enable Burst Mode®; tie MODE to VIN for low-ripple, fast-response operation.
LTC3403EDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LTC3403EDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3403EDD#TRPBF 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#TRPBF reliable?
The price and inventory of LTC3403EDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3403EDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3403EDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3403EDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3403EDD#TRPBF?
LTC3403EDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3403EDD#TRPBF 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#TRPBF?
For technical support, including LTC3403EDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3403EDD#TRPBF requirements.
6.How does Aetrix verify that LTC3403EDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3403EDD#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3403EDD#TRPBF?
All LTC3403EDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3403EDD#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LTC3403EDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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