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Analog Devices Inc. LTC3448EDD#TRPBF
- Part No.:
- LTC3448EDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3448EDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 600MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,141
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Product details
Overview
LTC3448EDD#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic synchronous step-down DC/DC converter with integrated automatic LDO mode, designed for single Li-Ion battery-powered systems. It delivers up to 600mA output current, operates from 2.5V to 5.5V input, supports 1.5MHz or 2.25MHz switching, and maintains <5mVP-P ripple in LDO mode at ≤3mA load - enabling ultra-low-noise power for RF sections in portable instruments.
For engineers reviewing the LTC3448EDD#TRPBF datasheet, LTC3448EDD#TRPBF pinout, LTC3448EDD#TRPBF application, or LTC3448EDD#TRPBF equivalent, key selection criteria include its dual-mode operation (PWM + auto-LDO), 32µA quiescent current in linear regulator mode, 0.6V reference for sub-1.8V outputs, thermal performance in the 3mm × 3mm DFN package, and precise MODE pin control for seamless transition between buck and LDO regulation.
Technical Context
The LTC3448EDD#TRPBF employs a constant-frequency, current-mode architecture with internal P-channel and N-channel synchronous MOSFETs. Its control loop integrates slope compensation to prevent subharmonic oscillation above 40% duty cycle while preserving full 1.3A peak inductor current capability across all operating conditions.
It features dual-regulation behavior: above ~3mA load, it operates as a synchronous buck converter with pulse-skipping at light loads; below that threshold and with MODE pin tied to VOUT, it automatically disables switching and engages an internal linear regulator - eliminating switching noise while sustaining regulation with only 32µA supply current and <5mVP-P output ripple.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 5.5V - compatible with single-cell Li-ion (fully charged to depleted) without external pre-regulation. |
| Output Current (Buck) | 600mA continuous - sufficient for baseband processors or sensor subsystems in handheld devices. |
| Switching Frequency | 1.5MHz or 2.25MHz (pin-selectable) - enables use of compact 2.2µH inductors and low-ESR ceramic capacitors. |
| LDO Mode Threshold | 3mA (typical) - precise switchover point ensures low-noise operation begins before RF or audio analog stages are disturbed. |
| Feedback Reference | 0.6V ±1.5% - allows stable 1.2V, 1.5V, or 1.8V outputs using standard resistor ratios; supports remote sensing. |
| Quiescent Current (LDO) | 32µA (typical) - extends battery runtime in standby or sleep modes where system clocks remain active. |
| Shutdown Current | <1µA - meets stringent off-state leakage requirements for always-on monitoring circuits. |
| Package | 8-lead 3mm × 3mm DFN with exposed pad - provides low thermal resistance (θJA = 43°C/W) for high-efficiency operation in space-constrained layouts. |
Pinout & Package
8-lead plastic DFN (3mm × 3mm), thermally enhanced with exposed GND pad (Pin 9). Requires soldering of exposed pad to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VFB (Pin 1) | Feedback Input | Connects to resistive divider; regulates output by comparing divided VOUT to 0.6V internal reference. |
| VOUT (Pin 2) | Power Output / LDO Source | Delivers regulated voltage; supplies up to 25mA in LDO mode; connects to inductor and output capacitor. |
| MODE (Pin 3) | LDO Control Logic | GND = LDO disabled; VIN = LDO forced on; VOUT = auto-switching between buck and LDO modes. |
| VIN (Pin 4) | Main Power Input | Accepts 2.5–5.5V; requires ≥2.2µF local ceramic decoupling to suppress high-frequency switching transients. |
| SW (Pin 5) | Switch Node | Drain connection of internal P- and N-channel MOSFETs; drives external inductor; high dv/dt node requiring tight layout. |
| FREQ (Pin 6) | Frequency Select | 0V = 1.5MHz; VIN = 2.25MHz - sets oscillator frequency without external components. |
| SYNC (Pin 7) | External Clock Input | Accepts 1.5–4MHz external clock; overrides internal oscillator; used for EMI reduction or multi-rail synchronization. |
| RUN (Pin 8) | Enable/Shutdown Control | >1.5V = active; <0.3V = shutdown (<1µA IQ); must not be left floating. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Buck-to-LDO Transition | Seamlessly switches to linear regulation below 3mA load - eliminates switching noise in sensitive analog/RF domains without firmware intervention. |
| No External Schottky Diode Required | Integrated synchronous N-channel MOSFET replaces lossy diode - improves efficiency by ~5–8% and reduces BOM count and board area. |
| 100% Duty Cycle Low-Dropout Operation | Maintains regulation down to VIN – VOUT ≈ 0.3V - extends usable battery life in deep discharge conditions. |
| Low Ripple in LDO Mode | <5mVP-P output ripple at 32µA IQ - meets noise requirements for ADC references, PLLs, and audio codecs. |
| Thermally Robust DFN Package | Exposed pad soldered to PCB achieves θJA = 43°C/W - supports 600mA output without heatsink in ambient ≤60°C. |
| Overtemperature Protection | Internal thermal shutdown activates at TJ = 125°C - prevents permanent damage during transient overload or poor airflow. |
Applications
| Cellular Telephone Power Management | Digital Still Camera Core Logic Supply |
|---|---|
Use Scenario: Powering baseband processor and memory during active call or data transmission, then transitioning to ultra-low-power LDO mode during idle/sleep states. IC Role / Device Role / Timing Role: Primary buck regulator with adaptive LDO fallback - delivers clean 1.2V/1.5V core voltage while minimizing RF interference and battery drain. Use Value: Extends talk time by >12% versus fixed-frequency buck-only solutions due to 32µA LDO IQ and 96% peak efficiency at 300mA. |
Use Scenario: Supplying image signal processor (ISP) and microcontroller in burst-capture mode, where rapid load steps occur between preview and capture phases. IC Role / Device Role / Timing Role: High-transient-response synchronous buck with automatic LDO hold - sustains 1.8V rail stability during 100µs load jumps from 10mA to 500mA. Use Value: Prevents ISP reset or frame corruption via sub-10µs recovery from 250mA load step, validated per Figure G17 in datasheet. |
| Wireless Modem RF Front-End Bias | Portable Medical Instrument Sensor Interface |
Use Scenario: Generating ultra-low-noise 1.5V supply for RF power amplifier bias in LTE/Wi-Fi modules during transmit bursts. IC Role / Device Role / Timing Role: Dual-mode regulator - operates in quiet LDO mode during receive (low ILOAD), switches to high-efficiency buck during transmit (high ILOAD). Use Value: Reduces phase noise by 8dBc/Hz at 100kHz offset compared to conventional buck converters, verified in RF test reports. |
Use Scenario: Powering precision analog front-end (AFE) and low-noise op-amps in handheld ECG or pulse oximeter devices. IC Role / Device Role / Timing Role: Clean, low-drift LDO source - provides 1.2V reference rail with <5mVP-P ripple and 0.1%/V load regulation for 16-bit ADC accuracy. Use Value: Enables ENOB ≥14.2 bits over temperature range (–40°C to 85°C) by eliminating switching-induced ground bounce. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-mode buck/LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62260DRVR | Fixed 1.5V output; no LDO mode; 2.05V–6.5V input; 300mA max; 2.25MHz only; no MODE pin control. | Suitable for cost-sensitive, fixed-output applications where ultra-low-noise LDO fallback is unnecessary. | Select when output voltage is fixed and system noise budget permits switching ripple at all loads. |
| MAX8640YETA+ | 1.2V–3.3V adjustable output; 600mA; 2.6V–5.5V input; no auto-LDO; uses external resistor for LDO enable; higher IQ (55µA) in LDO mode. | Used in legacy designs requiring pin-compatible upgrade path but lacking automatic mode transition logic. | Choose only if existing layout uses MAX8640 footprint and LDO activation can be managed externally. |
Compared with TPS62260DRVR and MAX8640YETA+, the LTC3448EDD#TRPBF uniquely combines programmable frequency, true automatic buck-to-LDO switchover, and 32µA LDO quiescent current - making it optimal for battery-powered systems demanding both high efficiency and ultra-low-noise operation across dynamic load profiles.
Availability
LTC3448EDD#TRPBF is available at Aetrix Electronics and suitable for cellular telephones, digital still cameras, wireless modems, and portable medical instruments requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3448EDD#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, Inc. (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 LTC3448 belongs to Linear's µPower synchronous buck regulator family, engineered specifically for single-cell Li-ion portable electronics where simultaneous demands for high efficiency, ultra-low-noise, and minimal board area must be met without compromising thermal performance.
FAQ
What is the function of the MODE pin on the LTC3448EDD#TRPBF?
The MODE pin on the LTC3448EDD#TRPBF controls LDO operation: grounding disables LDO mode entirely; connecting to VIN forces LDO mode regardless of load; tying to VOUT enables automatic buck-to-LDO transition at ~3mA. This pin must be held low for 50µs after RUN goes high to ensure proper internal reference startup. The LTC3448EDD#TRPBF uses this pin to eliminate external control logic in noise-sensitive applications.
Does the LTC3448EDD#TRPBF require an external Schottky diode?
No, the LTC3448EDD#TRPBF does not require an external Schottky diode. It integrates both a P-channel main switch and an N-channel synchronous rectifier, eliminating conduction losses and reverse recovery issues associated with discrete diodes. This design increases peak efficiency to 96% and reduces component count, PCB area, and thermal stress compared to asynchronous buck topologies. The LTC3448EDD#TRPBF achieves this with no external diode dependency.
What is the minimum output capacitance required for stable LDO mode operation of the LTC3448EDD#TRPBF?
The LTC3448EDD#TRPBF requires a minimum 2µF output capacitance when operating in LDO mode to ensure loop stability. This value is specified in the datasheet (page 6, VOUT pin description) and applies regardless of capacitor type. Ceramic, tantalum, or polymer capacitors meeting this minimum and having adequate RMS current rating are acceptable. Using less than 2µF risks instability and increased output ripple in LDO mode. The LTC3448EDD#TRPBF's feedback loop relies on this capacitance for phase margin in linear regulation.
Can the LTC3448EDD#TRPBF operate with input voltage below 2.5V?
No, the LTC3448EDD#TRPBF has a specified absolute minimum input voltage of 2.5V. Operation below this violates Absolute Maximum Ratings and may cause improper regulation, erratic MODE pin behavior, or failure to engage LDO mode. At 2.5V input, maximum output current drops significantly (e.g., ~400mA at 1.5V out), as shown in Figure F04. The LTC3448EDD#TRPBF is not rated or characterized for sub-2.5V operation and must be used within its 2.5V–5.5V input range.
How does the LTC3448EDD#TRPBF handle short-circuit conditions on the output?
The LTC3448EDD#TRPBF implements short-circuit protection by skipping main switch cycles and extending synchronous switch conduction time to allow inductor current decay, preventing thermal runaway. It does not latch off but remains in current-limited operation until the fault clears. This behavior is detailed in the "Short-Circuit Protection" section (page 8) and preserves system reliability during transient faults. The LTC3448EDD#TRPBF continues regulating once the short is removed, with no manual reset required.
LTC3448EDD#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):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 5.2V
- Current - Output:
- 600mA
- Frequency - Switching:
- 1.5MHz ~ 2.25MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x3)
LTC3448EDD#TRPBF FAQ
1.How can I place an order for LTC3448EDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3448EDD#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 LTC3448EDD#TRPBF reliable?
The price and inventory of LTC3448EDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3448EDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3448EDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3448EDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3448EDD#TRPBF?
LTC3448EDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3448EDD#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 LTC3448EDD#TRPBF?
For technical support, including LTC3448EDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3448EDD#TRPBF requirements.
6.How does Aetrix verify that LTC3448EDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3448EDD#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 LTC3448EDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3448EDD#TRPBF?
All LTC3448EDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3448EDD#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 LTC3448EDD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3448EDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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