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Analog Devices Inc. LTC3440EDD#PBF
- Part No.:
- LTC3440EDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LTC3440EDD#PBF.pdf
- Description:
- IC REG BUCK BST ADJ 600MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,095
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Product details
Overview
LTC3440EDD#PBF from Analog Devices (formerly Linear Technology) is a micropower synchronous buck-boost DC/DC converter designed for single-cell Li-ion, multi-cell alkaline, or NiMH battery systems where input voltage may fall above, below, or equal to the regulated output. It delivers up to 600mA continuous output current across a 2.5V–5.5V input/output range, achieves 96% peak efficiency via synchronous rectification, and operates with only 25µA quiescent current in Burst Mode®-enabling extended runtime in handheld instruments and MP3 players.
For engineers reviewing the LTC3440EDD#PBF datasheet, LTC3440EDD#PBF pinout, LTC3440EDD#PBF application, or LTC3440EDD#PBF equivalent, key selection considerations include its fixed-frequency programmable oscillator (300kHz–2MHz), user-controllable Burst Mode enable, <1µA shutdown current, integrated 0.19Ω NMOS and 0.22Ω PMOS switches, and compatibility with compact 3mm × 3mm DFN packaging for space-constrained portable designs.
Technical Context
The LTC3440EDD#PBF implements a proprietary four-switch buck-boost topology with continuous transfer function across all operating regions-buck (VIN > VOUT), buck/boost (VIN ≈ VOUT), and boost (VIN < VOUT)-ensuring seamless mode transitions without output discontinuity. Its voltage-mode PWM control loop uses an error amplifier output (VC pin) to directly determine switch duty cycles, with internal phasing logic managing NMOS (B/C) and PMOS (A/D) pairs to maintain regulation.
Switching frequency is set by an external resistor on the RT pin (f = 6×10¹⁰/RT Hz) or synchronized to an external clock applied to MODE/SYNC, supporting noise-sensitive RF applications. The IC integrates soft-start (via SHDN/SS pin clamping), thermal shutdown, reverse-current limiting (–400mA typical), and 2.7A peak current limit protection-enabling robust operation in variable-input battery-powered systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 5.5V - supports full discharge of single Li-ion (2.7V–4.2V) and multi-cell alkaline/NiMH sources without dropout. |
| Output Voltage Range | 2.5V to 5.5V - adjustable via FB resistor divider; reference voltage is 1.22V ±2.3% over temperature. |
| Max Continuous Output Current | 600mA - achievable at VOUT = 3.3V with VIN ≥ 2.7V and proper thermal layout in DFN package. |
| Quiescent Current (Burst Mode) | 25µA typical - minimizes no-load battery drain in always-on portable devices like digital cameras. |
| Shutdown Current | <1µA - enables true system-level power gating during sleep states. |
| Switch RDS(ON) | 0.19Ω (NMOS B/C), 0.22Ω (PMOS A/D) - reduces conduction loss and enables high efficiency at light-to-moderate loads. |
| Oscillator Frequency Range | 300kHz to 2MHz - programmable with RT resistor or synchronizable to external clock for EMI management. |
Pinout & Package
The LTC3440EDD#PBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) that must be soldered to PCB ground for thermal and electrical performance. Pin numbering follows standard top-view DFN convention.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RT (1) | Oscillator timing input | Connects to ground via resistor to set switching frequency (300kHz–2MHz); internal capacitor enables precise f = 6×10¹⁰/RT Hz calculation. |
| MODE/SYNC (2) | Mode control / clock sync input | High = Burst Mode enable; low or external 2×fSW clock = fixed-frequency operation; 100ns–2µs pulse width required for sync. |
| SW1 (3) | Switch node A/B connection | Connects internal NMOS B and PMOS A; ties to one end of inductor; optional Schottky to GND improves light-load efficiency. |
| SW2 (4) | Switch node C/D connection | Connects internal NMOS C and PMOS D; ties to other inductor end; Schottky diode to VOUT required if VOUT > 4.3V. |
| GND (5) | Signal and power ground | Reference for all analog and power circuits; exposed pad (Pin 11) is electrically tied to this pin and must be soldered to PCB ground plane. |
| VOUT (6) | Regulated output supply | Delivers regulated voltage to load; requires ceramic output capacitor (e.g., 22µF) from VOUT to GND for stability and ripple suppression. |
| VIN (7) | Main input supply | Accepts battery or source input (2.5V–5.5V); requires local 4.7µF+ low-ESR ceramic bypass capacitor to GND for IC bias integrity. |
| SHDN/SS (8) | Shutdown and soft-start control | Ground = shutdown (<1µA IQ); >1.5V = enable; RC network here provides controlled VC ramp for inrush-limited startup. |
| FB (9) | Feedback input | Resistor divider tap point; senses output voltage; internal 1.22V reference enables VOUT = 1.22V × (1 + R1/R2) adjustment. |
| VC (10) | Error amplifier output | Provides loop compensation node; connects to FB via Type I or Type III network to stabilize all three operating modes (buck/boost/buck-boost). |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous four-switch topology | Enables continuous regulation across VIN > VOUT, VIN = VOUT, and VIN < VOUT without mode-hopping artifacts or output glitches. |
| Burst Mode® operation | Reduces quiescent current to 25µA while maintaining regulation-critical for battery life in intermittently active devices like handheld test equipment. |
| Integrated low-RDS(ON) MOSFETs | Eliminates need for external Schottky diodes below 4.3V output; reduces BOM count and board area versus discrete buck-boost solutions. |
| Programmable and synchronizable oscillator | Allows EMI-sensitive designs (e.g., RF modules) to shift switching frequency away from critical bands or lock to system clock for spectral cleanup. |
| Thermally enhanced DFN package | 3mm × 3mm footprint with exposed pad achieves θJA = 43°C/W-supports 600mA output in compact portable enclosures without forced air. |
Applications
| Palmtop Computers | Handheld Instruments |
|---|---|
Use Scenario: Powering 3.3V logic and display subsystems from a single Li-ion cell (2.7V–4.2V) during active measurement and data logging. IC Role / Device Role / Timing Role: Primary buck-boost regulator providing stable 3.3V rail independent of battery state-of-charge. Use Value: Eliminates need for separate buck and boost converters; maintains full functionality down to 2.5V input, extending usable battery capacity by ~15% versus fixed-topology alternatives. |
Use Scenario: Supplying 5.0V analog front-end circuitry (ADCs, op-amps) from dual AA alkaline cells (1.8V–3.2V) in portable multimeters and oscilloscopes. IC Role / Device Role / Timing Role: High-efficiency voltage step-up regulator with low-noise fixed-frequency operation to avoid interference with sensitive analog measurements. Use Value: Delivers clean 5V output with <10mVpp ripple at 100mA load using 1MHz switching-reducing post-regulation filtering requirements and PCB area. |
| MP3 Players | Digital Cameras |
Use Scenario: Generating 3.3V for NAND flash memory and audio codec from a single Li-ion cell during playback and file transfer. IC Role / Device Role / Timing Role: Micropower DC/DC converter operating in Burst Mode during idle periods to minimize standby current draw. Use Value: Achieves 25µA quiescent current in Burst Mode-extending weeks-long standby time without compromising fast wake-up response. |
Use Scenario: Powering 3.3V image sensor and 5.0V flash LED driver from a 3.6V Li-ion pack during photo capture sequences with burst current demands. IC Role / Device Role / Timing Role: Dual-rail capable regulator delivering stable 3.3V and 5.0V outputs via separate feedback networks (using external resistors). Use Value: Supports simultaneous high-current flash charging and sensor readout without brownout-enabled by 600mA continuous output and fast transient response. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS63020DSJR | Higher 96% peak efficiency at 1A, but 25µA quiescent current only in Hysteretic Mode-not true Burst Mode; no MODE/SYNC pin for external clock sync. | Preferred for higher-current portable systems (>800mA) where EMI sensitivity is low and fixed-frequency operation is not required. | Select TPS63020DSJR when output current exceeds 600mA and synchronization is unnecessary; verify thermal performance in 2mm × 2mm SON package under continuous load. |
| MAX77827BEWC+T | Supports wider 2.5V–5.5V input and 2.6V–5.2V output ranges; includes I²C interface for dynamic voltage scaling; 22µA quiescent current in ultra-low-power mode. | Targeted at smart wearable platforms requiring programmable output voltage and telemetry-adds complexity versus standalone LTC3440EDD#PBF. | Choose MAX77827BEWC+T when system-level software control of VOUT or real-time efficiency monitoring is needed; avoid if simple fixed-output design suffices. |
Compared with TPS63020DSJR and MAX77827BEWC+T, the LTC3440EDD#PBF offers superior EMI control via programmable/synchronizable oscillator and simpler implementation for fixed-output portable systems, while maintaining best-in-class 25µA Burst Mode quiescent current and proven reliability in commercial handheld instrumentation.
Availability
LTC3440EDD#PBF is available at Aetrix Electronics and suitable for palmtop computers, handheld instruments, and digital cameras requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.
Supply support for LTC3440EDD#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 full product support, datasheet documentation, and application engineering resources for the LTC portfolio.
The LTC3440EDD#PBF belongs to Linear's micropower DC/DC converter family, engineered specifically for battery-powered portable electronics where input voltage varies across the output range and ultra-low quiescent current is essential for runtime extension.
FAQ
What is the minimum input voltage required for the LTC3440EDD#PBF to start switching?
The LTC3440EDD#PBF has a guaranteed input start-up voltage of 2.4V (typical 2.5V). Below this threshold, the internal UVLO circuit prevents switching initiation-even if the output voltage is within regulation range. This ensures reliable cold-start capability from partially discharged Li-ion cells down to 2.5V, making the LTC3440EDD#PBF suitable for deep-discharge portable applications where battery voltage drops below 2.7V during extended use.
Can the LTC3440EDD#PBF regulate output voltage when input equals output (VIN = VOUT)?
Yes-the LTC3440EDD#PBF is explicitly designed for seamless regulation at VIN = VOUT using its four-switch buck-boost topology. In this "buck/boost transition region," the device phases internal NMOS and PMOS switches to maintain continuous conduction and stable output without dropout or mode-hopping artifacts. This behavior is confirmed in the datasheet's typical performance curves and block diagram, distinguishing the LTC3440EDD#PBF from conventional two-switch buck-boost controllers that exhibit discontinuity at VIN = VOUT.
Does the LTC3440EDD#PBF require external Schottky diodes for all applications?
No-external Schottky diodes are only required when VOUT exceeds 4.3V (diode from SW2 to VOUT) or when optimizing for peak efficiency above 50mW (optional diodes from SW1 to GND and SW2 to VOUT). For VOUT ≤ 4.3V, the integrated synchronous MOSFETs eliminate the need for external diodes entirely, reducing BOM cost and PCB area. The LTC3440EDD#PBF datasheet confirms no Schottky diodes are required under these conditions, leveraging its 0.19Ω NMOS and 0.22Ω PMOS switches for full synchronous rectification.
How does Burst Mode® operation affect output voltage ripple on the LTC3440EDD#PBF?
Burst Mode® operation on the LTC3440EDD#PBF introduces variable-frequency ripple whose amplitude and period depend on load current-unlike fixed-frequency mode's predictable 1MHz (or user-set) ripple. At light loads (<10mA), ripple increases due to intermittent energy delivery, but remains within ±1.5% of nominal VOUT for typical 22µF ceramic output capacitors. The LTC3440EDD#PBF's Burst Mode is user-enabled via the MODE/SYNC pin, allowing designers to trade off ripple performance for ultra-low 25µA quiescent current in battery-sensitive applications.
What thermal derating applies to the LTC3440EDD#PBF in its 3mm × 3mm DFN package?
The LTC3440EDD#PBF in the DFN package has a junction-to-ambient thermal resistance (θJA) of 43°C/W under standard JEDEC 2-layer board conditions. At 600mA output and 3.3V VOUT, power dissipation is ~300mW-resulting in ~13°C junction-to-ambient rise above ambient. Derating begins above 85°C ambient; full 600mA output is guaranteed from –40°C to 85°C case temperature. The exposed pad (Pin 11) must be soldered to a minimum 100mm² copper pour for optimal thermal performance, as specified in the LTC3440EDD#PBF datasheet layout guidelines.
LTC3440EDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 600mA
- Frequency - Switching:
- 300kHz ~ 2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LTC3440EDD#PBF FAQ
1.How can I place an order for LTC3440EDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3440EDD#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 LTC3440EDD#PBF reliable?
The price and inventory of LTC3440EDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3440EDD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3440EDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3440EDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3440EDD#PBF?
LTC3440EDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3440EDD#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 LTC3440EDD#PBF?
For technical support, including LTC3440EDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3440EDD#PBF requirements.
6.How does Aetrix verify that LTC3440EDD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3440EDD#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 LTC3440EDD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3440EDD#PBF?
All LTC3440EDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3440EDD#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 LTC3440EDD#PBF part is unused and in its original packaging.
Return procedure for LTC3440EDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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