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Analog Devices Inc. LTC3440EMS
- Part No.:
- LTC3440EMS
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC3440EMS.pdf
- Description:
- IC REG BUCK BST ADJ 600MA 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,229
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Product details
Overview
LTC3440EMS from Analog Devices (formerly Linear Technology) is a micropower synchronous buck-boost DC/DC converter IC designed for single-cell Li-ion, multi-cell alkaline, or NiMH battery-powered 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 long runtime in palmtop computers and digital cameras.
For engineers reviewing the LTC3440EMS datasheet, LTC3440EMS pinout, LTC3440EMS application, or LTC3440EMS equivalent, key selection considerations include its fixed-frequency or synchronizable 300kHz–2MHz oscillator, programmable soft-start via SHDN/SS, 0.19Ω NMOS and 0.22Ω PMOS internal switches, thermal shutdown protection, and compatibility with compact 10-pin MSOP packaging.
Technical Context
The LTC3440EMS implements a proprietary four-switch buck-boost topology that enables seamless mode transition between buck (VIN > VOUT), buck/boost (VIN ≈ VOUT), and boost (VIN < VOUT) regions without discontinuity or control loop instability. Its voltage-mode PWM architecture uses an error amplifier output (VC pin) to directly control switch duty cycles across all operating modes.
Switching is governed by two independent gate drivers with anti-cross-conduction logic; internal NMOS (SW1/SW2) and PMOS (VIN/VOUT-connected) switches are precisely phased to minimize shoot-through. The MODE/SYNC pin supports either Burst Mode® (25µA IQ) or fixed-frequency operation (600–1000µA IQ), and oscillator frequency is set via external RT resistor or synchronized to an external 2×fSW clock signal.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input/Output Range | 2.5V to 5.5V - supports direct regulation from single Li-ion (2.7–4.2V) or dual alkaline/NiMH without intermediate rails |
| Max Continuous Output Current | 600mA - sufficient for core logic and display power in handheld instruments and MP3 players |
| Peak Efficiency | 96% - achieved using synchronous rectification, eliminating external Schottky diodes for VOUT < 4.3V |
| Quiescent Current (Burst Mode) | 25µA - extends battery life in standby or low-duty-cycle portable applications |
| Switch On Resistance | NMOS: 0.19Ω, PMOS: 0.22Ω - minimizes conduction loss at high load currents |
| Oscillator Frequency Range | 300kHz to 2MHz - adjustable via RT pin; enables optimization of size (higher f) vs. efficiency (lower f) |
| Shutdown Current | <1µA - ensures near-zero battery drain during system sleep or off-state |
| Operating Temperature | –40°C to +85°C - qualified for industrial and consumer portable equipment environments |
Pinout & Package
The LTC3440EMS is housed in a thermally enhanced 10-lead plastic MSOP package (3mm × 3mm footprint, 0.85mm height), with exposed pad not present (unlike DFN variant). Pin 5 (GND) serves as both signal and power ground reference; proper PCB layout requires low-inductance grounding and tight placement of input/output capacitors.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RT (Pin 1) | Oscillator timing input | Connects to ground via resistor to set switching frequency from 300kHz to 2MHz; internal capacitor enables precise f = 6×10¹⁰/RT Hz |
| MODE/SYNC (Pin 2) | Mode control / clock sync input | High = Burst Mode®; low or external 2×fSW clock = fixed-frequency operation; input threshold 0.4–2V |
| SW1 (Pin 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 (Pin 4) | Switch node C/D connection | Connects internal NMOS C and PMOS D; ties to other end of inductor; Schottky to VOUT required if VOUT > 4.3V |
| GND (Pin 5) | Ground reference | Common return for power, signal, and thermal path; must be low-impedance connection to PCB ground plane |
| VOUT (Pin 6) | Regulated output | Delivers regulated voltage; connects to output capacitor (e.g., 22µF ceramic); reverse-current limiting protects during shutdown |
| VIN (Pin 7) | Input supply | Power source input (2.5–5.5V); requires local 4.7µF+ low-ESR ceramic bypass capacitor to GND |
| SHDN/SS (Pin 8) | Shutdown / soft-start control | Ground = shutdown (<1µA IQ); >1.5V = enable; RC network provides controlled VC ramp for inrush-limited startup |
| FB (Pin 9) | Feedback input | Monitors output via resistor divider; internal 1.22V reference enables adjustable VOUT = 1.22×(1+R1/R2) from 2.5V to 5.5V |
| VC (Pin 10) | Error amplifier output | Provides loop compensation node; connects to FB via Type I or Type III network to stabilize all three operating modes |
Key Features
| Feature | Design Value |
|---|---|
| Single-inductor buck-boost topology | Eliminates need for separate buck and boost converters or magnetic coupling; reduces BOM count and board area in space-constrained devices |
| Synchronous rectification (no external diodes) | Enables >96% efficiency at full load and removes forward-voltage drop losses-critical for battery runtime in MP3 players and digital cameras |
| Burst Mode® operation | Reduces quiescent current to 25µA while maintaining regulation, extending usable battery capacity in intermittent-use handheld instruments |
| Programmable and synchronizable oscillator | Allows EMI-sensitive designs (e.g., RF handsets) to avoid interference bands by selecting 300kHz, 1MHz, or 2MHz-or locking to system clock |
| Integrated current limit and thermal shutdown | 2.7A peak switch current limit and 125°C junction temperature cutoff protect against overload and PCB-level thermal runaway |
| Soft-start via SHDN/SS pin | Prevents inrush current and output overshoot during power-up by clamping VC pin until external RC network ramps SHDN/SS above 1.5V |
Applications
| Palmtop Computers | Handheld Instruments |
|---|---|
Use Scenario: Powering 3.3V core logic and LCD interface from a single Li-ion cell (2.7–4.2V). IC Role / Device Role / Timing Role: Primary voltage regulator maintaining stable 3.3V rail across full battery discharge curve. Use Value: Eliminates need for pre-regulator or dual-stage conversion; 96% efficiency preserves battery capacity during active use. | Use Scenario: Supplying 5.0V analog front-end and microcontroller in portable multimeters or data loggers. IC Role / Device Role / Timing Role: Buck-boost regulator delivering regulated output despite varying alkaline battery voltage (1.2–1.6V/cell × 4). Use Value: Enables consistent measurement accuracy and display brightness over entire battery life without manual voltage adjustment. |
| MP3 Players | Digital Cameras |
Use Scenario: Generating 3.3V for audio codec and flash memory from dual NiMH cells (2.4–3.2V). IC Role / Device Role / Timing Role: High-efficiency DC/DC converter supporting burst-mode playback with ultra-low idle current. Use Value: 25µA Burst Mode® IQ extends playback time between charges; compact MSOP fits tight PCB layouts. | Use Scenario: Providing 5.0V for CCD sensor bias and 3.3V for image processor from single Li-ion battery. IC Role / Device Role / Timing Role: Dual-rail capable buck-boost regulator enabling simultaneous high-current sensor activation and low-noise digital processing. Use Value: Seamless VIN-to-VOUT transition avoids brownout during zoom/focus events; thermal shutdown prevents overheating in enclosed housings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS63020DSJR | Higher 95% typical efficiency at 1A; integrated 2A switches; fixed 2.5MHz switching; no Burst Mode® (uses PFM) | Better suited for higher-current applications like portable medical monitors; lacks programmable frequency and explicit Burst Mode® enable control | Select TPS63020DSJR when >600mA output and minimal solution size are prioritized over fine-grained IQ control. |
| MAX77827AEWP+T | Supports wider 1.8–5.5V input; includes I²C programmability and power-good flag; 1.2MHz fixed frequency; 25µA shutdown but no Burst Mode® | Ideal for smart wearables requiring dynamic voltage scaling and telemetry; adds communication overhead not needed in simple fixed-output designs | Choose MAX77827AEWP+T when system-level firmware control and status reporting are required alongside buck-boost regulation. |
Compared with TPS63020DSJR and MAX77827AEWP+T, the LTC3440EMS offers unique user-selectable Burst Mode® activation, precise oscillator programming (300kHz–2MHz), and proven robustness in legacy portable instrumentation-making it optimal for cost-sensitive, battery-life-critical designs where flexibility and simplicity outweigh digital configurability.
Availability
LTC3440EMS is available at Aetrix Electronics and suitable for palmtop computers, handheld instruments, and digital cameras requiring stable component supply across extended production lifecycles and industrial temperature ranges.
Supply support for LTC3440EMS 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 LTC3440EMS belongs to Linear's micropower DC/DC converter product line, engineered specifically for battery-powered portable electronics demanding high efficiency across wide input–output differentials and ultra-low quiescent current.
FAQ
What is the maximum output current capability of the LTC3440EMS?
The LTC3440EMS delivers up to 600mA continuous output current under typical conditions (VIN = 3.6V, VOUT = 3.3V, TA = 25°C). Peak switch current is internally limited to 2.7A to protect the IC. Actual achievable output depends on thermal design, input/output voltage differential, and PCB layout-especially copper area under the MSOP package and inductor placement. Derating is recommended above 85°C ambient.
Does the LTC3440EMS require external Schottky diodes?
No-external Schottky diodes are not required for the LTC3440EMS when VOUT < 4.3V, thanks to its fully synchronous four-switch architecture. However, adding a low-capacitance Schottky (e.g., PMEG2010EA) from SW1 to GND and SW2 to VOUT can improve peak efficiency by 1–2% at light loads. A Schottky from SW2 to VOUT is mandatory if VOUT exceeds 4.3V to clamp SW2 voltage stress.
How is the switching frequency programmed on the LTC3440EMS?
Switching frequency is set by connecting an external resistor (RT) from Pin 1 (RT) to GND. The relationship is fSW = 6×10¹⁰ / RT Hz, yielding 300kHz at 200kΩ and 2MHz at 30kΩ. Alternatively, the MODE/SYNC pin accepts a 2×fSW external clock (pulse width 100ns–2µs) to synchronize operation-useful for EMI reduction in noise-sensitive systems like RF handhelds.
What is the function of the SHDN/SS pin on the LTC3440EMS?
The SHDN/SS pin (Pin 8) combines shutdown and soft-start functionality. Grounding it disables the LTC3440EMS with <1µA quiescent current. Applying >1.5V enables operation; >2.5V ensures full error amplifier range. An RC network from a control signal to this pin creates a controlled voltage ramp, which clamps the VC pin during startup-preventing output overshoot and limiting inrush current into output capacitors.
Can the LTC3440EMS operate with input voltage equal to output voltage?
Yes-the LTC3440EMS is explicitly designed for VIN = VOUT operation, entering its "buck/boost" or "four-switch" region where all four internal MOSFETs are actively phased to maintain regulation without dropout or discontinuity. This behavior is confirmed in the block diagram and operational description: when VIN ≈ VOUT (e.g., 3.6V in → 3.3V out), the device transitions smoothly through the 150ns four-switch conduction window, ensuring stable output with no audible artifacts or regulation loss.
LTC3440EMS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- 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-MSOP
LTC3440EMS FAQ
1.How can I place an order for LTC3440EMS through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3440EMS 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 LTC3440EMS reliable?
The price and inventory of LTC3440EMS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3440EMS is usually 5 days.
3.What payment methods are accepted for LTC3440EMS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3440EMS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3440EMS?
LTC3440EMS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3440EMS 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 LTC3440EMS?
For technical support, including LTC3440EMS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3440EMS requirements.
6.How does Aetrix verify that LTC3440EMS is sourced from the original manufacturer or authorized distributors?
All LTC3440EMS 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 LTC3440EMS meets industry standards.
7.What is the process for return or replacement of LTC3440EMS?
All LTC3440EMS units undergo pre-shipment inspection (PSI). If there is an issue with LTC3440EMS, 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 LTC3440EMS part is unused and in its original packaging.
Return procedure for LTC3440EMS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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