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Analog Devices Inc. LTC3121IDE#PBF
- Part No.:
- LTC3121IDE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LTC3121IDE#PBF.pdf
- Description:
- IC REG BOOST ADJ 1.5A 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,888
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Product details
Overview
LTC3121IDE#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-up DC/DC converter with true output disconnect, 1.5A current limit, adjustable 100kHz–3MHz switching frequency, and operation down to 500mV input after startup. It delivers up to 12V/400mA from 5V input and supports piezo actuators, PCI Express auxiliary rails, and battery-backed 12V analog supplies.
For engineers reviewing the LTC3121IDE#PBF datasheet, LTC3121IDE#PBF pinout, LTC3121IDE#PBF application, or LTC3121IDE#PBF equivalent, key selection criteria include its 2.2V–15V programmable output, <1µA shutdown current, Burst Mode® operation (25µA IQ), output disconnect capability, and thermally enhanced 12-lead 3mm × 4mm DFN package.
Technical Context
The LTC3121IDE#PBF employs current-mode PWM control with adaptive slope compensation for stable regulation across wide VIN/VOUT ratios. Its dual-MOSFET synchronous rectification uses an N-channel switch (0.121Ω RDS(ON)) and P-channel rectifier (0.188Ω RDS(ON)), enabling up to 95% efficiency at full load.
It integrates a 10ms closed-loop soft-start, zero-current detection for light-load efficiency, anti-ringing control above VIN+2V, and overvoltage lockout at ~16.2V. The VCC regulator derives bias from VIN or VOUT, supporting operation when VIN drops below 3V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 1.8V to 5.5V start-up; sustains regulation down to 0.5V after VOUT ≥ 2.2V - enables deep discharge of single-cell Li-ion or backup capacitors |
| VOUT Range | 2.2V to 15V programmable via FB resistor divider - supports 3.3V, 5V, 7.5V, 12V, and 15V system rails |
| Switching Frequency | 100kHz to 3MHz adjustable via RT resistor - allows optimization for size (high-freq) or EMI (low-freq) |
| Peak Switch Current Limit | 1.5A minimum (1.8A typical) - sets maximum inductor peak current and short-circuit current capability |
| Quiescent Current | 25µA in Burst Mode®, <1µA in shutdown - extends battery life in always-on sensor nodes |
| Efficiency | Up to 95% at full load - achieved via synchronous rectification and low RDS(ON) MOSFETs |
| Output Disconnect | True disconnect in shutdown - eliminates body-diode leakage and allows VOUT to fully discharge |
Pinout & Package
The LTC3121IDE#PBF is housed in a thermally enhanced 12-lead (3mm × 4mm × 0.75mm) plastic DFN package with exposed PGND pad (Pin 13) requiring soldering to PCB ground plane for rated thermal performance (θJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (1) | Power switch node | Connects to inductor; internal N-MOSFET drain - high dv/dt node requiring short, wide trace |
| PGND (2, 13) | Power ground return | Primary return path for inductor current and output capacitor - must be tied directly to PCB ground plane |
| VIN (3) | Main input supply | Accepts 1.8V–5.5V; powers IC before VOUT rises - requires ≥4.7µF ceramic bypass to PGND |
| PWM/SYNC (4) | Mode control & sync input | High = fixed-frequency PWM; Low = Burst Mode®; external clock = synchronization - not floating |
| VCC (5) | Internal LDO output | Regulated ~4.25V rail powering gate drivers - requires ≥4.7µF capacitor to SGND |
| RT (6) | Oscillator programming | Resistor to SGND sets fSW per fOSC(MHz) = 57.6 / RT(kΩ) - enables precise frequency tuning |
| VC (7) | Error amplifier output | Loop compensation node - connects RC network for stability across operating conditions |
| FB (8) | Feedback input | Senses resistor divider ratio; 1.202V reference sets VOUT = 1.202V × (1 + R1/R2) |
| SD (9) | Shutdown control | Logic-level enable: >1.6V = on, <0.25V = shutdown with <1µA IQ - supports system power sequencing |
| SGND (10) | Signal ground reference | Analog ground for FB, VC, and CAP - separate from PGND but connected at single point |
| VOUT (11) | Regulated output & rectifier source | Drives synchronous P-MOSFET source; disconnected from VIN during shutdown |
| CAP (12) | Synchronous rectifier gate drive reference | Capacitor to VOUT creates ~5.6V below VOUT - enables proper P-MOSFET gate biasing |
Key Features
| Feature | Design Value |
|---|---|
| True output disconnect | Eliminates reverse current and enables full VOUT discharge during shutdown - critical for safety-critical or multi-rail systems |
| Adjustable 100kHz–3MHz switching | Enables compact designs using <10µH inductors while avoiding AM radio band - reduces solution footprint by >40% vs 500kHz parts |
| Burst Mode® operation | Reduces no-load IQ to 25µA - extends runtime in battery-powered IoT sensors with intermittent wake cycles |
| Inrush current limiting | 10ms closed-loop soft-start prevents input surge during power-up - protects weak sources like coin cells or supercaps |
| Robust protection suite | Includes overvoltage lockout (~16.2V), thermal shutdown (170°C), and short-circuit current foldback - ensures reliability in unattended deployments |
Applications
| Piezo Actuator Drive | PCI Express Auxiliary Power |
|---|---|
Use Scenario: Driving high-voltage piezoelectric transducers in ultrasonic cleaners or precision positioning stages. IC Role / Device Role / Timing Role: Step-up converter generating 12V–15V from 3.3V or 5V logic rails with fast transient response. Use Value: Output disconnect prevents unintended actuator movement during standby; Burst Mode® minimizes idle power in duty-cycled systems. |
Use Scenario: Providing regulated 12V auxiliary power to PCIe add-in cards from motherboard 3.3V or 5V rails. IC Role / Device Role / Timing Role: Synchronous boost regulator delivering up to 400mA with tight voltage regulation under dynamic load steps. Use Value: True output disconnect isolates card power during hot-plug events; 95% efficiency reduces thermal load in dense slot configurations. |
| Small DC Motor Supply | 12V Analog Rail from Battery |
Use Scenario: Powering miniature 12V DC motors in portable medical devices or robotics from single-cell Li-ion (2.7–4.2V). IC Role / Device Role / Timing Role: High-efficiency boost converter sustaining motor torque down to 0.5V input during deep discharge. Use Value: 500mV minimum operating voltage maximizes usable battery capacity; soft-start prevents motor jerk at startup. |
Use Scenario: Generating clean 12V analog supply for op-amps, ADCs, or DACs from aging alkaline or LiFePO₄ batteries. IC Role / Device Role / Timing Role: Low-noise, low-ripple boost regulator with selectable PWM/Burst Mode® for mixed-signal systems. Use Value: Synchronizable oscillator avoids noise coupling into sensitive analog sections; CAP pin filtering suppresses gate-drive noise on VOUT. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61088RHLR | Higher 4.5A current limit; fixed 500kHz/2MHz switching; no output disconnect; 2.7V–12V VIN | Lacks true output disconnect and sub-1V operation - unsuitable for deep-discharge battery systems | Choose for higher current (>1.5A) needs where disconnect is unnecessary and input stays >2.7V |
| MAX77818EWL+ | Integrated battery charger + boost; 2A switch; 2.5V–5.5V VIN; no sub-1V operation; different package (20-pin WLP) | Combines charging and boosting - adds complexity if only boost function is required | Choose only when battery charging and regulated boost are both needed in space-constrained wearables |
Compared with TPS61088RHLR and MAX77818EWL+, the LTC3121IDE#PBF uniquely supports 0.5V operation and true output disconnect - making it the only viable option for ultra-low-VIN energy harvesting or fail-safe shutdown requirements.
Availability
LTC3121IDE#PBF is available at Aetrix Electronics and suitable for piezo actuator drive, PCIe auxiliary power, and 12V analog rail generation requiring stable component supply, long-term industrial availability, and guaranteed -40°C to 125°C operation.
Supply support for LTC3121IDE#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 its high-performance analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LTC3121IDE#PBF belongs to Linear's precision DC/DC converter family, designed specifically for demanding applications requiring ultra-low input voltage operation, output disconnect, and high efficiency across wide load ranges.
FAQ
What is the minimum input voltage required for the LTC3121IDE#PBF to start up and regulate?
The LTC3121IDE#PBF requires a minimum of 1.7V (typical 1.8V) to initiate startup and begin regulating the output. Once regulation is established and VOUT reaches ≥2.2V, the device continues operation with input voltages as low as 0.5V - a key feature for maximizing energy extraction from depleted batteries or backup capacitors. This behavior is confirmed in the Electrical Characteristics table under "Minimum Start-Up Voltage" and "Input Voltage Range After VOUT ≥ 2.2V".
Does the LTC3121IDE#PBF support true output disconnect, and how does it work?
Yes, the LTC3121IDE#PBF provides true output disconnect during shutdown: when the SD pin is pulled low (<0.25V), both internal MOSFETs are turned off, physically isolating VOUT from VIN and allowing VOUT to fully discharge through the load. This eliminates body-diode conduction and reverse current - critical for safety, sequencing, and preventing unintended peripheral activation. The feature is explicitly documented in the Features section and Pin Functions description for the VOUT pin.
How is the switching frequency programmed on the LTC3121IDE#PBF?
The LTC3121IDE#PBF switching frequency is set by an external resistor (RT) connected from Pin 6 (RT) to SGND, using the formula fOSC(MHz) = 57.6 / RT(kΩ). For example, a 57.6kΩ resistor yields 1MHz operation. The device also supports synchronization to an external clock applied to the PWM/SYNC pin, with RT adjusted to ~25% below the sync frequency. This programmability is detailed in the Pin Functions and Operation sections of the datasheet.
What protection features are integrated into the LTC3121IDE#PBF?
The LTC3121IDE#PBF integrates overvoltage lockout (~16.2V), thermal shutdown (170°C typical), short-circuit current foldback (reduced to 1A under overload), and input UVLO (VCC <1.6V). It also features robust MOSFET gate drive design and anti-ringing control to suppress EMI. All protections are active during normal operation and fault conditions, as verified in the Absolute Maximum Ratings, Electrical Characteristics, and Operation sections.
Can the LTC3121IDE#PBF operate with input voltages higher than the programmed output voltage?
Yes, the LTC3121IDE#PBF maintains regulation even when VIN exceeds VOUT (buck-mode operation), though efficiency and output current capability decrease significantly. This behavior is explicitly noted in the Applications Information section under "VIN > VOUT Operation", and confirmed in Typical Performance Characteristics curves showing efficiency vs. load at varying VIN/VOUT combinations.
LTC3121IDE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.8V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 2.2V
- Voltage - Output (Max):
- 15V
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- Up to 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-DFN (4x3)
LTC3121IDE#PBF FAQ
1.How can I place an order for LTC3121IDE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3121IDE#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 LTC3121IDE#PBF reliable?
The price and inventory of LTC3121IDE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3121IDE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3121IDE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3121IDE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3121IDE#PBF?
LTC3121IDE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3121IDE#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 LTC3121IDE#PBF?
For technical support, including LTC3121IDE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3121IDE#PBF requirements.
6.How does Aetrix verify that LTC3121IDE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3121IDE#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 LTC3121IDE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3121IDE#PBF?
All LTC3121IDE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3121IDE#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 LTC3121IDE#PBF part is unused and in its original packaging.
Return procedure for LTC3121IDE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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