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Analog Devices Inc. LTC3121EDE#PBF
- Part No.:
- LTC3121EDE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LTC3121EDE#PBF.pdf
- Description:
- IC REG BOOST ADJ 1.5A 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,125
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Product details
Overview
LTC3121EDE#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-up DC/DC converter with true output disconnect, 1.5A current limit, and programmable output voltage up to 15V. It operates from input voltages as low as 1.8V at startup and sustains regulation down to 500mV after startup, enabling extended runtime in battery-powered piezo actuators and backup-capacitor systems.
For engineers reviewing the LTC3121EDE#PBF datasheet, LTC3121EDE#PBF pinout, LTC3121EDE#PBF application, or LTC3121EDE#PBF equivalent, key selection considerations include its 100kHz–3MHz adjustable switching frequency, 25µA Burst Mode quiescent current, output disconnect capability, thermal shutdown protection, and compatibility with low-ESR ceramic output capacitors in space-constrained designs.
Technical Context
The LTC3121EDE#PBF implements fixed-frequency current-mode PWM control with adaptive slope compensation for stable operation across wide duty cycles. Its dual-MOSFET synchronous rectification-using an N-channel main switch (0.121Ω RDS(ON)) and P-channel synchronous rectifier (0.188Ω RDS(ON))-enables up to 95% efficiency at full load while supporting discontinuous conduction mode via zero-current detection.
It integrates a 10ms closed-loop soft-start, overvoltage lockout (16.2V), thermal shutdown (170°C), and anti-ringing control activated when VOUT ≥ VIN + 2V. The internal VCC LDO regulates to ~4.25V from VIN or VOUT, powering gate drivers and control circuitry without external bias rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 1.8V to 5.5V startup; sustains regulation from 500mV after VOUT ≥ 2.2V - enables deep discharge of single-cell Li-ion or supercapacitors. |
| Output Voltage Range | 2.2V to 15V, set by external resistor divider - supports 5V, 7.5V, 12V, and 15V analog rails from low-voltage sources. |
| Switching Frequency | 100kHz to 3MHz, adjustable via RT pin - allows optimization for size (high-freq) or EMI (low-freq) without changing inductor value. |
| Peak Switch Current Limit | 1.5A minimum (1.8A typical) - defines maximum deliverable output current under worst-case conditions (e.g., low VIN, high VOUT). |
| Burst Mode Quiescent Current | 25µA on VIN - reduces standby power in always-on sensor nodes or energy-harvesting systems. |
| Shutdown Current | <1µA - ensures negligible battery drain during system sleep or fault recovery. |
| Efficiency | Up to 95% at full load - achieved via synchronous rectification and low RDS(ON) MOSFETs, minimizing conduction losses. |
Pinout & Package
The LTC3121EDE#PBF is housed in a thermally enhanced 12-lead (4mm × 3mm × 0.75mm) 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; carries high di/dt current - requires short, wide trace to minimize EMI and voltage overshoot. |
| PGND (2, 13) | Power ground reference | Primary return path for inductor and output capacitor currents - must be tied directly to PCB ground plane. |
| VIN (3) | Main input supply | Primary power source; powers internal circuitry unless VOUT > VIN and VIN < 3V - requires ≥4.7µF low-ESR ceramic bypass. |
| PWM/SYNC (4) | Mode control & clock sync | Selects Burst Mode (low), fixed-frequency PWM (high), or external clock sync - not floating; drives internal oscillator. |
| VCC (5) | Internal LDO output | ~4.25V regulated rail for gate drivers and logic - requires ≥4.7µF capacitor to SGND; UVLO at 1.6V disables switching. |
| RT (6) | Oscillator frequency programming | Resistor to SGND sets fOSC = 57.6/RT (MHz); enables precise frequency tuning or sync offset calibration. |
| VC (7) | Error amplifier output | Loop compensation node - connects RC network to SGND for stability across operating conditions. |
| FB (8) | Feedback input | Senses resistive divider ratio; 1.202V reference sets VOUT = 1.202V × (1 + R1/R2) - defines output regulation accuracy. |
| SD (9) | Logic-controlled shutdown | Active-high enable (≥1.6V); active-low shutdown (<0.25V) - disconnects VOUT from VIN and reduces IQ to <1µA. |
| SGND (10) | Signal ground reference | Reference for FB, VC, and CAP - must be routed separately from PGND to avoid noise coupling into feedback path. |
| VOUT (11) | Regulated output & rectifier source | Delivers boosted voltage; internal P-MOSFET source - disconnects from VIN during shutdown to prevent backfeed. |
| CAP (12) | Synchronous rectifier gate drive reference | Provides elevated ground (~5.6V below VOUT) for P-MOSFET gate drive - requires 100nF low-ESR capacitor to VOUT. |
Key Features
| Feature | Design Value |
|---|---|
| True output disconnect | VOUT fully discharges to 0V in shutdown with no reverse current - eliminates need for external blocking diodes in backup power paths. |
| Inrush current limiting | 10ms closed-loop soft-start limits peak input surge - prevents brownout in weak input sources like thin-film batteries or small supercapacitors. |
| Adjustable switching frequency | 100kHz–3MHz range via RT resistor - enables compact designs using ≤6.8µH inductors while maintaining efficiency above 90%. |
| Burst Mode operation | 25µA quiescent current with 1%–2% VOUT ripple - extends battery life in intermittent-load applications such as wireless sensor wake-ups. |
| Robust protection suite | Thermal shutdown (170°C), output overvoltage lockout (16.2V), short-circuit current foldback (1A limit), and anti-ringing control - ensures reliable operation under fault conditions. |
Applications
| Piezo Actuator Drive | PCI Express Auxiliary Rail |
|---|---|
Use Scenario: Driving high-voltage piezoelectric elements requiring 12V–15V from a 3.3V or 5V system rail. IC Role / Device Role / Timing Role: Synchronous boost converter providing regulated high-voltage output with fast transient response and minimal output droop. Use Value: Enables precise actuator positioning without external charge pumps or transformers, leveraging 95% efficiency and output disconnect to eliminate holdover voltage. |
Use Scenario: Generating stable 12V auxiliary power for PCIe add-in cards from a 3.3V or 5V motherboard supply. IC Role / Device Role / Timing Role: Step-up regulator delivering up to 400mA at 12V with tight line/load regulation and low-noise PWM operation. Use Value: Meets PCIe specification requirements for auxiliary power sequencing and isolation, with SD pin enabling synchronized power-down during card hot-plug events. |
| Small DC Motor Supply | 12V Analog Rail from Battery |
Use Scenario: Powering miniature brushed DC motors (e.g., in portable medical devices) requiring 7.5V–12V from a single 3.7V Li-ion cell. IC Role / Device Role / Timing Role: High-efficiency boost converter with inrush limiting and thermal protection to handle motor stall currents. Use Value: Delivers consistent torque across battery discharge curve (down to 3.0V), with Burst Mode extending operational time between charges. |
Use Scenario: Creating a clean 12V analog supply for op-amps, ADCs, or DACs from a 3.6V lithium coin cell or backup capacitor. IC Role / Device Role / Timing Role: Low-quiescent-current boost regulator with output disconnect to isolate analog circuitry during system sleep. Use Value: Maintains 12V rail stability during microamp-level standby, with <1µA shutdown current preventing capacitor self-discharge in long-term backup applications. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61236RGER | Fixed 5V output; no adjustable VOUT; 2A switch current limit; 2.5MHz max fSW | Not suitable for variable-output or >5V applications; lacks output disconnect and true 500mV operation | Choose only for cost-sensitive 5V-only designs where programmability and ultra-low-VIN operation are unnecessary. |
| MAX17222ETA+ | Lower 0.5A current limit; 1.8V–5.5V input; 2.5V–5.25V output; 300nA shutdown IQ | Targeted at ultra-low-power sub-100mA loads; insufficient for 400mA 12V applications | Select when quiescent current is paramount and output current demand is ≤100mA - not a functional replacement for LTC3121EDE#PBF's 1.5A capability. |
Compared with TPS61236RGER and MAX17222ETA+, the LTC3121EDE#PBF uniquely combines 15V programmable output, true output disconnect, 500mV post-startup operation, and 1.5A current capability - making it irreplaceable in high-voltage, high-current, battery-deep-discharge applications where both flexibility and robustness are required.
Availability
LTC3121EDE#PBF is available at Aetrix Electronics and suitable for piezo actuator drive, PCI Express auxiliary rail generation, and 12V analog rail from battery applications requiring stable component supply, long-lifecycle support, and guaranteed lead-free compliance.
Supply support for LTC3121EDE#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 legacy of high-performance power management ICs with rigorous reliability testing and automotive-grade qualification pathways.
The LTC3121EDE#PBF belongs to Linear's precision synchronous boost converter product line, designed specifically for demanding applications requiring wide input range, output disconnect, and high efficiency across light-to-full load conditions.
FAQ
What is the minimum input voltage required for the LTC3121EDE#PBF to start up and regulate?
The LTC3121EDE#PBF requires a minimum input voltage of 1.8V to initiate startup and begin regulating the output. Once regulation is established and VOUT reaches ≥2.2V, the device continues operation even as VIN drops to 500mV - a critical feature for maximizing energy extraction from deeply discharged 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 LTC3121EDE#PBF support external synchronization of its switching frequency?
Yes, the LTC3121EDE#PBF supports external clock synchronization via the PWM/SYNC pin. When an external clock signal (0.1MHz–3MHz) is applied, the internal oscillator locks to it, disabling Burst Mode. An external RT resistor must be set to ~25% below the sync frequency (RT = 73.2/fSYNC) to ensure stable locking. This capability is documented in the Pin Functions section and Typical Performance Characteristics (Figure G23–G24).
How does the output disconnect feature of the LTC3121EDE#PBF function during shutdown?
During shutdown (SD pin < 0.25V), the LTC3121EDE#PBF disables both internal MOSFETs and actively isolates VOUT from VIN, preventing body-diode conduction. This allows VOUT to fully discharge to 0V and draws <1µA from the input source. The feature is implemented via dedicated control logic that decouples the P-channel synchronous rectifier gate drive - verified in the Block Diagram and Applications Information sections.
What is the purpose of the CAP pin on the LTC3121EDE#PBF, and what capacitor value is recommended?
The CAP pin on the LTC3121EDE#PBF serves as the low-side reference for the P-channel synchronous rectifier gate driver, generating an elevated ground rail ~5.6V below VOUT. A 100nF low-ESR ceramic capacitor must be placed between CAP and VOUT to stabilize this rail and ensure proper gate turn-on. This requirement is specified in the Pin Functions section and Figure 1 of the datasheet.
Can the LTC3121EDE#PBF operate with an input voltage higher than its output voltage?
Yes, the LTC3121EDE#PBF can operate in VIN > VOUT mode (buck-like behavior), maintaining regulation but with reduced efficiency and lower output current capability. This is explicitly stated in the "VIN > VOUT Operation" subsection of the Operation chapter and reflected in the Typical Performance Characteristics curves showing efficiency degradation at high VIN/VOUT ratios.
LTC3121EDE#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)
LTC3121EDE#PBF FAQ
1.How can I place an order for LTC3121EDE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3121EDE#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 LTC3121EDE#PBF reliable?
The price and inventory of LTC3121EDE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3121EDE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3121EDE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3121EDE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3121EDE#PBF?
LTC3121EDE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3121EDE#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 LTC3121EDE#PBF?
For technical support, including LTC3121EDE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3121EDE#PBF requirements.
6.How does Aetrix verify that LTC3121EDE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3121EDE#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 LTC3121EDE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3121EDE#PBF?
All LTC3121EDE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3121EDE#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 LTC3121EDE#PBF part is unused and in its original packaging.
Return procedure for LTC3121EDE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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