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Analog Devices Inc. LTC3121IDE#TRPBF
- Part No.:
- LTC3121IDE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LTC3121IDE#TRPBF.pdf
- Description:
- IC REG BOOST ADJ 1.5A 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:889
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Product details
Overview
LTC3121IDE#TRPBF 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 (start-up) and down to 500mV (post-start), enabling extended battery runtime in low-voltage systems such as piezo actuators and backup-capacitor-powered rails.
For engineers reviewing the LTC3121IDE#TRPBF datasheet, LTC3121IDE#TRPBF pinout, LTC3121IDE#TRPBF application, or LTC3121IDE#TRPBF equivalent, key selection considerations include its 25µA Burst Mode quiescent current, 100kHz–3MHz adjustable switching frequency, output disconnect capability, 12-lead 3mm × 4mm DFN package, and robust protection against short-circuit, overvoltage, and thermal overload.
Technical Context
The LTC3121IDE#TRPBF implements fixed-frequency current-mode PWM control with adaptive slope compensation for stable regulation and fast transient response. Its dual-MOSFET architecture integrates a 0.121Ω N-channel switch and 0.188Ω P-channel synchronous rectifier, enabling up to 95% efficiency at full load.
It features closed-loop soft-start (10ms), inrush current limiting, and zero-current detection to disable the synchronous rectifier below ~50mA - eliminating reverse inductor current and improving light-load efficiency. The oscillator supports both RT-resistor programming and external synchronization via the PWM/SYNC pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Start-Up Range | 1.7V to 1.8V min - enables operation from single-cell LiFePO₄ or NiMH batteries at end-of-discharge. |
| VIN Operating Range | 0.5V to 5.5V post-start - sustains regulation even when input sags below 1V, critical for capacitor-backed supplies. |
| VOUT Adjustment Range | 2.2V to 15V - set via external resistor divider on FB pin; supports 12V analog rails and high-voltage piezo drivers. |
| Switching Frequency | 100kHz to 3MHz - adjustable via RT resistor or synchronizable to external clock for EMI-sensitive applications. |
| Quiescent Current (Burst) | 25µA - maintains high light-load efficiency without sacrificing regulation accuracy or response speed. |
| Output Disconnect | True VOUT-to-VIN isolation in shutdown - eliminates body-diode leakage and allows VOUT to fully discharge to 0V. |
| Current Limit | 1.5A typical - protects internal switches during overload while supporting ≥400mA at 5V→12V conversion. |
| Package | 12-lead 3mm × 4mm × 0.75mm DFN - thermally enhanced with exposed PGND pad requiring PCB soldering for θJC = 5°C/W. |
Pinout & Package
Package: 12-lead (3mm × 4mm) plastic DFN with exposed thermal pad (Pin 13 = PGND). Requires soldering of exposed pad to PCB ground plane for rated thermal performance (θJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (1) | Switch node | Connects to inductor; carries high di/dt; internal anti-ringing resistor activates when VOUT ≥ VIN + 2V to suppress EMI. |
| PGND (2, 13) | Power ground | Primary return path for high-current loops (inductor, output cap); exposed pad must be soldered to PCB ground plane. |
| VIN (3) | Main input supply | Supplies power to IC; accepts 0.5V–5.5V; requires ≥4.7µF ceramic bypass to PGND close to pin. |
| PWM/SYNC (4) | Mode control & sync input | High = PWM mode; Low = Burst Mode; external clock = synchronized operation; not floating. |
| VCC (5) | Internal LDO output | Regulated ~4.25V rail powering gate drivers; requires ≥4.7µF capacitor to SGND; UVLO at 1.6V disables switching. |
| RT (6) | Oscillator frequency set | Resistor to SGND programs fOSC = 57.6/RT (MHz); RT = 57.6kΩ for 1MHz nominal. |
| VC (7) | Error amplifier output | Loop compensation node; connects RC network to SGND for stability across operating conditions. |
| FB (8) | Feedback input | Monitors resistive divider from VOUT; reference = 1.202V ±24mV; sets VOUT = 1.202V × (1 + R1/R2). |
| SD (9) | Shutdown control | Logic input: >1.6V = active; <0.25V = shutdown (<1µA IQ); tolerates voltage above VIN/VOUT within abs max ratings. |
| SGND (10) | Signal ground | Reference for FB, VC, and internal circuitry; separate low-impedance path to output capacitor negative terminal. |
| VOUT (11) | Regulated output & rectifier source | Delivers regulated voltage; internal P-MOSFET source; disconnected from VIN during shutdown. |
| CAP (12) | Synchronous rectifier bias reference | Connected to 100nF cap to VOUT; generates ~5.6V below VOUT to drive P-MOSFET gate. |
Key Features
| Feature | Design Value |
|---|---|
| True output disconnect | Eliminates reverse current and body-diode conduction during shutdown - enables full VOUT discharge and prevents backfeed into VIN. |
| Adjustable Burst Mode | Reduces IQ to 25µA at no load while maintaining regulation; transitions seamlessly to PWM under load without output droop. |
| Inrush current limiting | Integrated 10ms closed-loop soft-start limits peak input surge regardless of output capacitance size or VOUT setting. |
| Wide input voltage range | Operates from 500mV after start-up - extracts maximum energy from depleted batteries or supercapacitors. |
| Robust fault protection | Includes short-circuit current foldback (1A limit), output overvoltage lockout (16.2V), thermal shutdown (170°C), and UVLO on VCC. |
| EMI-optimized switching | Anti-ringing control on SW pin and external clock synchronization support reduce radiated emissions in noise-sensitive systems. |
Applications
| Piezo Actuator Driver | PCI Express Auxiliary Rail |
|---|---|
Use Scenario: Driving high-voltage piezoelectric elements requiring precise 12V–15V excitation from a 3.3V or 5V system rail. IC Role / Device Role / Timing Role: Synchronous boost converter providing regulated, low-noise, high-PSRR output with true output disconnect to prevent actuator creep during idle. Use Value: Enables microsecond-level actuation control with minimal hold current (25µA Burst Mode) and no residual voltage leakage across the actuator. |
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: High-efficiency step-up regulator delivering up to 400mA at 12V with tight line/load regulation and fast transient response to dynamic card loads. Use Value: Eliminates need for discrete boost stages; output disconnect prevents backfeed into host supply during hot-plug events. |
| Small DC Motor Power Supply | Backup Capacitor Voltage Booster |
Use Scenario: Powering miniature 12V brushed DC motors in portable instrumentation from a single 3.7V Li-ion cell. IC Role / Device Role / Timing Role: Compact, thermally efficient boost converter delivering continuous 400mA with integrated current limiting and thermal protection. Use Value: Supports motor stall conditions without latch-up; low 500mV dropout extends runtime by utilizing full battery discharge curve. |
Use Scenario: Maintaining 12V system rail during brief AC mains interruption using a 5V supercapacitor bank. IC Role / Device Role / Timing Role: Ultra-low-quiescent boost controller that starts from 500mV and sustains regulation while capacitor discharges. Use Value: Delivers >30 seconds of hold-up time from 10F/5V capacitor; output disconnect isolates capacitor from load during normal operation. |
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 5.5A switch current; fixed 500kHz/1MHz/2.2MHz options; no true output disconnect; 16-pin QFN. | Better suited for high-current (>1A) applications but lacks VOUT-to-VIN isolation in shutdown. | Select when peak output current >600mA is required and output disconnect is not mandatory. |
| MAX17222ETA+ | Lower 0.5A current limit; 1.8V–5.5V input; 2.5V–5.25V output only; 1.2µA IQ in shutdown; 8-pin µDFN. | Targeted at ultra-low-power 3.3V/5V systems; insufficient for 12V+ outputs or >400mA loads. | Choose only for sub-5V, sub-200mA applications where footprint and IQ are primary constraints. |
Compared with TPS61088RHLR and MAX17222ETA+, the LTC3121IDE#TRPBF uniquely combines true output disconnect, 15V output capability, and 500mV minimum operating voltage - making it the only option among the three suitable for capacitor-backed 12V rail generation with zero standby leakage.
Availability
LTC3121IDE#TRPBF is available at Aetrix Electronics and suitable for piezo actuator drivers, PCIe auxiliary power supplies, small DC motor controllers, backup capacitor voltage boosters, and low-voltage battery-powered instrumentation requiring stable component supply and long-term lifecycle support.
Supply support for LTC3121IDE#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 acquired Linear Technology in 2017 and continues to develop and manufacture its high-performance analog and power management ICs under the Linear brand legacy.
The LTC3121IDE#TRPBF belongs to Linear's precision synchronous boost converter product line, designed specifically for applications demanding ultra-low input voltage operation, true output isolation, and high efficiency across wide load ranges - including energy-harvesting and capacitor-backed systems.
FAQ
What is the minimum input voltage required for the LTC3121IDE#TRPBF to start up?
The LTC3121IDE#TRPBF requires a minimum input voltage of 1.7V to 1.8V for initial start-up, as specified in the Electrical Characteristics table under "Minimum Start-Up Voltage." Once regulation is established and VOUT reaches ≥2.2V, the device continues operating down to 500mV input - a key feature for maximizing energy extraction from depleted batteries or supercapacitors. This dual-threshold behavior is intrinsic to the LTC3121IDE#TRPBF's architecture and does not require external circuitry.
Does the LTC3121IDE#TRPBF support true output disconnect, and how is it implemented?
Yes, the LTC3121IDE#TRPBF provides true output disconnect: when the SD pin is pulled low, both internal MOSFETs are turned off and the VOUT pin is isolated from VIN, allowing VOUT to fully discharge to 0V with no leakage path. This is achieved by disabling the P-channel synchronous rectifier's body diode conduction - unlike basic boost converters that rely on external diodes. The LTC3121IDE#TRPBF's CAP pin and internal gate drive scheme enable this functionality without external components.
What is the purpose of the CAP pin on the LTC3121IDE#TRPBF, and how should it be connected?
The CAP pin on the LTC3121IDE#TRPBF serves as the low-side reference for driving the internal P-channel synchronous rectifier. It must be connected via a 100nF low-ESR ceramic capacitor directly to the VOUT pin. This creates an elevated ground rail approximately 5.6V below VOUT, enabling full enhancement of the P-MOSFET gate. Incorrect CAP connection - such as omitting the capacitor or routing through high-impedance traces - will cause poor rectifier turn-off, increased conduction loss, and potential instability. This requirement is specific to the LTC3121IDE#TRPBF's gate-drive topology.
How does Burst Mode operation affect output voltage ripple on the LTC3121IDE#TRPBF?
In Burst Mode, the LTC3121IDE#TRPBF delivers energy in discrete packets until VOUT reaches regulation, then sleeps until VOUT droops ~1%, resulting in typical peak-to-peak output ripple of 1%–2%. This is higher than PWM mode ripple but enables 25µA quiescent current. To reduce ripple, add ≥10µF additional output capacitance or a 10pF–50pF feed-forward capacitor between VOUT and FB - both methods are validated in the LTC3121IDE#TRPBF's application notes and do not compromise stability.
Can the LTC3121IDE#TRPBF be synchronized to an external clock, and what are the requirements?
Yes, the LTC3121IDE#TRPBF can be synchronized to an external clock applied to the PWM/SYNC pin. The external clock frequency must be between 100kHz and 3MHz, with pulse width 100ns–2µs. An RT resistor must also be connected to program the internal oscillator to ~25% below the sync frequency (RT = 73.2 / fSYNC in kΩ). This synchronization capability is explicitly supported in the LTC3121IDE#TRPBF's oscillator architecture and is used in noise-sensitive applications like audio or RF subsystems.
LTC3121IDE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LTC3121IDE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3121IDE#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 LTC3121IDE#TRPBF reliable?
The price and inventory of LTC3121IDE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3121IDE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3121IDE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3121IDE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3121IDE#TRPBF?
LTC3121IDE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3121IDE#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 LTC3121IDE#TRPBF?
For technical support, including LTC3121IDE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3121IDE#TRPBF requirements.
6.How does Aetrix verify that LTC3121IDE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3121IDE#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 LTC3121IDE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3121IDE#TRPBF?
All LTC3121IDE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3121IDE#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 LTC3121IDE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3121IDE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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