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Analog Devices Inc. LTC3891IUDC#TRPBF
- Part No.:
- LTC3891IUDC#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC3891IUDC#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:6,934
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Product details
Overview
LTC3891IUDC#TRPBF from Analog Devices (formerly Linear Technology) is a high-performance, low-quiescent-current synchronous step-down DC/DC controller driving all-N-channel MOSFETs. It operates across 4V–60V input, delivers 0.8V–24V output, supports phase-lockable switching up to 750kHz, and features OPTI-LOOP® compensation for optimized transient response in battery-powered and automotive always-on systems.
For engineers reviewing the LTC3891IUDC#TRPBF datasheet, LTC3891IUDC#TRPBF pinout, LTC3891IUDC#TRPBF application, or LTC3891IUDC#TRPBF equivalent, key selection criteria include its 50μA no-load IQ, selectable light-load modes (Burst/Pulse-Skipping/Continuous), RSENSE or DCR current sensing, 99% duty cycle dropout capability, and integrated 5.1V INTVCC LDO with EXTVCC switchover.
Technical Context
The LTC3891IUDC#TRPBF implements a constant-frequency current-mode control architecture with an internal transconductance error amplifier (gm = 2 mmho) and precision 0.8V reference (±1.2mV over temperature). Its PLLIN/MODE pin configures light-load behavior-Burst Mode (grounded), pulse-skipping (1.2V–INTVCC−1.3V), or forced continuous (tied to INTVCC)-enabling trade-offs between efficiency and ripple.
It integrates dual gate drivers (TG/BG) with <2.5Ω on-resistance, 25ns transition times, and synchronized dead-time control (30ns min). The internal INTVCC regulator switches between VIN- and EXTVCC-derived 5.1V supply based on EXTVCC voltage (>4.7V threshold), supporting efficient multi-rail power architectures.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 60V - supports wide intermediate bus and battery chemistries including 12V, 24V, and 48V systems. |
| Output Voltage Range | 0.8V to 24V - programmable via external resistor divider; regulated by 0.800V ±0.8% reference. |
| No-Load Quiescent Current | 50μA - extends runtime in battery-powered applications such as portable instrumentation and telematics. |
| Switching Frequency Range | 75kHz to 750kHz - phase-lockable to external clock or programmable via FREQ pin resistor (50–900kHz). |
| Current Sense Threshold | 22mV to 85mV - selectable via ILIM pin (GND/FLOAT/INTVCC) to match sense resistor or DCR network. |
| Power Good Accuracy | ±10% VFB trip level with 2.5% hysteresis - provides reliable output voltage monitoring for system sequencing. |
| Shutdown Current | <14μA - achieved when RUN pin is pulled below 0.7V, enabling ultra-low-power standby states. |
Pinout & Package
Package: 20-lead (3mm × 4mm) plastic QFN (UDC), exposed pad (Pin 21) soldered to SGND for thermal performance (θJA = 43°C/W). RoHS-compliant, lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGOOD | Open-drain status output | Asserts low when VFB deviates >10% from setpoint; requires external pull-up for logic-level interfacing. |
| VFB | Feedback input | Compares output voltage (via resistive divider) against 0.800V internal reference to regulate output. |
| ITH | Error amplifier output / compensation node | Controls peak inductor current; connects to RC network for OPTI-LOOP® compensation tuning. |
| TG, BG | Top/bottom gate drivers | Drive N-channel MOSFETs with 2.5Ω pull-up/pull-down; TG swings referenced to SW node. |
| SENSE+, SENSE− | Differential current sense inputs | Measure current via RSENSE or DCR; enable accurate cycle-by-cycle current limiting and foldback. |
| TRACK/SS | Soft-start and tracking input | Internal 10μA pull-up charges external capacitor for controlled ramp-up; supports voltage tracking of other rails. |
| PLLIN/MODE | Light-load mode select | Configures Burst Mode (GND), pulse-skipping (mid-voltage), or forced continuous (INTVCC) operation. |
| FREQ | Oscillator frequency programming | Resistor-to-GND sets frequency from 50kHz–900kHz; internal 20μA current source enables simple scaling. |
| ILIM | Current limit threshold select | Three levels (22/43/64mV typ) selected by tying to GND/FLOAT/INTVCC for flexible overcurrent protection. |
| RUN | Enable/shutdown control | 1.16V threshold for soft shutdown; 0.7V for deep shutdown (<14μA IQ); includes 7μA internal pull-up. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Allows stable loop response across wide range of output capacitors (including high-ESR electrolytics) without redesign. |
| Selectably Low-Ripple Light-Load Operation | Pulse-skipping or forced continuous mode maintains low output ripple at light loads, critical for noise-sensitive analog/audio circuits. |
| 99% Maximum Duty Cycle | Enables ultra-low dropout operation (e.g., 12V→11.5V), preserving regulation during brownout or cold-cranking conditions. |
| Integrated Dual LDO Architecture | Automatic switchover between VIN- and EXTVCC-derived 5.1V INTVCC reduces power loss and improves efficiency in multi-output designs. |
| Programmable Current Limit with Foldback | Three preset thresholds plus foldback during short-circuit reduce MOSFET thermal stress without external circuitry. |
| Robust Start-Up Sequencing Support | TRACK/SS pin enables precise soft-start timing or rail tracking-essential for FPGA, ASIC, and multi-core processor power sequencing. |
Applications
| Automotive Infotainment Power Supply | Industrial IoT Sensor Node |
|---|---|
|
Use Scenario: Powering 3.3V/5V logic and RF modules in vehicle head units with 9V–16V battery input and cold-crank down to 4.5V. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating intermediate bus; manages start-up sequencing via TRACK/SS and monitors health via PGOOD. Use Value: 50μA quiescent current prevents battery drain during vehicle sleep; 60V abs max rating withstands load dump transients. |
Use Scenario: Battery-powered edge sensor node requiring long-life operation from Li-ion or 2xAA cells with variable input (2.7V–12V). IC Role / Device Role / Timing Role: High-efficiency step-down controller delivering stable 1.8V/3.3V to MCU and wireless SoC; uses Burst Mode to minimize idle current. Use Value: 50μA no-load IQ extends battery life to years; wide VIN accommodates full discharge curve without external pre-regulator. |
| Telecom Intermediate Bus Converter | Medical Portable Diagnostic Equipment |
|
Use Scenario: Converting 48V backplane to 12V/5V intermediate rails in compact telecom line cards with strict thermal limits. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller synchronized to system clock via PLLIN/MODE; drives discrete MOSFETs for layout flexibility. Use Value: Phase-lockable 750kHz operation enables EMI reduction through spread-spectrum synchronization; 20-pin QFN minimizes board area. |
Use Scenario: Powering precision analog front-end, ADC, and low-noise amplifiers in handheld ultrasound or glucose meters. IC Role / Device Role / Timing Role: Low-noise, tightly regulated 3.3V supply with programmable soft-start to prevent inrush-induced signal corruption. Use Value: Pulse-skipping mode ensures low output ripple independent of load; 0.8V reference accuracy (±0.8%) guarantees measurement integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3892IUDC#TRPBF | Dual-phase controller with identical 4V–60V input, but adds phase interleaving, current sharing, and dual ITH pins. | Required for higher current (>20A) or lower ripple demands where single-phase is insufficient. | Select LTC3892IUDC#TRPBF only when dual-phase operation, current balancing, or higher total output power is needed. |
| MP2491DJ-LF-P | Monolithic 60V buck converter (integrated MOSFETs); 100μA IQ; fixed 3.3V/5V/12V options; no TRACK/SS or PLLIN. | Suitable for cost-sensitive, space-constrained designs where external FETs are unnecessary and programmability is secondary. | Choose MP2491DJ-LF-P for simplified BOM and layout when output voltage is fixed and peak current ≤5A. |
Compared with LTC3891IUDC#TRPBF, the LTC3892IUDC#TRPBF adds dual-phase capability at the cost of increased complexity and pin count, while the MP2491DJ-LF-P trades programmability and ultra-low IQ for integration and lower bill-of-materials cost.
Availability
LTC3891IUDC#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial IoT sensor nodes, and telecom intermediate bus converters requiring stable component supply, long-lifecycle support, and AEC-Q100-aligned reliability.
Supply support for LTC3891IUDC#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3891 belongs to Linear's high-voltage monolithic and controller product line, designed specifically for robust, high-efficiency DC/DC conversion in harsh environments-including automotive always-on, battery backup, and wide-input industrial power systems.
FAQ
What is the operating junction temperature range for the LTC3891IUDC#TRPBF?
The LTC3891IUDC#TRPBF is rated for –40°C to 125°C operating junction temperature. This grade ('I') is guaranteed over the full range, with maximum junction temperature limited to 125°C. Thermal design must account for θJA = 43°C/W (QFN package) and power dissipation to maintain safe operation within this envelope. The LTC3891IUDC#TRPBF datasheet specifies electrical characteristics under these conditions.
How does the LTC3891IUDC#TRPBF achieve 50μA quiescent current?
The LTC3891IUDC#TRPBF achieves 50μA no-load IQ through adaptive biasing and selective circuit disabling in light-load conditions-particularly in Burst Mode operation, where internal blocks (oscillator, drivers, comparators) are gated off between bursts. This ultra-low IQ is measured at VIN = 12V, VFB = 0.83V, and no output load. The LTC3891IUDC#TRPBF maintains this specification across its full temperature range.
Can the LTC3891IUDC#TRPBF be synchronized to an external clock?
Yes, the LTC3891IUDC#TRPBF supports external synchronization via the PLLIN/MODE pin. When an external clock is applied, the internal phase-locked loop aligns the rising edge of the TG signal to the external clock's rising edge, enabling EMI reduction and multi-rail coherence. The LTC3891IUDC#TRPBF accepts 75kHz–750kHz external clocks and forces forced continuous conduction mode during sync.
What is the purpose of the EXTVCC pin on the LTC3891IUDC#TRPBF?
The EXTVCC pin on the LTC3891IUDC#TRPBF allows the internal 5.1V INTVCC regulator to be powered from an external supply (e.g., another converter's output) instead of VIN, improving overall system efficiency. When EXTVCC exceeds 4.7V, the device automatically switches from the VIN-based LDO to the EXTVCC-based LDO. The LTC3891IUDC#TRPBF tolerates up to 14V on EXTVCC and requires proper decoupling per the datasheet.
Does the LTC3891IUDC#TRPBF support output voltage tracking during start-up?
Yes, the LTC3891IUDC#TRPBF supports precise output voltage tracking via the TRACK/SS pin. By connecting a resistor divider from a master supply to the TRACK/SS pin, the LTC3891IUDC#TRPBF regulates its VFB to match the TRACK/SS voltage-ensuring coordinated ramp-up with other rails. An internal 10μA current source also enables soft-start via a capacitor to ground. This functionality is fully specified and tested for the LTC3891IUDC#TRPBF.
LTC3891IUDC#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 60V
- Frequency - Switching:
- 105kHz ~ 835kHz, 350kHz ~ 535kHz
- Duty Cycle (Max):
- 99%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (3x4)
LTC3891IUDC#TRPBF FAQ
1.How can I place an order for LTC3891IUDC#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3891IUDC#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 LTC3891IUDC#TRPBF reliable?
The price and inventory of LTC3891IUDC#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3891IUDC#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3891IUDC#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3891IUDC#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3891IUDC#TRPBF?
LTC3891IUDC#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3891IUDC#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 LTC3891IUDC#TRPBF?
For technical support, including LTC3891IUDC#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3891IUDC#TRPBF requirements.
6.How does Aetrix verify that LTC3891IUDC#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3891IUDC#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 LTC3891IUDC#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3891IUDC#TRPBF?
All LTC3891IUDC#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3891IUDC#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 LTC3891IUDC#TRPBF part is unused and in its original packaging.
Return procedure for LTC3891IUDC#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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