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Analog Devices Inc. LTC3899IUHF#PBF
- Part No.:
- LTC3899IUHF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3899IUHF#PBF.pdf
- Description:
- IC REG CTRLR BUCK/BUCK-BST 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,438
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Product details
Overview
LTC3899IUHF#PBF from Analog Devices (formerly Linear Technology) is a high-performance triple-output synchronous buck/buck/boost DC/DC controller driving all-N-channel MOSFET stages. It operates from 4.5V to 60V input, delivers 29μA no-load quiescent current, supports phase-lockable switching up to 850kHz, and maintains regulation down to 2.2V input during cold-crank - enabling use in automotive start-stop and battery-powered industrial systems.
For engineers reviewing the LTC3899IUHF#PBF datasheet, LTC3899IUHF#PBF pinout, LTC3899IUHF#PBF application, or LTC3899IUHF#PBF equivalent, key selection criteria include its triple-output topology, 38-lead 5mm × 7mm QFN package with exposed thermal pad, programmable gate drive (5–10V), OPTI-LOOP® compensation, and cold-crank capability below 2.2V after startup.
Technical Context
The LTC3899IUHF#PBF implements constant-frequency current-mode control across three independent channels: two synchronous buck controllers (Channels 1 & 2) and one synchronous boost controller (Channel 3). Each channel features dedicated current-sense amplifiers, ITH error amplifiers, and independent RUN pins for sequencing.
Its architecture integrates internal top-gate bootstrap switches (eliminating external diodes), programmable DRVCC via DRVSET pin, VPRG3-selectable fixed/adjustable boost output (10V/12V/floating), and PLLIN/MODE-configurable light-load operation (Burst Mode, pulse-skipping, or forced continuous mode).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 60V operating; sustains regulation down to 2.2V after startup - critical for automotive cold-crank survival. |
| Quiescent Current | 29μA in Sleep Mode (one channel active) - extends battery runtime in always-on systems. |
| Switching Frequency | Programmable 50kHz–900kHz or phase-lockable 75kHz–850kHz - enables EMI optimization and inductor size reduction. |
| Gate Drive Voltage | Adjustable 5V–10V via DRVSET pin - supports logic-level or standard MOSFETs without external level-shifting. |
| Feedback Reference | Buck: 0.8V ±1%; Boost: 1.2V (floating), 10V (VPRG3 = GND), or 12V (VPRG3 = INTVCC) - enables flexible output configuration. |
| Max Duty Cycle | Buck: 97.5% (dropout); Boost: 99% - ensures high step-up ratio and low dropout operation. |
| Shutdown IQ | 3.6μA - minimizes standby power loss in system-level power gating. |
Pinout & Package
Package: 38-lead (5mm × 7mm) plastic QFN with exposed thermal pad (Pin 39 = GND, must be soldered to PCB). θJA = 34°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming | Resistor-to-GND sets 50–900kHz; tied to GND/INTVCC selects fixed 350/535kHz - enables precise EMI control. |
| PLLIN/MODE (Pin 2) | Synchronization & light-load mode control | Accepts external clock for phase-locking; configures Burst Mode (GND), pulse-skipping (mid-voltage), or forced CCM (INTVCC). |
| DRVSET (Pin 16) | DRVCC LDO output voltage setting | Resistor-to-GND programs 5–10V gate drive; determines UVLO thresholds - optimizes FET RDS(on) vs switching loss trade-off. |
| VPRG3 (Pin 34) | Boost output voltage mode select | Float = adjustable via VFB3; GND = fixed 10V; INTVCC = fixed 12V - simplifies design for common boost rails. |
| RUN1/RUN2/RUN3 (Pins 9/10/11) | Independent channel enable | Threshold 1.22–1.33V rising; hysteresis 75mV - enables flexible power sequencing and fault isolation. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Adapts loop response to wide range of output capacitor ESR and capacitance - eliminates need for external compensation tuning across designs. |
| No External Bootstrap Diodes | Integrated high-side driver switches eliminate discrete diodes - reduces BOM count, layout area, and reliability risk in high-density automotive PCBs. |
| Cold-Crank Operation | Maintains regulation with input as low as 2.2V after startup - meets ISO 16750-2 automotive transient requirements without auxiliary bias. |
| Triple Independent Control | Separate ITH, RUN, TRACK/SS, and SENSE per channel - enables asymmetric output configurations and independent soft-start timing. |
| Low Dropout Buck Operation | 99% duty cycle capability - supports high-VOUT/VIN ratios (e.g., 12V out from 12.5V input) in battery-fed systems. |
Applications
| Automotive Start-Stop Systems | Industrial Battery-Powered Equipment |
|---|---|
Use Scenario: Power management in vehicles with engine auto-stop/restart, requiring stable 5V/8.5V/10V rails during cranking transients. IC Role / Device Role / Timing Role: Triple-output synchronous controller managing buck-buck-boost conversion from 12V battery with cold-crank support. Use Value: Maintains regulation at 2.2V input, eliminating need for backup capacitors or secondary bias supplies during cranking. | Use Scenario: Portable test equipment needing isolated 5V, 8.5V, and regulated 10V outputs from a single Li-ion or lead-acid battery input. IC Role / Device Role / Timing Role: Primary DC/DC controller delivering three independent, sequenced, low-IQ power rails. Use Value: 29μA sleep current extends operational runtime; programmable gate drive accommodates diverse MOSFET selections. |
| Distributed DC Power Architectures | High-Reliability Embedded Controllers |
Use Scenario: Rack-mounted industrial controllers requiring multiple isolated DC rails (e.g., 5V logic, 8.5V analog, 10V sensor excitation) from a 24–48V backplane. IC Role / Device Role / Timing Role: Centralized triple-output controller replacing multiple discrete regulators to reduce footprint and component count. Use Value: Phase-lockable frequency allows synchronization across multiple LTC3899 units - suppresses beat frequencies in multi-rail systems. | Use Scenario: Avionics or railway control units demanding extended temperature operation (–40°C to 125°C) and robust transient immunity. IC Role / Device Role / Timing Role: High-reliability power controller with integrated overvoltage protection (7–13% on VFB1/2) and thermal shutdown. Use Value: Guaranteed –40°C to 125°C operation (LTC3899I grade), exposed thermal pad for enhanced heat dissipation in sealed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output synchronous controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3855IUFD#PBF | Dual-output buck-only controller; no boost channel; 32-pin QFN; max input 38V; 45μA IQ. | Cannot replace LTC3899IUHF#PBF in boost-required applications; suitable only for dual-buck systems. | Select when only two regulated rails are needed and input voltage stays ≤38V. |
| MP2965GL-Z | Triple-output buck/buck/boost controller; 40-pin QFN; 4.5–60V input; 45μA IQ; no cold-crank below 2.2V; no PLL sync. | Lacks cold-crank support and phase-lock capability - unsuitable for automotive start-stop or synchronized multi-rail EMI control. | Consider for cost-sensitive industrial applications where cold-crank and PLL are not required. |
Compared with LTC3855IUFD#PBF and MP2965GL-Z, the LTC3899IUHF#PBF uniquely combines triple buck/buck/boost topology, 2.2V cold-crank operation, phase-lockable frequency, and 29μA quiescent current - making it the only option for automotive-grade multi-rail systems requiring both boost capability and ultra-low standby power.
Availability
LTC3899IUHF#PBF is available at Aetrix Electronics and suitable for automotive start-stop systems, industrial battery-powered equipment, and distributed DC power architectures requiring stable component supply, long-term lifecycle support, and guaranteed –40°C to 125°C operation.
Supply support for LTC3899IUHF#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC3899IUHF#PBF belongs to Linear's high-voltage synchronous controller product line, designed specifically for automotive, industrial, and telecom power systems demanding wide input range, ultra-low quiescent current, and robust transient performance.
FAQ
What is the minimum input voltage the LTC3899IUHF#PBF can regulate from after startup?
The LTC3899IUHF#PBF maintains regulation with input voltages as low as 2.2V after startup, a critical feature for automotive cold-crank conditions. This capability is enabled by internal biasing from the boost output or an auxiliary supply, allowing operation far below the 4.5V nominal input range limit.
How does the VPRG3 pin affect the boost output voltage of the LTC3899IUHF#PBF?
The VPRG3 pin on the LTC3899IUHF#PBF selects the boost output mode: floating enables adjustable output via external resistors (VFB3 = 1.2V reference); GND sets fixed 10V output; INTVCC sets fixed 12V output. This eliminates external feedback dividers in standard configurations while retaining flexibility for custom voltages.
Can the LTC3899IUHF#PBF synchronize its switching frequency to an external clock?
Yes, the LTC3899IUHF#PBF supports external synchronization via the PLLIN/MODE pin (Pin 2), accepting clocks from 75kHz to 850kHz. When an external clock is applied, the rising edge of TG1 aligns with the external clock's rising edge, and all three channels operate in forced continuous conduction mode - essential for EMI reduction in multi-rail systems.
What is the purpose of the DRVSET pin on the LTC3899IUHF#PBF?
The DRVSET pin (Pin 16) programs the DRVCC gate drive voltage from 5V to 10V using a resistor to GND (50kΩ–100kΩ), or sets fixed 6V (GND) or 10V (INTVCC). It also determines UVLO thresholds and EXTVCC switchover points - enabling optimization of MOSFET conduction loss versus gate drive strength and system efficiency.
Does the LTC3899IUHF#PBF require external bootstrap diodes for high-side gate drive?
No, the LTC3899IUHF#PBF integrates internal switches in the top-gate drivers, eliminating the need for external bootstrap diodes on BOOST1/BOOST2/BOOST3 pins. This reduces component count, PCB area, and potential failure points - particularly beneficial in space-constrained automotive and industrial designs.
LTC3899IUHF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Buck-Boost
- Number of Outputs:
- 3
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 60V
- Frequency - Switching:
- 105kHz ~ 835kHz, 350kHz ~ 535kHz
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3899IUHF#PBF FAQ
1.How can I place an order for LTC3899IUHF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3899IUHF#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 LTC3899IUHF#PBF reliable?
The price and inventory of LTC3899IUHF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3899IUHF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3899IUHF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3899IUHF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3899IUHF#PBF?
LTC3899IUHF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3899IUHF#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 LTC3899IUHF#PBF?
For technical support, including LTC3899IUHF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3899IUHF#PBF requirements.
6.How does Aetrix verify that LTC3899IUHF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3899IUHF#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 LTC3899IUHF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3899IUHF#PBF?
All LTC3899IUHF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3899IUHF#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 LTC3899IUHF#PBF part is unused and in its original packaging.
Return procedure for LTC3899IUHF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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