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Analog Devices Inc. LTC3858IUH#TRPBF
- Part No.:
- LTC3858IUH#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3858IUH#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,097
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Product details
Overview
LTC3858IUH#TRPBF from Analog Devices (formerly Linear Technology) is a dual-phase, synchronous step-down DC/DC controller IC driving two independent N-channel MOSFET stages. It delivers 3.3V/5A and 8.5V/3.5A outputs from a 4V–38V input, features 170μA quiescent current in single-channel sleep mode, 0.8V reference accuracy (±1.5%), and out-of-phase operation to reduce input ripple. It is used in battery-powered digital systems requiring high-efficiency dual-rail power conversion.
For engineers reviewing the LTC3858IUH#TRPBF datasheet, LTC3858IUH#TRPBF pinout, LTC3858IUH#TRPBF application, or LTC3858IUH#TRPBF equivalent, key selection criteria include phase-lockable frequency (75–850 kHz), RSENSE/DCR current sensing, OPTI-LOOP® compensation, selectable light-load modes (Burst/Pulse-Skipping/Forced Continuous), and dual independent soft-start with short-circuit latch-off protection.
Technical Context
The LTC3858IUH#TRPBF implements a constant-frequency current-mode architecture with two fully independent control loops operating 180° out of phase. Each channel uses an error amplifier (EA) comparing VFB to a precision 0.800V reference, generating ITH voltage that sets peak inductor current via differential current comparators referenced to SENSE+ and SENSE− pins.
It integrates dual gate drivers (TG/BG) with 2.5Ω pull-up and 1.5Ω pull-down on TG, supports external EXTVCC switchover (4.7V threshold), and includes dedicated PLLIN/MODE pin for synchronization or light-load mode selection-ground for Burst Mode®, INTVCC for forced continuous, or mid-voltage for pulse-skipping.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 38V - supports wide-input industrial, automotive, and battery-based intermediate bus systems. |
| Quiescent Current (1 ch active) | 170μA typical - extends runtime in always-on or low-duty-cycle battery-powered applications. |
| Feedback Reference Voltage | 0.800V ±1.5% over –40°C to 125°C - enables accurate output regulation across temperature without external trimming. |
| Switching Frequency Range | 75kHz–850kHz (phase-lockable) or 50kHz–900kHz (programmable) - allows EMI optimization and inductor size trade-offs. |
| Duty Cycle Max | 99.4% - supports ultra-low dropout operation down to VIN − VOUT ≈ 0.3V at high load. |
| Current Sense Threshold | 22–86mV (selectable via ILIM pin) - accommodates both low-RDS(on) DCR sensing and discrete RSENSE solutions. |
| PGOOD Accuracy | ±10% trip threshold with 2.5% hysteresis - provides reliable power-good signaling for system sequencing and fault detection. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed thermal pad (Pin 33 = SGND). Requires soldering of exposed pad to PCB for thermal performance (θJA = 34°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1– / SENSE2– (1, 9) | Differential current sense (–) input | Supplies bias current when > INTVCC – 0.5V; sets common-mode range for accurate current measurement. |
| FREQ (2) | Oscillator frequency programming | 20μA internal pull-up enables resistor-based frequency setting from 50kHz to 900kHz. |
| PHASMD (3) | Phase relationship selector | Configures TG2/CLKOUT phase offset relative to TG1 (180°/240°/floating default = 180°). |
| CLKOUT (4) | Synchronization clock output | INTVCC-rail-to-ground square wave for daisy-chaining additional PolyPhase® controllers. |
| PLLIN/MODE (5) | Sync input / light-load mode control | Accepts external clock for phase-locking; selects Burst Mode® (GND), pulse-skipping (mid-voltage), or forced continuous (INTVCC). |
| SGND (6, 33) | Small-signal ground reference | Must be routed separately from PGND to avoid noise coupling into feedback and current sense paths. |
| RUN1 / RUN2 (7, 8) | Independent channel enable | Logic-level shutdown: <1.23V disables channel; both <0.7V enables ultra-low-IQ shutdown (8μA). |
| BOOST1 / BOOST2 (17, 24) | Floating top-gate bootstrap supply | Swings from INTVCC to (VIN + INTVCC); requires external Schottky diode and capacitor per channel. |
| TG1 / TG2 (15, 26) | Top N-MOSFET gate drive output | High-side floating driver with 25ns rise/fall time (3300pF load); voltage swing = INTVCC – 0.5V superimposed on SW node. |
| BG1 / BG2 (18, 23) | Bottom N-MOSFET gate drive output | Low-side driver with 28ns rise/13ns fall time (3300pF load); rail-to-rail swing from GND to INTVCC. |
| SW1 / SW2 (16, 25) | Power switch node connection | Direct connection to inductor and MOSFET source/drain; high dv/dt node requiring careful layout and snubbing. |
| PGND (21) | Power ground return | Return path for bottom MOSFET sources and input capacitor negative terminals; must be low-inductance connection. |
| VIN (22) | Main input supply | Primary power source for internal LDO and gate drivers; bypassed with ceramic capacitor to SGND. |
| EXTVCC (20) | External auxiliary supply input | Enables switchover to external 4.7–14V source to power INTVCC, improving efficiency vs. VIN-derived LDO. |
| INTVCC (19) | Internal LDO output (5.1V) | Powers control circuitry and gate drivers; requires ≥4.7μF low-ESR ceramic decoupling to PGND. |
| VFB1 / VFB2 (11, 31) | Output voltage feedback input | Compares remote-sensed output voltage (via resistive divider) to 0.800V reference for regulation. |
| ITH1 / ITH2 (12, 30) | Error amplifier output / compensation node | Controls current limit threshold; connects to RC network for OPTI-LOOP® compensation tuning. |
| SS1 / SS2 (13, 29) | Soft-start and short-circuit timer | 1μA internal pull-up charges external capacitor for linear VOUT ramp; also discharges at 9μA during short-circuit to trigger latch-off. |
| PGOOD1 / PGOOD2 (14, 27) | Open-drain power-good indicator | Asserts low when VFB deviates >±10% from setpoint; includes 25μs fault reporting delay. |
| ILIM (28) | Current limit threshold select | Three-level selection (GND/FLOAT/INTVCC) sets max sense voltage to 22/43/64mV for flexible current sensing design. |
Key Features
| Feature | Design Value |
|---|---|
| Out-of-phase dual-channel operation | Reduces RMS input capacitor current by ~30% and lowers conducted EMI compared to in-phase controllers. |
| OPTI-LOOP® compensation | Enables stable loop response across wide ranges of output capacitance (10μF–1000μF) and ESR without redesign. |
| Independent soft-start and latch-off | Each channel has dedicated SS pin enabling staggered startup and autonomous short-circuit shutdown without cross-talk. |
| Programmable current sense threshold | ILIM pin selects 22/43/64mV thresholds - matches low-value DCR networks or milliohm RSENSE while preserving noise immunity. |
| Ultra-low dropout operation | 99.4% max duty cycle allows regulation with VIN as low as VOUT + 0.3V, critical for Li-ion and 12V bus applications. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC Dual-Rail Converter |
|---|---|
Use Scenario: Powers 3.3V microcontroller and 8.5V display backlight from 9–16V vehicle battery with cold-crank tolerance. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent 3.3V/5A and 8.5V/3.5A rails with out-of-phase switching to minimize input ripple. Use Value: 170μA IQ extends standby time; 4V–38V VIN range handles load-dump transients; PGOOD outputs enable safe MCU boot sequencing. | Use Scenario: Generates isolated 3.3V logic and 8.5V I/O rails from 24V DC industrial bus in programmable logic controller. IC Role / Device Role / Timing Role: High-efficiency dual-output controller with phase modulation to suppress input ripple-induced noise in analog signal chains. Use Value: OPTI-LOOP® ensures stability with diverse output capacitors; latch-off protection prevents damage during field-wiring faults. |
| Portable Medical Diagnostic Device | Distributed Telecom Power System |
Use Scenario: Powers FPGA core (3.3V) and ADC front-end (8.5V) from rechargeable Li-ion pack (3.0–4.2V/cell × 3S). IC Role / Device Role / Timing Role: Dual-channel step-down controller supporting wide VIN (4–38V), using Burst Mode® to maintain >85% efficiency at 1mA load. Use Value: 8μA shutdown current preserves battery life during idle; independent RUN pins allow dynamic rail enable/disable for power gating. | Use Scenario: Provides local 3.3V and 8.5V supplies from 48V telecom backplane in distributed base station radio unit. IC Role / Device Role / Timing Role: Synchronous buck controller with phase-lockable frequency (75–850kHz) synchronized to system clock to eliminate beat frequencies. Use Value: CLKOUT pin enables multi-phase expansion; EXTVCC support allows efficient use of intermediate 12V rail to power INTVCC. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-phase synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3858-1IUH#TRPBF | Fixed current limit (no ILIM pin), single PGOOD output, no phase modulation or CLKOUT pin. | Targeted at cost-sensitive, non-synchronized dual-rail systems where phase control and daisy-chaining are unnecessary. | Select only if simplified feature set suffices and system does not require synchronization or independent current limit tuning. |
| MP8770GL-Z | Single-channel, integrated MOSFETs (40V/8A), no external gate drivers; lacks dual independent soft-start and latch-off. | Used in space-constrained, lower-power applications where integration outweighs flexibility and fault robustness. | Choose when board area is critical and dual-rail independence, ultra-low IQ, or short-circuit latch-off are not required. |
Compared with LTC3858-1IUH#TRPBF and MP8770GL-Z, the LTC3858IUH#TRPBF uniquely combines dual independent control loops, programmable current sensing, phase synchronization capability, and robust fault protection-making it optimal for high-reliability, multi-rail industrial and automotive power designs.
Availability
LTC3858IUH#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLCs, and portable medical devices requiring stable component supply, extended temperature operation (–40°C to 125°C), and long-term lifecycle support.
Supply support for LTC3858IUH#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 maintains its high-performance power management portfolio with rigorous qualification and long-term product support.
The LTC3858IUH#TRPBF belongs to Linear's PolyPhase® synchronous controller family, designed specifically for high-efficiency, multi-phase, dual-output DC/DC conversion in demanding industrial, automotive, and telecom applications.
FAQ
What is the operating junction temperature range for the LTC3858IUH#TRPBF?
The LTC3858IUH#TRPBF is guaranteed over the full –40°C to 125°C operating junction temperature range. This I-grade qualification ensures reliable performance in under-hood automotive, industrial control, and outdoor telecom environments where ambient temperatures exceed commercial limits. Thermal design must account for θJA = 34°C/W and proper soldering of the exposed pad (Pin 33) to SGND.
How does the LTC3858IUH#TRPBF achieve ultra-low quiescent current in battery-powered systems?
The LTC3858IUH#TRPBF achieves 170μA quiescent current with one channel active and 8μA in full shutdown by combining a low-leakage internal architecture, optimized biasing of control circuits, and intelligent gate driver power management. Its internal LDO (INTVCC) can be powered from EXTVCC to bypass less-efficient VIN-derived regulation, further reducing system-level power loss during light-load operation.
Can the LTC3858IUH#TRPBF synchronize to an external clock, and how is this configured?
Yes, the LTC3858IUH#TRPBF supports external synchronization via the PLLIN/MODE pin (Pin 5). Applying a clean external clock signal (75–850kHz) to this pin engages the internal phase-locked loop, forcing the rising edge of TG1 to align with the rising edge of the external clock. This eliminates beat frequencies in multi-controller systems and simplifies EMI filtering in dense power architectures.
What protection features does the LTC3858IUH#TRPBF provide against output short circuits?
The LTC3858IUH#TRPBF provides dual-layer short-circuit protection: (1) foldback current limiting that progressively reduces peak current as VOUT drops below 70% of nominal, and (2) independent latch-off shutdown triggered when the SS pin voltage falls below 1.5V after arming above 2V. Both channels operate autonomously, preventing fault propagation between rails.
Does the LTC3858IUH#TRPBF support both RSENSE and DCR current sensing, and how is sensing selected?
Yes, the LTC3858IUH#TRPBF supports both RSENSE and DCR current sensing through its differential SENSE+ and SENSE− inputs. No configuration pin is required-the same interface works for either method. The ILIM pin (Pin 28) selects one of three maximum sense voltage thresholds (22/43/64mV) to match the expected signal level from the chosen sensing technique, ensuring optimal SNR and accuracy across load conditions.
LTC3858IUH#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 32-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:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 38V
- Frequency - Switching:
- 105kHz ~ 835kHz, 350kHz ~ 535kHz
- Duty Cycle (Max):
- 99.4%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
LTC3858IUH#TRPBF FAQ
1.How can I place an order for LTC3858IUH#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3858IUH#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 LTC3858IUH#TRPBF reliable?
The price and inventory of LTC3858IUH#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3858IUH#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3858IUH#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3858IUH#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3858IUH#TRPBF?
LTC3858IUH#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3858IUH#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 LTC3858IUH#TRPBF?
For technical support, including LTC3858IUH#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3858IUH#TRPBF requirements.
6.How does Aetrix verify that LTC3858IUH#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3858IUH#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 LTC3858IUH#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3858IUH#TRPBF?
All LTC3858IUH#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3858IUH#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 LTC3858IUH#TRPBF part is unused and in its original packaging.
Return procedure for LTC3858IUH#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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