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Analog Devices Inc. LTC3858IUH-2#TRPBF
- Part No.:
- LTC3858IUH-2#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3858IUH-2#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,601
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Product details
Overview
LTC3858IUH-2#TRPBF from Analog Devices (formerly Linear Technology) is a dual-phase, synchronous step-down DC/DC controller IC designed for high-efficiency intermediate bus conversion. It delivers two independent output rails (e.g., 3.3V/5A and 8.5V/3.5A), supports 4V–38V input, achieves 99% duty cycle in dropout, and operates with 170μA quiescent current (one channel active) - ideal for battery-powered digital systems requiring ultra-low standby power.
For engineers reviewing the LTC3858IUH-2#TRPBF datasheet, LTC3858IUH-2#TRPBF pinout, LTC3858IUH-2#TRPBF application, or LTC3858IUH-2#TRPBF equivalent, key selection criteria include out-of-phase dual-channel operation to reduce input ripple, OPTI-LOOP® compensation for wide capacitor ESR tolerance, programmable 50kHz–900kHz switching frequency, and selectable light-load modes (Burst Mode®, pulse-skipping, forced continuous).
Technical Context
The LTC3858IUH-2#TRPBF implements a constant-frequency current-mode architecture with two independent N-channel MOSFET gate drivers operating 180° out of phase. Its dual-loop control uses VFB-sensed output voltage and SENSE± differential current sensing (RSENSE or DCR) to regulate each channel's peak inductor current via ITH voltage.
It integrates an internal 5.1V LDO (INTVCC) powered from VIN or EXTVCC (switchover at 4.7V), supports external synchronization via PLLIN/MODE, and disables overvoltage crowbar and short-circuit latchoff - distinguishing it from LTC3858 and LTC3858-1 variants. Phase relationship is configurable via PHASMD pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports 12V/24V industrial buses and wide-range battery chemistries (Li-ion, lead-acid, 4S–10S). |
| Quiescent Current (1 ch active) | 170μA typical - extends runtime in always-on battery systems without compromising regulation accuracy. |
| Feedback Reference Voltage | 0.800V ±12mV (–40°C to 125°C) - enables precise output setting down to 0.8V with standard resistor dividers. |
| Switching Frequency Range | 50kHz to 900kHz (programmable) - balances efficiency, size, and EMI; supports synchronization to external clock (75–850kHz). |
| Duty Cycle Max | 99% - maintains regulation during deep dropout (e.g., VIN = 3.6V → VOUT = 3.3V), critical for low-VIN edge cases. |
| Current Sense Threshold | 22–86mV (selectable via ILIM pin) - allows optimization of sense resistor power loss vs. noise immunity across load ranges. |
| Operating Junction Temp | –40°C to 125°C - qualified for automotive under-hood and industrial embedded environments. |
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 | Connects to low-side of RSENSE or DCR network; supplies bias current above INTVCC – 0.5V. |
| FREQ (2) | Oscillator frequency programming | 20μA pull-up sets VCO frequency; 0V = 350kHz, INTVCC = 535kHz, resistor-to-GND enables 50–900kHz tuning. |
| PHASMD (3) | Phase relationship selector | Configures TG2/CLKOUT phase offset relative to TG1: GND = 180°/60°, INTVCC = 240°/120°, float = 180°/90°. |
| CLKOUT (4) | Synchronization output | Open-drain INTVCC-to-GND clock signal for daisy-chaining additional PolyPhase controllers. |
| PLLIN/MODE (5) | Sync input / light-load mode select | Accepts external clock (75–850kHz); also selects Burst Mode® (GND), pulse-skipping (1.2–3.8V), or forced continuous (INTVCC). |
| SGND (6, 33) | Small-signal ground reference | Mandatory separate routing from PGND; exposed pad must be soldered for thermal and noise integrity. |
| RUN1 / RUN2 (7, 8) | Independent channel enable | <1.26V disables respective channel; both <0.7V enters 8μA shutdown with INTVCC LDO off. |
| BOOST1 / BOOST2 (17, 24) | Top-gate bootstrap supply | Swings from INTVCC to (VIN + INTVCC); requires external bootstrap capacitor and Schottky diode. |
| TG1 / TG2 (15, 26) | Top N-MOSFET gate drive | Floating driver output; voltage swing = INTVCC – 0.5V superimposed on SW node. |
| BG1 / BG2 (18, 23) | Bottom N-MOSFET gate drive | Ground-referenced driver; swings from 0V to INTVCC (2.4Ω pull-up / 1.1Ω pull-down). |
| SW1 / SW2 (16, 25) | Switch node connection | Direct connection to inductor high-side; ties to BOOST capacitor and external top MOSFET drain. |
| VIN (22) | Main input supply | 4V–40V absolute max; powers internal VIN LDO for INTVCC when EXTVCC is inactive or <4.7V. |
| EXTVCC (20) | External INTVCC supply input | Enables higher-efficiency INTVCC sourcing from secondary rail (e.g., 5V output); switchover at 4.7V ±250mV. |
| PGOOD1 / PGOOD2 (14, 27) | Open-drain power-good flag | Asserts low when VFB deviates >±10% from 0.8V; includes 2.5% hysteresis for noise immunity. |
| VFB1 / VFB2 (11, 31) | Output voltage feedback input | High-impedance (±50nA) node referenced to 0.800V internal bandgap; used with external resistor divider. |
| ITH1 / ITH2 (12, 30) | Error amplifier output / current limit control | Controls peak inductor current trip point; voltage range 0.425V–2V defines current limit and transient response. |
| SS1 / SS2 (13, 29) | Soft-start / tracking input | Internal 1μA pull-up charges external capacitor for linear ramp; also accepts resistor divider for supply tracking. |
| ILIM (28) | Current limit threshold select | Three levels (22/43/64mV typ) set by tying to SGND/FLOAT/INTVCC - adjusts sense gain without changing RSENSE. |
Key Features
| Feature | Design Value |
|---|---|
| Out-of-phase dual-channel operation | Reduces RMS input capacitor current by ~30% and lowers conducted EMI versus in-phase designs. |
| OPTI-LOOP® compensation | Enables stable loop response across wide COUT values (10μF–1000μF) and ESR (0.5mΩ–50mΩ) without re-tuning. |
| Selectably disabled OVP crowbar | Eliminates forced bottom-FET turn-on during overvoltage events - prevents uncontrolled discharge and improves fault behavior. |
| Independent soft-start and tracking | SS1/SS2 pins allow staggered startup or precise voltage sequencing (e.g., core before I/O) without external circuitry. |
| Low-noise current sensing | SENSE± inputs reject common-mode noise up to 28V and support Kelvin-connected DCR networks for accurate lossless sensing. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
|
Use Scenario: Dual-rail power for SoC (1.1V core, 3.3V I/O) and display interface (5V, 12V) in head-unit design with 9–16V battery input. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent 3.3V/5A and 8.5V/3.5A outputs with out-of-phase switching to minimize input ripple. Use Value: 170μA IQ extends battery backup time; 99% duty cycle sustains 3.3V output during cold-crank (VIN dips to 6V). |
Use Scenario: Distributed 5V and 24V auxiliary rails in modular PLC backplane, fed from 48V intermediate bus. IC Role / Device Role / Timing Role: High-voltage step-down controller supporting 4V–38V input, driving discrete N-MOSFETs for robust 5V/10A and 24V/2A outputs. Use Value: Wide VIN range eliminates need for pre-regulator; programmable frequency avoids sensitive EMI bands in noisy factory environments. |
| Portable Medical Imaging Sensor | 5G Small Cell Remote Radio Unit |
|
Use Scenario: Battery-powered ultrasound probe requiring low-noise 1.8V analog and 3.3V digital rails with minimal standby drain. IC Role / Device Role / Timing Role: Ultra-low-IQ dual controller enabling Burst Mode® operation to maintain <1mA total system sleep current. Use Value: 8μA shutdown current preserves Li-ion capacity during transport; independent RUN pins allow selective subsystem wake-up. |
Use Scenario: Compact remote radio unit needing efficient 3.3V FPGA core and 12V PA bias from 28V telecom supply. IC Role / Device Role / Timing Role: Synchronous buck controller with EXTVCC support - derives INTVCC from its own 3.3V rail to improve overall system efficiency. Use Value: Eliminates dedicated LDO for gate drivers; phase-lockable frequency enables deterministic EMI alignment with baseband clock. |
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 |
|---|---|---|---|
| LTC3858EUH-2#TRPBF | Same silicon, rated for 0°C to 85°C junction temperature (vs. –40°C to 125°C for I-grade). | Not suitable for extended-temperature industrial or automotive under-hood use. | Select only for commercial-temperature applications where cost sensitivity outweighs thermal margin. |
| MP8772GQ-Z | Single-channel, 4V–60V input, integrated MOSFETs; no phase-sync or dual-output capability. | Lacks dual independent outputs and out-of-phase operation - cannot replace LTC3858IUH-2#TRPBF in multi-rail systems. | Consider only for single-rail, space-constrained designs where integration outweighs flexibility. |
Compared with LTC3858EUH-2#TRPBF, the LTC3858IUH-2#TRPBF provides guaranteed operation down to –40°C and up to 125°C, essential for harsh environments; compared with MP8772GQ-Z, it offers true dual-channel control, external MOSFET flexibility, and PolyPhase synchronization - critical for high-current, low-noise, multi-rail power architectures.
Availability
LTC3858IUH-2#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC modules, portable medical sensors, and 5G remote radio units requiring stable component supply, long-term lifecycle assurance, and extended temperature qualification.
Supply support for LTC3858IUH-2#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 full product support, documentation, and manufacturing continuity for all Linear power management ICs.
The LTC3858IUH-2#TRPBF belongs to Linear's high-performance synchronous controller family, engineered for efficiency-critical, multi-rail DC/DC conversion in battery-powered, automotive, and industrial systems where low IQ, wide VIN, and flexible light-load operation are mandatory.
FAQ
What is the key functional difference between LTC3858IUH-2#TRPBF and the standard LTC3858?
The LTC3858IUH-2#TRPBF disables the overvoltage protection crowbar (BG forced-on) and short-circuit latchoff features present in the base LTC3858. This results in more predictable fault recovery and avoids uncontrolled discharge during overvoltage transients - beneficial in systems where graceful degradation is preferred over hard shutdown.
Does LTC3858IUH-2#TRPBF support external synchronization, and how is it implemented?
Yes, LTC3858IUH-2#TRPBF supports external synchronization via the PLLIN/MODE pin. Applying a clean CMOS/TTL clock (75–850kHz) to this pin locks the rising edge of TG1 to the rising edge of the external signal. The internal phase-locked loop ensures jitter-free alignment, enabling deterministic EMI reduction in multi-controller systems.
How does the ILIM pin affect current limit configuration in LTC3858IUH-2#TRPBF?
The ILIM pin on LTC3858IUH-2#TRPBF selects one of three maximum current sense thresholds: 22mV (ILIM = SGND), 43mV (ILIM = FLOAT), or 64mV (ILIM = INTVCC). This allows designers to retain the same RSENSE value while scaling current limit across different load requirements - simplifying BOM management and layout reuse.
Can LTC3858IUH-2#TRPBF operate with only one channel enabled, and what is its quiescent current in that state?
Yes, LTC3858IUH-2#TRPBF supports independent channel control via RUN1 and RUN2 pins. With one channel active and the other shut down, typical quiescent current is 170μA in Sleep Mode (Burst Mode® enabled), making it highly suitable for asymmetric power architectures where only one rail is active during standby.
What thermal considerations apply to the exposed pad (Pin 33) of LTC3858IUH-2#TRPBF?
The exposed pad (Pin 33) of LTC3858IUH-2#TRPBF is electrically and thermally connected to SGND. It must be soldered to a minimum 200mm² copper pour with ≥4 thermal vias (0.3mm diameter) to inner ground layers. Failure to do so degrades θJA from 34°C/W to >60°C/W, risking thermal shutdown above 2.5W dissipation at 85°C ambient.
LTC3858IUH-2#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%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Phase 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-2#TRPBF FAQ
1.How can I place an order for LTC3858IUH-2#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3858IUH-2#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-2#TRPBF reliable?
The price and inventory of LTC3858IUH-2#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-2#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3858IUH-2#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3858IUH-2#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3858IUH-2#TRPBF?
LTC3858IUH-2#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3858IUH-2#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-2#TRPBF?
For technical support, including LTC3858IUH-2#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3858IUH-2#TRPBF requirements.
6.How does Aetrix verify that LTC3858IUH-2#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3858IUH-2#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-2#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3858IUH-2#TRPBF?
All LTC3858IUH-2#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3858IUH-2#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-2#TRPBF part is unused and in its original packaging.
Return procedure for LTC3858IUH-2#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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