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Analog Devices Inc. LTC3857EUH#PBF
- Part No.:
- LTC3857EUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3857EUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:146
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Product details
Overview
LTC3857EUH#PBF from Analog Devices (formerly Linear Technology) is a dual, 2-phase synchronous step-down controller IC driving two independent N-channel MOSFET stages for high-efficiency DC/DC conversion. It delivers 5A at 3.3V and 3.5A at 8.5V with 50μA no-load quiescent current, 0.8V reference accuracy, and out-of-phase operation to reduce input ripple-ideal for automotive always-on systems and battery-powered digital devices.
For engineers reviewing the LTC3857EUH#PBF datasheet, LTC3857EUH#PBF pinout, LTC3857EUH#PBF application, or LTC3857EUH#PBF equivalent, key selection criteria include dual-channel phase control, RSENSE/DCR current sensing, OPTI-LOOP® compensation, programmable light-load modes (Burst/Pulse-Skipping/Continuous), and 4V–38V input range with 99% duty cycle capability.
Technical Context
The LTC3857EUH#PBF implements a constant-frequency current-mode architecture with two independent controllers operating 180° out of phase to minimize input capacitor ESR stress and power supply noise. Each channel features a transconductance error amplifier (gm = 2 mmho), precision 0.8V feedback reference (±12 mV over temperature), and selectable current limit via ILIM pin (22/43/64 mV thresholds).
It integrates dual gate drivers (TG/BG) with 2.5Ω pull-up / 1.5Ω pull-down on TG and 2.4Ω/1.1Ω on BG, supports external clock synchronization (75–850 kHz), and provides independent TRACK/SS pins for soft-start or voltage tracking-enabling coordinated sequencing in multi-rail systems without external circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 38V (40V absolute max); supports wide-input industrial and automotive battery buses. |
| VOUT Range | 0.8V to 24V per channel; enables precise regulation of logic, I/O, and analog rails. |
| IQ (One Channel On) | 50μA in Sleep Mode; extends runtime in battery-operated systems with low-power wake-up capability. |
| Quiescent Shutdown IQ | <8μA; enables ultra-low-power system standby with full rail disable. |
| Frequency Range | 75kHz–850kHz PLL-sync or 50kHz–900kHz programmable; allows EMI optimization and size/cost trade-offs. |
| Duty Cycle Max | 99.4%; supports high-step-down ratios and dropout operation near VIN ≈ VOUT. |
| Current Sense | RSENSE or DCR sensing; eliminates sense resistor loss while maintaining accurate overcurrent protection. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed thermal pad (Pin 33 = SGND), rated for –40°C to 125°C junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1– / SENSE2– (1, 9) | Differential current comparator (–) input | Supplies bias current when > INTVCC – 0.5V; enables accurate DCR/RSENSE sensing with common-mode rejection. |
| TG1 / TG2 (26, 15) | Top N-MOSFET gate drive output | Floating driver with INTVCC-referenced swing; requires bootstrap capacitor for high-side switching. |
| BG1 / BG2 (23, 18) | Bottom N-MOSFET gate drive output | Ground-referenced driver; complements TG to enable synchronous rectification and high efficiency. |
| TRACK/SS1 / TRACK/SS2 (29, 13) | Soft-start and voltage tracking input | Internal 1μA pull-up enables linear ramp via external capacitor; supports rail sequencing with external supply divider. |
| PLLIN/MODE (5) | Light-load mode select & sync input | Selects Burst Mode (GND), Pulse-Skipping (1.2V–INTVCC–1.3V), or Continuous (INTVCC); also accepts external clock for phase-locking. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by optimizing loop stability across load and line variations-reducing BOM cost and board area. |
| Out-of-Phase Dual Control | Reduces RMS input current ripple by ~70% vs. in-phase operation, enabling smaller input capacitors and lower EMI filter requirements. |
| Programmable Light-Load Modes | Three selectable modes (Burst/Pulse-Skipping/Continuous) allow optimization of efficiency vs. output ripple/noise for each application condition. |
| Independent Current Limit Selection | ILIM pin configures max sense threshold to 22/43/64 mV-enabling precise overcurrent protection matching MOSFET RDS(on) and layout parasitics. |
| Power Good Monitoring | PGOOD1/PGOOD2 open-drain outputs provide independent rail-status indication with ±10% trip hysteresis-critical for system sequencing and fault reporting. |
Applications
| Automotive Always-On Systems | Battery-Powered Digital Devices |
|---|---|
Use Scenario: Powering infotainment, ADAS sensors, and telematics modules from 12V vehicle battery with <100μA standby draw. IC Role / Device Role / Timing Role: Dual-channel controller managing 3.3V microcontroller core and 8.5V display backlight rails with independent soft-start and tracking. Use Value: 50μA quiescent current extends battery life during ignition-off periods; out-of-phase operation suppresses conducted EMI in sensitive RF environments. | Use Scenario: Supplying FPGA I/O banks and memory interfaces in portable test equipment powered by Li-ion battery pack. IC Role / Device Role / Timing Role: High-efficiency dual buck controller delivering regulated 3.3V and 8.5V from 9–38V input, with Burst Mode extending runtime at light loads. Use Value: 99% duty cycle enables operation down to 3.5V input; RSENSE/DCR sensing eliminates sense resistor losses critical for thermal management. |
| Distributed DC Power Systems | Industrial Embedded Controllers |
Use Scenario: Intermediate bus converter in 48V telecom or server rack supplying multiple point-of-load regulators. IC Role / Device Role / Timing Role: Dual-phase controller generating stable 12V and 5V intermediate rails with phase-lock capability for system-wide clock synchronization. Use Value: 850kHz sync range allows tight frequency alignment across multiple LTC3857 units; EXTVCC input enables efficient self-bias from downstream rails. | Use Scenario: Powering ARM-based PLC CPU, CAN transceiver, and isolated I/O modules in factory automation hardware. IC Role / Device Role / Timing Role: Dual controller providing 3.3V logic rail and 8.5V analog sensor supply with independent PGOOD monitoring and overvoltage protection. Use Value: 0.8V reference accuracy (±12 mV) ensures reliable ADC reference stability; output overvoltage protection prevents damage to connected peripherals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual synchronous step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3857-1EUH#PBF | Fixed current limit, single PGOOD output, no phase modulation or CLKOUT; leaded SSOP package. | Suitable for cost-sensitive, non-synchronized designs where dual-phase coordination and clock daisy-chaining are unnecessary. | Select when simplified configuration and legacy SSOP footprint are prioritized over flexibility and advanced timing control. |
| MP2918GL-Z | Single-chip dual controller with integrated MOSFET drivers; 4.5–36V input; fixed 300kHz/600kHz frequencies; no PLL sync or programmable light-load modes. | Targeted at space-constrained consumer electronics where integration reduces component count but sacrifices frequency agility and low-IQ optimization. | Select when board area is critical and 50μA IQ or 75–850kHz sync range are not required. |
Compared with LTC3857EUH#PBF, the LTC3857-1EUH#PBF trades phase control and clock output for lower cost and simpler layout, while MP2918GL-Z offers higher integration at the expense of design flexibility and ultra-low quiescent current-making LTC3857EUH#PBF optimal for high-performance, thermally constrained, or EMI-sensitive dual-rail systems.
Availability
LTC3857EUH#PBF is available at Aetrix Electronics and suitable for automotive always-on systems, battery-powered digital devices, and distributed DC power systems requiring stable component supply, long-lifecycle support, and guaranteed parametric performance across –40°C to 125°C.
Supply support for LTC3857EUH#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. (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC3857EUH#PBF belongs to ADI's Power by Linear™ controller family, designed specifically for high-efficiency, low-quiescent-current, multi-phase DC/DC conversion in automotive, industrial, and portable applications demanding reliability and precision.
FAQ
What is the minimum input voltage supported by the LTC3857EUH#PBF?
The LTC3857EUH#PBF supports a minimum input voltage of 4V, verified across its full operating junction temperature range (–40°C to 125°C). This enables compatibility with partially discharged 12V lead-acid batteries and regulated 5V intermediate buses. Operation below 4V triggers undervoltage lockout (UVLO), which disables switching until INTVCC rises above 3.8V (typical) during power-up.
How does the LTC3857EUH#PBF achieve 50μA quiescent current?
The LTC3857EUH#PBF achieves 50μA quiescent current in Sleep Mode (one channel active) through selective circuit disabling-including shutdown of gate drivers, oscillator, and error amplifier bias-while retaining critical functions like reference generation and RUN pin monitoring. This low-IQ state is confirmed in the Electrical Characteristics table (IQ = 50μA typ, 75μA max) and validated in Figure G17 (Quiescent Current vs Temperature).
Can the LTC3857EUH#PBF synchronize to an external clock source?
Yes, the LTC3857EUH#PBF can synchronize to an external clock via the PLLIN/MODE pin, supporting a 75kHz–850kHz input frequency range with phase alignment to the rising edge of the external signal. This capability is explicitly specified in the Electrical Characteristics table under "fSYNC" and confirmed in the PIN FUNCTIONS description for PLLIN/MODE (Pin 5).
What package type and thermal characteristics does the LTC3857EUH#PBF use?
The LTC3857EUH#PBF uses a 32-lead 5mm × 5mm plastic QFN package (UH) with exposed thermal pad (Pin 33 = SGND), rated for –40°C to 125°C junction temperature. Its thermal resistance is θJA = 34°C/W, and the exposed pad must be soldered to PCB copper for rated performance-details confirmed in the ABSOLUTE MAXIMUM RATINGS section and ORDER INFORMATION table.
Does the LTC3857EUH#PBF support both RSENSE and DCR current sensing?
Yes, the LTC3857EUH#PBF supports both RSENSE and DCR current sensing, as stated in the FEATURES list and detailed in the PIN FUNCTIONS section: SENSE1+/SENSE2+ (Pins 32/10) connect to resistive shunts or DCR networks, and the differential comparator inputs (SENSE1–/SENSE2–) accommodate the associated common-mode voltages. This dual-sensing flexibility is confirmed in the Applications Information and Functional Diagram.
LTC3857EUH#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 32-WFQFN Exposed Pad
- Packaging:
- Tube
- 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, Phase Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
LTC3857EUH#PBF FAQ
1.How can I place an order for LTC3857EUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3857EUH#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 LTC3857EUH#PBF reliable?
The price and inventory of LTC3857EUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3857EUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3857EUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3857EUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3857EUH#PBF?
LTC3857EUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3857EUH#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 LTC3857EUH#PBF?
For technical support, including LTC3857EUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3857EUH#PBF requirements.
6.How does Aetrix verify that LTC3857EUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3857EUH#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 LTC3857EUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3857EUH#PBF?
All LTC3857EUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3857EUH#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 LTC3857EUH#PBF part is unused and in its original packaging.
Return procedure for LTC3857EUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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