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Analog Devices Inc. LTC3857EGN-1#PBF
- Part No.:
- LTC3857EGN-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3857EGN-1#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,926
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Product details
Overview
LTC3857EGN-1#PBF from Analog Devices (formerly Linear Technology) is a dual, 2-phase synchronous step-down controller IC designed for high-efficiency DC/DC conversion in space-constrained and low-quiescent-current applications. It delivers independent 3.3V/5A and 8.5V/3.5A outputs from a 4V–38V input, features 50μA no-load IQ, 0.8V reference accuracy (±12mV), and out-of-phase operation to reduce input ripple. It is used in automotive always-on systems and battery-powered digital devices.
For engineers reviewing the LTC3857EGN-1#PBF datasheet, LTC3857EGN-1#PBF pinout, LTC3857EGN-1#PBF application, or LTC3857EGN-1#PBF equivalent, key selection considerations include its dual-channel phase interleaving, RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation, programmable light-load modes (Burst/Pulse-Skipping/Continuous), and 28-pin SSOP package with verified thermal performance up to 125°C junction temperature.
Technical Context
The LTC3857EGN-1#PBF implements a constant-frequency current-mode architecture with two independent 180° out-of-phase controllers, each using an error amplifier (ITH1/ITH2), differential current sense comparator (SENSE1±/SENSE2±), and precision 0.8V feedback reference (VFB1/VFB2). Its PLLIN/MODE pin selects among Burst Mode®, pulse-skipping, or forced continuous conduction at light loads - directly affecting efficiency, output ripple, and EMI profile.
It integrates dual gate drivers (TG1/BG1 and TG2/BG2) with 2.5Ω pull-up / 1.5Ω pull-down on top-side and 2.4Ω/1.1Ω on bottom-side MOSFETs, supports external EXTVCC switchover (4.7V threshold), and includes dedicated TRACK/SS pins for soft-start or voltage tracking. The internal INTVCC LDO supplies 5.1V ±3% at up to 50mA from VIN or EXTVCC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide-range intermediate bus and battery chemistries including 12V/24V automotive and 5V–36V industrial rails. |
| Output Voltage Range | 0.8V to 24V - enables precise regulation of common logic rails (e.g., 3.3V, 5V, 8.5V) via external resistor dividers on VFB1/VFB2. |
| No-Load Quiescent Current | 50μA (one channel active) - extends battery life in always-on systems such as telematics and infotainment standby modes. |
| Switching Frequency Range | 75kHz–850kHz (phase-lockable) or 50kHz–900kHz (programmable) - allows optimization of inductor size vs. efficiency and EMI filtering requirements. |
| Reference Voltage Accuracy | 0.800V ±12mV (–40°C to 125°C) - ensures stable output regulation across automotive temperature extremes without external trimming. |
| Current Sense Threshold | 43mV to 57mV (typical 50mV) - sets peak inductor current limit; compatible with low-value RSENSE (e.g., 0.007Ω) or DCR sensing networks. |
| Duty Cycle Max | 99.4% - enables ultra-low dropout operation near VIN = VOUT, critical for high-voltage-to-low-voltage conversion (e.g., 12V→3.3V). |
Pinout & Package
Package: 28-lead plastic SSOP (GN), 5.6mm × 10.2mm, 0.635mm pitch, –40°C to +125°C operating junction temperature. Exposed pad not present; thermal resistance θJA = 90°C/W.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| ITH1, ITH2 | Error amplifier output / current limit control | Directly sets per-channel peak inductor current trip point; voltage range 0.425V–1.2V defines operating mode and load response. |
| VFB1, VFB2 | Feedback input | Compares output voltage (via resistive divider) to 0.8V reference; ±12mV accuracy ensures tight regulation under load/temperature variation. |
| SENSE1+, SENSE1− SENSE2+, SENSE2− |
Differential current sense inputs | Supports RSENSE or DCR sensing; common-mode range up to 28V enables high-side sensing in buck converters with elevated input rails. |
| PLLIN/MODE | Light-load mode select / sync input | GND = Burst Mode® (max efficiency), INTVCC = forced continuous (low ripple), external clock = phase-locked operation (EMI reduction). |
| FREQ | Frequency programming | Resistor-to-GND sets frequency 50kHz–900kHz; tied to GND = 350kHz, tied to INTVCC = 535kHz - enables layout-driven noise/size trade-offs. |
| TRACK/SS1, TRACK/SS2 | Soft-start / tracking control | Internal 1μA pull-up charges external capacitor for linear ramp; also accepts external voltage divider for coordinated power-up sequencing. |
| TG1, TG2 BG1, BG2 |
Top/bottom N-MOSFET gate drivers | Drive synchronous rectifiers with 2.5Ω/1.5Ω (TG) and 2.4Ω/1.1Ω (BG) on-resistance; supports >5A per channel with fast 13–28ns transitions. |
| PGOOD1 | Power-good indicator | Open-drain output asserts low when VFB1 deviates >±10% from setpoint - enables system-level fault detection and sequencing control. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by optimizing loop stability with standard ceramic capacitors - reduces BOM count and board area. |
| Out-of-Phase Dual Control | 180° interleaving cuts input RMS current by ~30%, reducing required input bulk capacitance and lowering conducted EMI at fundamental switching frequency. |
| Programmable Light-Load Modes | Selectable Burst Mode® (50μA IQ), pulse-skipping (low ripple + moderate IQ), or forced continuous (lowest ripple, higher IQ) - matches efficiency vs. noise requirements per application. |
| Independent Soft-Start & Tracking | Dedicated TRACK/SS1 and TRACK/SS2 pins enable staggered or synchronized startup of dual outputs - prevents inrush current stacking and supports FPGA/CPU core/I/O rail sequencing. |
| Robust Protection Suite | Includes output overvoltage protection (OVP), undervoltage lockout (UVLO), current foldback during short-circuit, and dropout detector with forced refresh for bootstrap capacitor recharge. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC Dual-Rail Converter |
|---|---|
|
Use Scenario: Powering 3.3V SoC core and 8.5V display backlight from 12V vehicle battery with cold-crank tolerance down to 4V. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent output rails with out-of-phase switching to minimize input capacitor stress and EMI. Use Value: 50μA quiescent current preserves battery during extended parking; 99.4% max duty cycle maintains regulation during cranking transients. |
Use Scenario: Generating isolated 3.3V logic and 8.5V analog sensor bias from 24V industrial bus in DIN-rail mounted controller. IC Role / Device Role / Timing Role: Dual-channel step-down controller with independent TRACK/SS pins enabling sequenced startup of digital and analog subsystems. Use Value: ±12mV reference accuracy ensures stable ADC reference and microcontroller operation across –40°C to +85°C ambient. |
| Battery-Powered Test Equipment | Distributed Telecom DC System |
|
Use Scenario: Portable oscilloscope requiring low-noise 3.3V digital rail and clean 8.5V analog front-end supply from Li-ion pack (3.0–4.2V/cell × 3). IC Role / Device Role / Timing Role: High-efficiency dual controller with selectable pulse-skipping mode to balance ripple-sensitive analog performance and battery runtime. Use Value: Pulse-skipping mode delivers <10mVpp ripple at light loads while maintaining >85% efficiency at 100mA - superior to forced CCM in portable use. |
Use Scenario: Intermediate bus converter in 48V telecom shelf supplying 3.3V FPGA banks and 8.5V RF amplifiers with strict thermal limits. IC Role / Device Role / Timing Role: Phase-interleaved controller driving paralleled MOSFETs per phase to distribute heat and reduce thermal hotspots on PCB. Use Value: 28-pin SSOP package with 90°C/W θJA enables convection-cooled operation at full 5A/3.5A load without heatsink - lowers system cost. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3857IGN-1#PBF | Same die, automotive-grade (–40°C to +125°C guaranteed over full temp range); identical pinout, specs, and package. | Required for AEC-Q100-compliant automotive designs where extended temperature validation is mandated. | Select LTC3857IGN-1#PBF when full production testing across –40°C to +125°C is contractually required. |
| MP2918GL-Z | Single-chip dual controller with integrated MOSFET drivers only; lacks EXTVCC support, PLL sync, and TRACK/SS flexibility; 40μA IQ but fixed 600kHz fSW. | Suitable for cost-sensitive, fixed-frequency applications where board space is critical but advanced sequencing and efficiency tuning are unnecessary. | Choose MP2918GL-Z only if design tolerates fixed frequency, no external sync, and no soft-start customization. |
Compared with LTC3857EGN-1#PBF, the LTC3857IGN-1#PBF offers identical functionality with enhanced temperature assurance, while the MP2918GL-Z trades configurability and thermal robustness for integration density and lower unit cost - making it viable only in thermally benign, non-automotive contexts.
Availability
LTC3857EGN-1#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLCs, battery-powered test equipment, and distributed telecom DC systems requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across temperature.
Supply support for LTC3857EGN-1#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, serving aerospace, automotive, industrial, and communications markets.
The LTC3857-1 product line delivers dual-phase synchronous buck controllers optimized for high efficiency, low IQ, and flexible sequencing in harsh environments - targeting automotive always-on, battery-operated, and distributed power architectures.
FAQ
What is the maximum junction temperature specification for the LTC3857EGN-1#PBF?
The LTC3857EGN-1#PBF has a maximum junction temperature (TJMAX) of 125°C, with guaranteed operation from –40°C to +125°C. Its thermal resistance θJA is 90°C/W in the 28-lead SSOP package. To maintain reliability, ensure PCB copper area and airflow keep actual TJ ≤ 125°C under worst-case load and ambient conditions. The LTC3857EGN-1#PBF datasheet provides derating curves for power dissipation vs. ambient temperature.
Does the LTC3857EGN-1#PBF support external synchronization of both channels?
Yes, the LTC3857EGN-1#PBF supports external synchronization via the PLLIN/MODE pin. When an external clock signal is applied to this pin, the internal phase-locked loop synchronizes the rising edge of TG1 to the external clock's rising edge, and the second channel (TG2) remains 180° out of phase. This feature reduces beat frequencies and simplifies EMI filter design in multi-converter systems. The LTC3857EGN-1#PBF does not require additional components for sync - only a clean CMOS/TTL clock source referenced to SGND.
How does the LTC3857EGN-1#PBF implement output voltage tracking during startup?
The LTC3857EGN-1#PBF uses dedicated TRACK/SS1 and TRACK/SS2 pins to enable precise output voltage tracking. Each pin features an internal 1μA pull-up current source. Connecting an external resistor divider from a master supply to SGND on TRACK/SS1 or TRACK/SS2 causes the corresponding VOUT to follow that voltage during startup. Alternatively, a capacitor to SGND creates a linear soft-start ramp. This ensures controlled, glitch-free power-up of FPGAs, processors, or mixed-signal ICs. The LTC3857EGN-1#PBF regulates VFB to the smaller of 0.8V or the TRACK/SS voltage - guaranteeing monotonic rise.
Can the LTC3857EGN-1#PBF operate with only one channel enabled?
Yes, the LTC3857EGN-1#PBF supports independent channel control via RUN1 and RUN2 pins. Pulling RUN1 below 1.26V disables Channel 1 while Channel 2 remains fully operational, and vice versa. Pulling both RUN1 and RUN2 below 0.7V places the entire LTC3857EGN-1#PBF into shutdown mode, reducing quiescent current to <8μA. This capability enables dynamic power scaling in systems with variable load profiles - for example, disabling the 8.5V rail when display is off while maintaining 3.3V for MCU sleep retention.
What current sensing methods does the LTC3857EGN-1#PBF support?
The LTC3857EGN-1#PBF supports both RSENSE (shunt resistor) and DCR (inductor winding resistance) current sensing via differential SENSE1± and SENSE2± inputs. Each pair accepts common-mode voltages up to 28V, enabling high-side sensing configurations. The current sense threshold is factory-trimmed to 50mV (43–57mV), allowing accurate peak-current-mode control with minimal power loss. For DCR sensing, external RC networks compensate for inductor thermal drift. The LTC3857EGN-1#PBF does not require additional op-amps or gain stages - all signal conditioning is internal.
LTC3857EGN-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 28-SSOP (0.154", 3.90mm Width)
- 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:
- Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SSOP
LTC3857EGN-1#PBF FAQ
1.How can I place an order for LTC3857EGN-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3857EGN-1#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 LTC3857EGN-1#PBF reliable?
The price and inventory of LTC3857EGN-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3857EGN-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3857EGN-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3857EGN-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3857EGN-1#PBF?
LTC3857EGN-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3857EGN-1#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 LTC3857EGN-1#PBF?
For technical support, including LTC3857EGN-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3857EGN-1#PBF requirements.
6.How does Aetrix verify that LTC3857EGN-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3857EGN-1#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 LTC3857EGN-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3857EGN-1#PBF?
All LTC3857EGN-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3857EGN-1#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 LTC3857EGN-1#PBF part is unused and in its original packaging.
Return procedure for LTC3857EGN-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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