LTC3858

PRODUCTION

Low I_Q, Dual 2-Phase Synchronous Step-Down Controller

Part Models: 4
1ku List Price: Starting From $4.78

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Overview

Low Operating I_Q: 170μA (One Channel On)
Wide Output Voltage Range: 0.8V ≤ V_OUT ≤ 24V
Wide V_IN Range: 4V to 38V
R_SENSE or DCR Current Sensing
Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
OPTI-LOOP^® Compensation Minimizes C_OUT
Phase-Lockable Frequency (75kHz-850kHz)
Programmable Fixed Frequency (50kHz-900kHz)
Selectable Continuous, Pulse-Skipping or Burst Mode^® Operation at Light Loads

Very Low Dropout Operation: 99% Duty Cycle
Adjustable Output Voltage Soft-Start
Power Good Output Voltage Monitor
Output Overvoltage Protection
Output Latch-Off Protection During Short Circuit
Low Shutdown I_Q: 8μA
Internal LDO Powers Gate Drive from V_IN or EXTV_CC
No Current Foldback During Start-Up
Small 5mm × 5mm QFN Package

The LTC3858 is a high performance dual step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows a phase-lockable frequency of up to 850kHz. Power loss and noise due to the input capacitor ESR are minimized by operating the two controller outputs out of phase.

The 170μA no-load quiescent current extends operating life in battery-powered systems. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3858 features a precision 0.8V reference and a power good output indicator. A wide 4V to 38V input supply range encompasses a wide range of intermediate bus voltages and battery chemistries.

Independent soft-start pins for each controller ramp the output voltages during start-up. The output latch-off feature protects the circuit in short-circuit conditions.

For a leaded 28-lead SSOP package with a fixed current limit and one PGOOD output, without phase modulation or a clock output, see the LTC3858-1 data sheet.


	LTC3858	LTC3858-1	LTC3858-2
Features	Adjustable Current Limit, Clock Output, Phase Modulation, 2 PGOOD Outputs	Fixed Current Limit, One PGOOD Output	Overvoltage protection crowbar and short-circuit latchoff disabled
Package	QFN-32	SSOP-28	QFN-32

Applications

Automotive Systems
Battery Operated Digital Devices
Distributed DC Power Systems

Part Models: 4
1ku List Price: Starting From $4.78

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LTC3858EUH#PBF	32-Lead QFN (5mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3858EUH#TRPBF	32-Lead QFN (5mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3858IUH#PBF	32-Lead QFN (5mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3858IUH#TRPBF	32-Lead QFN (5mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Jan 20, 2022 - 21_0269 Addition of Alternate Assembly Site ASE Taiwan for Select LFCSP Products
		PCN21_0269_Form Material_Report Detailed Change Description Qualification Results Summary
LTC3858EUH#PBF	PRODUCTION
LTC3858EUH#TRPBF	PRODUCTION
LTC3858IUH#PBF	PRODUCTION
LTC3858IUH#TRPBF	PRODUCTION
Jul 31, 2020 - 20_0245 Notification of Wafer Fab Location Change for 0.6µm BICMOS Process Devices from ADI Milpitas (Hillview) to Vanguard Int. (Taiwan)
		PCN20_0245_Form Material_Report Delta Qualification Matrix Other Qualification Results Summary
LTC3858EUH#PBF	PRODUCTION
LTC3858EUH#TRPBF	PRODUCTION
LTC3858IUH#PBF	PRODUCTION
LTC3858IUH#TRPBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Circuit Monitors 1
LTC2960	RECOMMENDED FOR NEW DESIGNS	36V Nano-Current Two-Input Voltage Monitor
Protection Switches & Controllers 2
LTC2955	RECOMMENDED FOR NEW DESIGNS	Pushbutton On/Off Controller with Automatic Turn-On
LT4363	RECOMMENDED FOR NEW DESIGNS	High Voltage Surge Stopper with Current Limit
Switching Regulators & Controllers 1
LTC3880	RECOMMENDED FOR NEW DESIGNS	Dual Output PolyPhase Step-Down DC/DC Controller with Digital Power System Management

Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

LTC3858
LTC3858-1
LTC3858-2

LTpowerCAD 4

Design tools for the following parts are available in LTpowerCAD:

LTC3858
LTC3858-1
LTC3858-2

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

LTpowerCAD^® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.

Evaluation Kits

LTC3858EUH Demo Board | 4-Phase Solution, 16V ≤ VIN ≤ 26V, VOUT = 12V @ 50A

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Product Details

Demonstration circuit 1510A is a high output voltage, high efficiency synchronous poly-phase buck converter featuring the LTC3858EUH. The demo circuit is available in two versions. The input voltage of both versions is 16V to 26V. DC1510A-A is configured using 2 LTC3858's with 4 phase interleaving operation which provides a 12V/50A output, while the DC1510A-B is configured with 1 LTC3858 with 2 phase inter-leaving operation which provides a 12V/25A output.

Resources

DC1510A - Demo Manual
8/26/2010

DC1510A - Design Files
8/26/2010

DC1510A-A - Schematic
8/26/2010

LTC3858IUH Demo Board | 4.5V ≤ VIN ≤ 36V, VOUT1 = 3.3V @ 5A, VOUT2 = 8.5V @ 3A

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Product Details

Demonstration circuit 1381A is a Low Quiescent Current, Dual Output Synchronous Buck Converter featuring the LTC3857EUH/LTC3858EUH. The DC1381A provides 3.3V/5A and 8.5V/3A from a wide input voltage range of 4.5V to 36V, making it suitable for automotive or other battery fed application where low quiescent current is important.

Two versions of the board are available. DC-1381A-A is for the LTC3857EUH, while the DC1381A-B is for the LTC3858EUH. The LTC3857EUH offers lower quiescent current and smaller burst mode ripple, while the LTC3858EUH offers latch-off protection and increased burst mode efficiency.