LTC3858-1 Series

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

Catalog

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

Part	Output Type	Output Configuration	Number of Outputs	Frequency - Switching [Max]	Frequency - Switching [Min]	Function	Output Phases	Control Features	Topology	Duty Cycle (Max) [Max]	Voltage - Supply (Vcc/Vdd) [Max]	Voltage - Supply (Vcc/Vdd) [Min]	Mounting Type	Package / Case	Operating Temperature [Min]	Operating Temperature [Max]	Supplier Device Package
Analog Devices LTC3858IGN-1#TRPBF	Transistor Driver	Positive	2	535 kHz 835 kHz	105 kHz 350 kHz	Step-Down	2	Enable Frequency Control Power Good Soft Start	Buck	99.4 %	38 V	4 V	Surface Mount	28-SSOP	-40 °C	125 ¯C	28-SSOP
Analog Devices LTC3858IUH#PBF	Transistor Driver	Positive	2	535 kHz 835 kHz	105 kHz 350 kHz	Step-Down	2	Current Limit Enable Frequency Control Power Good Soft Start	Buck	99.4 %	38 V	4 V	Surface Mount		-40 °C	125 ¯C	32-QFN (5x5)
Analog Devices LTC3858IUH#TRPBF	Transistor Driver	Positive	2	535 kHz 835 kHz	105 kHz 350 kHz	Step-Down	2	Current Limit Enable Frequency Control Power Good Soft Start	Buck	99.4 %	38 V	4 V	Surface Mount		-40 °C	125 ¯C	32-QFN (5x5)
Analog Devices LTC3858EUFD-1#PBF	Transistor Driver	Positive	2	535 kHz 835 kHz	105 kHz 350 kHz	Step-Down	2	Enable Frequency Control Power Good Soft Start	Buck	99.4 %	38 V	4 V	Surface Mount	28-WFQFN Exposed Pad	-40 °C	125 ¯C	28-QFN (4x5)
Analog Devices LTC3858IUH-2#TRPBF	Transistor Driver	Positive	2	535 kHz 835 kHz	105 kHz 350 kHz	Step-Down	2	Current Limit Enable Frequency Control Phase Control Power Good Soft Start	Buck	99 %	38 V	4 V	Surface Mount		-40 °C	125 ¯C	32-QFN (5x5)
Analog Devices LTC3858EUFD-1#TRPBF	Transistor Driver	Positive	2	535 kHz 835 kHz	105 kHz 350 kHz	Step-Down	2	Enable Frequency Control Power Good Soft Start	Buck	99.4 %	38 V	4 V	Surface Mount	28-WFQFN Exposed Pad	-40 °C	125 ¯C	28-QFN (4x5)

Catalog

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

Key Features

• Low Operating IQ: 170μA (One Channel On)

• Wide Output Voltage Range: 0.8V ≤ VOUT≤ 24V

• Wide VINRange: 4V to 38V

• RSENSEor DCR Current Sensing

• Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise

• OPTI-LOOP®Compensation Minimizes COUT

• 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 IQ: 8μA

• Internal LDO Powers Gate Drive from VINor EXTVCC

• No Current Foldback During Start-Up

• Tiny 4mm × 5mm QFN and Narrow SSOP Packages

Description

The LTC3858-1 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 LTC3858-1 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 leadless 32-pin QFN package with the additional features of adjustable current limit, clock out, phase modulation and two PGOOD outputs, see the LTC3858 data sheet.LTC3858LTC3858-1LTC3858-2FeaturesAdjustable Current Limit, Clock Output, Phase Modulation, 2 PGOOD OutputsFixed Current Limit, One PGOOD OutputOvervoltage protection crowbar and short-circuit latchoff disabledPackageQFN-32SSOP-28QFN-32ApplicationsAutomotive SystemsBattery Operated Digital DevicesDistributed DC Power Systems