Product Summary

The LTC3857 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 ESR of the input capacitor ESR are minimized by operating the two controller output stages out of phase.

The 50μA no-load quiescent current extends operating run time in battery-powered systems. The LTC3857 features a precision 0.8V reference and power good output indicators. A wide 4V to 38V input supply range encompasses a wide range of intermediate bus voltages and battery chemistries.

Independent TRACK/SS pins for each controller ramp the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode at light loads.

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 LTC3857-1 data sheet.


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Features

Low Operating IQ: 50μA (One Channel On)
Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
Wide VIN Range: 4V to 38V (40V Abs Max)
RSENSE or 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 Low Ripple Burst Mode? Operation at Light Loads
Selectable Current Limit
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Output Voltage Soft-Start or Tracking
Power Good Output Voltage Monitors
Output Overvoltage Protection
Low Shutdown IQ : <8μA
Internal LDO Powers Gate Drive from VIN or EXTVCC
No Current Foldback During Start-up
5mm × 5mm QFN Package

Image Part No Mfg Description Data Sheet Download Pricing
(USD)
Quantity
LTC3857IGN-1#PBF
LTC3857IGN-1#PBF


IC REG CTRLR BUCK PWM CM 28-SSOP

Data Sheet

0-147: $3.47
Image Part No Mfg Description Data Sheet Download Pricing
(USD)
Quantity
LTC3025
LTC3025

Other


Data Sheet

Negotiable 
LTC3025EDC#TR
LTC3025EDC#TR


IC REG LDO ADJ .3A 6DFN

Data Sheet

0-5000: $0.88
LTC3025EDC#TRM
LTC3025EDC#TRM


IC REG LDO ADJ .3A 6DFN

Data Sheet

0-5000: $0.88
LTC3025EDC#TRMPBF
LTC3025EDC#TRMPBF


IC REG LDO ADJ .3A 6DFN

Data Sheet

0-1000: $0.88
LTC3025EDC#TRPBF
LTC3025EDC#TRPBF


IC REG LDO ADJ .3A 6DFN

Data Sheet

0-2500: $0.88
LTC3025EDC-1#TRMPBF
LTC3025EDC-1#TRMPBF


IC REG LDO ADJ .5A 6DFN

Data Sheet

0-1000: $0.97