LTC3868 - Low IQ, Dual 2-Phase Synchronous 2-Phase Synchronous Step-Down Controller
· Low Operating IQ: 170μA (One Channel On)
· Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 14V
· Wide VIN Range: 4V to 24V
· 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 to 850kHz)
· Programmable Fixed Frequency (50kHz to 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 Latchoff Protection During Short Circuit
· Low Shutdown IQ: 8μA
· Internal LDO Powers Gate Drive from VIN or EXTVCC
· No Current Foldback During Start-Up
· Small
Typical Application
Description
The LTC3868 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 LTC3868 features a precision 0.8V reference and a power good output indicator. A wide 4V to 24V 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. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The output short-circuit latchoff feature further 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 LTC3868-1 data sheet
Packaging
QFN-24
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