Dual, 2-Phase Step-Down Controller with Tracking

The LTC3828 is a dual high performance step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows for a phase-lockable frequency of up to 550kHz. The TRCKSS pin provides both soft-start and tracking functions. Multiple LTC3828s can be daisy-chained in applications requiring more than two voltages to be tracked.

OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The precision 0.8V reference and power good output indicator are compatible with a wide 4.5V to 28V (30V maximum) input supply range, encompassing all battery chemistries.

The RUN pins control their respective channels independently. The FCB/PLLIN pin selects among Burst Mode® operation, skip-cycle mode and continuous current mode. Current foldback limits MOSFET dissipation during short-circuit conditions. Reverse current and current foldback functions are disabled during soft-start.

Applications

* Telecom Infrastructure

* ASIC Power Supply

* Industry Equipment

* Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise

* Tracking for Both Outputs

* Constant Frequency Current Mode Control

* Wide VIN Range: 4.5V to 28V Operation

* Power Good Output Voltage Indicator

* Adjustable Soft-Start Current Ramping

* Foldback Output Current Limiting-Disabled at Start-Up

* No Reverse Current During Soft-Start Interval

* Clock Output for 3-, 4-, 6-Phase Operation

* Dual N-Channel MOSFET Synchronous Drive

* ±1% Output Voltage Accuracy

* Phase-Lockable Fixed Frequency 260kHz to 550kHz

* OPTI-LOOP® Compensation Minimizes COUT

* Very Low Dropout Operation: 99% Duty Cycle

* Output Overvoltage Protection

* Small 28-Lead SSOP and 5mm × 5mm QFN Packages