Dual 60V Monolithic 1A Step-Down Switching Regulator

The LT3988 is a dual, current mode, step-down, DC/DC converter that accepts two input voltages up to 60V (80V transient), which may be driven from separate supplies or can be cascaded. High efficiency switches are included on the die along with internal boost diodes and loop compensation. Both converters are capable of generating 1A outputs, are synchronized to a single oscillator programmable up to 2.5MHz, and run with opposite phases, reducing input ripple current.

The switching frequency is set with a single resistor yielding a range of 250kHz to 2.5MHz, or a clock signal can be applied to the SYNC pin. The LT3988’s high switching frequency allows the use of small inductors and capacitors, resulting in a very small dual output supply. The constant switching frequency, combined with low impedance ceramic capacitors, results in low, predictable output ripple. A current mode PWM architecture provides fast transient response with cycle-by-cycle current limiting. Diode current sense and thermal shutdown provide additional protection.

The LT3988 is available in a 16-lead MSOP package with an exposed pad for low thermal resistance.

Applications

* Commercial Vehicle Battery Regulation

* Industrial Supplies

* Distributed Supply Regulation

* Wide Input Range:

* Operation from 4.1V to 60V

* Overvoltage Lockout Protects Circuit Through 80V Transients

* Two 1A Output Switching Regulators with Internal Power Switches

* Short Circuit Robust

* Adjustable 250kHz to 2.5MHz Switching Frequency, Synchronizable Over the Full Range

* Integrated Boost Diodes

* Integrated Loop Compensation

* Anti-Phase Switching Reduces Ripple

* Low Shutdown IQ (<2μA)

* Uses Small Inductors and Ceramic Capacitors

* Thermally Enhanced, 16-Lead MSOP Package