Features

• Wide Input Range: 3.5V to 25V
• Three Switching Regulators with Internal Power Switches: 3A Step-Down, 2A Step-Down, 1.5A Inverting/Boost
• Antiphase Switching Reduces Ripple
• Independent Shutdown/Soft-Start Pins
• Independent Power Good Indicators Ease Supply Sequencing
• Input Voltage Power Good Indicators Monitor Input Supply
• Uses Small Inductors and Ceramic Capacitors
• Constant 1.1MHz Switching Frequency
• Thermally Enhanced 28-Lead TSSOP Package

Typical Application

Description

The LT1941 is a triple current mode DC/DC converter with internal power switches. Two of the regulators are step-down converters with 3A and 2A power switches. The third regulator can be configured as a boost, inverter or SEPIC converter and has a 1.5A power switch. All three converters are synchronized to a 1.1MHz oscillator. The two step-down converters run with opposite phase, reducing input ripple current. The output voltages are set with external resistor dividers and each regulator has independent shutdown and soft-start circuits. Each regulator generates a power good signal when its output is in regulation, easing power supply sequencing and interfacing with microcontrollers and DSPs.

The high switching frequency offers several advantages by permitting the use of small inductors and ceramic capacitors, leading to a very small triple output solution. The constant switching frequency, combined with low impedance ceramic capacitors, result in low, predictable output ripple. With its wide input voltage range of 3.5V to 25V, the LT1941 regulates a broad array of power sources from 4-cell batteries and 5V logic rails to unregulated wall transformers, lead acid batteries and distributed-power supplies.