Features

• Low Ripple Burst Mode® Operation
  2.5μA I_Q at 12V_IN to 3.3V_OUT
  Output Ripple < 5mV_P-P
• Wide Input Voltage Range: 4.2V to 62V Operating
• Adjustable Switching Frequency: 200kHz to 2.2MHz
• Integrated Boost and Catch Diodes
• 350mA Output Current
• Fixed Output Voltages: 3.3V, 5V
  2μA IQ at 12V_IN
• Accurate Programmable Undervoltage Lockout
• FMEA Fault Tolerant (MSOP Package)
  Output Stays at or Below Regulation Voltage During
  Adjacent Pin Short or When a Pin is Left Floating
• Low Shutdown Current: I_Q = 0.7μA
• Internal Sense Limits Catch Diode Current
• Power Good Flag
• Small, Thermally Enhanced 16-Pin MSOP and (3mm × 3mm) DFN Packages

Typical Application

Description

The LT®3990 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 62V, and consumes only 2.5μA of quiescent current. A high efficiency switch is included on the die along with the catch diode, boost diode, and the necessary oscillator, control and logic circuitry. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 5mV in a typical application. Current mode topology is used for fast transient response and good loop stability. A catch diode current limit provides protection against shorted outputs and overvoltage conditions. An accurate programmable undervoltage lockout feature is available, producing a low shutdown current of 0.7μA. A power good flag signals when V_OUT reaches 90% of the programmed output voltage. The LT3990 is available in small, thermally enhanced 16-pin MSOP and 3mm × 3mm DFN packages.