Features

• Low Ripple Burst Mode® Operation:
  7μA I_Q at 12V_IN to 5V_OUT
  Output Ripple (<10mV Typ.)
• Dual Supply Pins:
  Improves Efficiency
  Reduces Minimum Supply Voltage to ~1V after
  Start-Up to Extend Battery Life
• Wide Input Voltage Range of ~1V to 60V (2.5V to 32V for Start-Up)
• PG Functional for Input Supply Down to 1.3V
• FMEA Fault Tolerant in TSSOP Package
• Fixed Frequency PWM, SEPIC/BOOST/FLYBACK Topologies
• NPN Power Switch: 2A/70V
• Programmable Switching Frequency: 250kHz to 1.5MHz
• UVLO Programmable on SWEN Pin
• Soft-Start Programmable with One Capacitor
• Small 20-Lead QFN or 20-Lead TSSOP Packages

Typical Application

Description

The LT®8494 is an adjustable frequency (250kHz to 1.5MHz) monolithic switching regulator. Quiescent current can be less than 7μA when operating and is ~0.3μA when SWEN is low. The LT8494 can be configured as either a SEPIC, boost or flyback converter.

The low ripple Burst Mode operation maintains high efficiency at low output current while keeping output ripple below 10mV. Dual supply pins (V_IN and BIAS) allow the part to automatically operate from the most efficient supply. Input supply voltage can be up to 60V for SEPIC topologies and up to 32V (with ride-through up to 60V) for boost and flyback topologies. After start-up, battery life is extended since the part can draw current from its output (BIAS) even when V_IN voltage drops below 2.5V.

Using a resistor divider on the SWEN pin provides a programmable undervoltage lockout (UVLO) for the converter. A power good flag signals when V_OUT reaches 92% of the programmed output voltage.

Additional features such as frequency foldback and softstart are integrated. The LT8494 is available in 20-lead QFN and 20-lead TSSOP packages with exposed pads for low thermal resistance. Fault tolerance in the TSSOP allows for adjacent pin shorts or an open without raising the output voltage above its programmed value.