Summary of LT8494 – SEPIC/Boost DC/DC Converter with 2A, 70V Switch, and 7μA Quiescent Current
The LT8494 is a monolithic switching regulator offering low quiescent current (7μA) and adjustable frequency (250kHz–1.5MHz). It supports SEPIC, boost, and flyback topologies with a wide input range up to 60V. Features include dual supply pins for efficiency, Burst Mode operation for low ripple (<10mV), programmable UVLO, soft-start, and fault tolerance in TSSOP packages.
Parts used in the LT8494 Project:
- LT8494 Monolithic Switching Regulator
- NPN Power Switch (2A/70V)
- Resistor Divider (for SWEN pin UVLO)
- Single Capacitor (for Soft-Start)
- 20-Lead QFN Package
- 20-Lead TSSOP Package
Features
- Low Ripple Burst Mode® Operation:
7μA IQ at 12VIN to 5VOUT
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
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 (VIN 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 VIN 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 VOUT 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.
Applications
- Automotive ECU Power
- Power for Portable Products
- Industrial Supplies
For More Details: LT8494 – SEPIC/Boost DC/DC Converter with 2A, 70V Switch, and 7μA Quiescent Current
- What is the maximum output ripple of the LT8494?
The output ripple is typically below 10mV during low ripple Burst Mode operation. - How can the switching frequency be adjusted?
The frequency is programmable between 250kHz and 1.5MHz using an external resistor or configuration. - Can the LT8494 operate from a battery that drops below 2.5V after start-up?
Yes, dual supply pins allow the device to draw current from its output (BIAS) even when VIN drops below 2.5V. - Does the LT8494 support multiple converter topologies?
Yes, it can be configured as a SEPIC, boost, or flyback converter. - What is the minimum input voltage required for start-up?
The start-up voltage range is 2.5V to 32V depending on the topology, with a general operating range down to ~1V. - How is undervoltage lockout (UVLO) programmed?
A resistor divider connected to the SWEN pin provides a programmable UVLO setting. - Is there a power good flag available?
Yes, a PG functional flag signals when VOUT reaches 92% of the programmed output voltage. - What package options are available for the LT8494?
The device is available in 20-lead QFN and 20-lead TSSOP packages with exposed pads.
