Features

• Wide Input Range: 3.3V to 60V
• 1.5A Peak Switch Current (LT1976)
• 100µA Quiescent Current (LT1976)
• 1.6mA Quiescent Current (LT1976B)
• Low Shutdown Current: IQ < 1µA
• Power Good Flag with Programmable Threshold
• Load Dump Protection to 60V
• 200kHz Switching Frequency
• Saturating Switch Design: 0.2Ω On-Resistance
• Peak Switch Current Maintained Over Full Duty Cycle Range
• 1.25V Feedback Reference Voltage
• Easily Synchronizable
• Soft-Start Capability
• Small 16-Pin Thermally Enhanced TSSOP Package

Typical Application

Description

Innovative design techniques along with a new high voltage process achieve high efficiency over a wide input range. Efficiency is maintained over a wide output current range by employing Burst Mode operation at low currents, utilizing the output to bias the internal circuitry, and by using a supply boost capacitor to fully saturate the power switch. The LT1976B does not shift into Burst Mode operation at low currents, eliminating low frequency output ripple at the expense of efficiency. Patented circuitry maintains peak switch current over the full duty cycle range.* Shutdown reduces input supply current to less than 1µA. External synchronization can be implemented by driving the SYNC pin with logic-level inputs. A single capacitor from the CSS pin to the output provides a controlled output voltage ramp (soft-start). The devices also have a power good flag with a programmable threshold and time-out and thermal shutdown protection.

The LT1976/LT1976B are available in a 16-pin TSSOP package with Exposed Pad leadframe for low thermal resistance.