LTC3620 Datasheet

• High Efficiency: Up to 95%
• Maximum Current Output: 15mA
• Externally Programmable Frequency Clamp with Internal 50kHz Default Minimizes Audio Noise
• 18μA I_Q Current
• 2.9V to 5.5V Input Voltage Range
• Low-Battery Detection
• 0.6V Reference Allows Low Output Voltages
• Shutdown Mode Draws <1μA Supply Current
• 2.8V Undervoltage Lockout
• Unique Low Noise Control Architecture
• Internal Power MOSFETs
• No Schottky Diodes Required
• Internal Soft-Start
• Tiny 2mm × 2mm 8-Lead DFN Package

• Hearing Aids
• Wireless Headsets
• Li-Ion Cell Applications
• Button Cell Replacement

The LTC3620 is a high efficiency, synchronous buck regulator, suitable for very low power, very small footprint applications powered by a single Li-Ion battery.

The internal synchronous switches increase efficiency and eliminate the need for external Schottky diodes. Low output voltages are easily supported by the 0.6V feedback reference voltage. The LTC3620-1 option is internally programmed to provide a 1.1V output.

The LTC3620 uses a unique variable frequency architecture to minimize power loss and achieve high efficiency. The switching frequency is proportional to the load current, and an internal frequency clamp forces a minimum switching frequency at light loads to minimize noise in the audio range. The user can program the frequency of this clamp by applying an external clock to the FMIN/MODE pin.

The battery status output, LOBATB, indicates when the input voltage drops below 3V. To help prevent damage to the battery, an undervoltage lockout (UVLO) circuit shuts down the part if the input voltage falls below 2.8V.

The LTC3620 is available in a low profile, 2mm × 2mm 8-lead DFN package.