Semtech | SC121ULTRT

SC121ULTRT is a high efficiency, low noise, synchronous step-up DC-DC converter that provides boosted voltage levels in low-voltage handheld applications. The wide input voltage range allows use in systems with single NiMH or alkaline battery cells as well as in systems with higher voltage battery supplies.

It features an internal 1.2 A switch and synchronous rectifier to achieve up to 94% efficiency and to eliminate the need for an external Schottky diode. The output voltage can be set to 3.3 V with internal feedback, or to any voltage within the specified range using a standard resistor divider. The SC121 operates exclusively in Pulse Width Modulation (PWM) mode for low ripple and fixed-frequency switching.

Features:

• Input voltage 0.7 V to 4.5 V
• Minimum start-up voltage 0.85 V
• Output voltage fixed at 3.3 V; adjustable from 1.8 V to 5.0 V
• Peak input current limit  1.2 A
• Output current at 3.3 Vout: 80 mA with Vin = 1.0 V, 190 mA with Vin = 1.5 V
• Forced PWM operation at all loads
• Efficiency up to 94%
• Internal synchronous rectifier
• No forward conduction path during shutdown
• Switching frequency 1.2 MHz
• Soft-start startup current limiting
• Shutdown current 0.1 μA (typ)

Applications:

• MP3 players
• Smart phones and cellular phones
• Palmtop computers and handheld instruments
• PCMCIA cards and memory cards
• Digital cordless phones
• Personal medical products
• Wireless VoIP phones
• Small motors