LT1611 Datasheet

• Very Low Noise: 1mV_P–P Output Ripple
• –5V at 150mA from a 5V Input
• Better Regulation Than a Charge Pump
• Effective Output Impedance: 0.14Ω
• Uses Tiny Capacitors and Inductors
• Internally Compensated
• Fixed Frequency 1.4MHz Operation
• Low Shutdown Current: <1µA
• Low V_CESAT Switch: 300mV at 300mA
• Tiny 5-Lead SOT-23 Package

• MR Head Bias
• Digital Camera CCD Bias
• LCD Bias
• GaAs FET Bias
• Positive-to-Negative Conversion

The LT1611 is the industry’s first inverting 5-lead SOT-23 current mode DC/DC converter. Intended for use in small, low power applications, it operates from an input voltage as low as 1.1V and switches at 1.4MHz, allowing the use of tiny, low cost capacitors and inductors 2mm or less in height. Its small size and high switching frequency enable the complete DC/DC converter function to consume less than 0.25 square inches of PC board area. Capable of generating –5V at 150mA from a 5V supply or –5V at 100mA from a 3V supply, the LT1611 replaces nonregulated “charge pump” solutions in many applications.

The LT1611 operates in a dual inductor inverting topology which filters the input side as well as the output side of the DC/DC converter. Fixed frequency switching ensures a clean output free from low frequency noise typically present with charge pump solutions. No load quiescent current of the LT1611 is 3mA, while in shutdown quiescent current drops to 0.5µA. The 36V switch allows V_IN to V_OUT differential of up to 33V.

The LT1611 is available in the 5-lead SOT-23 package.