LT1575CN8-3.5#PBF

Overview

The LT1575CN8-3.5#PBF is a fixed-output low dropout regulator controller IC manufactured by Analog Devices Inc., housed in an 8-pin PDIP package. It provides a precise 3.5V output with ±0.6% tolerance at room temperature and ±1.0% over the operating temperature range. The device operates within a 10V to 20V input voltage range, drawing a typical quiescent current of 12.5mA. Key electrical parameters include a 50mV current limit threshold voltage, a 1.21V internal reference voltage, and a large-signal voltage gain of approximately 74dB.

Feature Summary

• Ultrafast transient response capability that eliminates the need for expensive tantalum or bulk electrolytic output capacitors in demanding microprocessor applications.
• Low dropout voltage performance determined by the external N-channel MOSFET RDS(ON), allowing for high efficiency in low differential voltage scenarios.
• Integrated multifunction shutdown pin providing latchoff protection against current limit time-outs, overvoltage conditions, and thermal shutdown events.

Applications

• Pentium processor power supplies
• PowerPC processor supplies
• Microprocessor core supplies stepping down from 5V to 3.3V or 3.3V to lower voltages
• GTL termination circuits
• Low voltage logic supplies

Procurement Notes

Verify the specific ordering suffix matches the required package type, as the CN8 designation indicates an 8-lead PDIP configuration. Confirm compliance with RoHS directives and check for any industrial or military grade variants if extended temperature ranges beyond the standard commercial specification are required for the target application environment.

Selection Notes

Select this component when designing power stages requiring ultrafast load transient response without bulk output capacitance. Ensure the chosen external N-channel MOSFET has a gate threshold voltage compatible with the GATE pin drive levels and sufficient current handling for the application. Verify that the system input voltage remains within the specified 10V to 20V operational limits to maintain proper regulation and protection function timing.

Part Context

This part belongs to the LT1575/LT1577 family of single and dual controller ICs designed to drive external N-channel MOSFETs as source followers. While the LT1575 offers single-channel regulation in compact packages, the LT1577 provides dual-channel functionality in a 16-pin narrow SOIC. Both families share the same core architecture for achieving low dropout and high-speed transient performance.

Replacement Considerations

Direct functional substitutes within the same product line include the LT1575CS8-3.5#PBF, which shares identical electrical specifications but utilizes an 8-lead plastic SOIC surface mount package instead of the through-hole PDIP format. Designers must account for the physical footprint differences when swapping between these package options.