FAN2509S28X

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Overview

The FAN2509S28X is a fixed-output 2.8V CMOS LDO regulator with a 50mA output current capability. It features a maximum dropout voltage of 75mV at full load and a ground pin current of 50µA. The device includes an Enable/Shutdown control pin that reduces supply current to less than 1µA when disabled. Pin 4 serves as an open-drain Error flag, indicating if the output voltage drops below 95% of nominal due to faults such as input dropout or thermal overload. It operates within a -40°C to +125°C junction temperature range.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Feature Summary

• Utilizes CMOS technology for ultra-low power consumption and low shutdown current
• Features an open-drain error flag output to indicate fault conditions like thermal limiting or undervoltage
• Includes enable/shutdown control allowing user-defined power-down states
• Offers exceptional loop stability compatible with a wide variety of external capacitors

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Applications

• Cellular phones and accessories
• Portable cameras and video recorders
• Laptop, notebook and palmtop computers

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Procurement Notes

Verify the specific suffix '28X' confirms the 2.8V fixed output voltage and tape-and-reel packaging format. Ensure the ERR pin configuration matches system diagnostic requirements. Confirm the SOT-23-5 package dimensions align with PCB layout constraints. Validate operating temperature ranges against environmental specifications.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Selection Notes

Select this component for battery-powered applications requiring minimal quiescent current and reliable fault detection. The integrated error flag simplifies monitoring output integrity without additional circuitry. Consider the low dropout characteristics for systems with narrow input-to-output voltage margins. Evaluate capacitor selection based on ESR tolerance to ensure stable operation across varying loads.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Part Context

This device belongs to the FAN2508/FAN2509 family of micropower low-dropout voltage regulators. While the FAN2508 offers adjustable or bypassed outputs, the FAN2509 variant specifically provides an error flag function at Pin 4. Both utilize P-Channel MOSFET pass transistors for superior performance compared to older BiCMOS designs.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Replacement Considerations

The datasheet notes the FAN2508/09 family is pin-compatible with many popular devices. Verify compatibility with existing BiCMOS designs during replacement. Check if alternative LDOs provide similar error flag functionality or if software polling can replace hardware diagnostics.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators FAQ

What is the function of Pin 4 on the FAN2509S28X?

Pin 4 is an open-drain Error (ERR) flag output. It indicates a fault condition by going LOW when the output voltage drops below 95% of the nominal rated voltage.

How does the device handle thermal overload?

Onboard thermal protection shuts down the output if the die temperature exceeds 150°C. The output remains suspended until the temperature drops below this limit, at which point it re-enables automatically.