LP2951ACM

The Texas Instruments LP2951ACM is a micropower low-dropout voltage regulator capable of supplying up to 100mA of load current with an input voltage range of 2.3V to 30V. The output voltage is adjustable from 1.24V to 29V using an external resistor divider. The device features an extremely low quiescent current of 75uA typical, making it ideal for battery-powered applications where supply current must be minimized. A shutdown pin allows the regulator to be turned off, reducing supply current to near zero. The error flag output provides an early warning when the output voltage drops below regulation, useful for power supply sequencing and supervision. The regulator is stable with ceramic output capacitors from 1uF to 100uF.

The LP2951ACM operates as a series-pass linear regulator with several control and monitoring features: 1) Voltage Regulation Core: The bandgap reference produces a stable 1.235V that is compared with the feedback voltage by the error amplifier. The pass transistor is driven to maintain the output at the programmed voltage. 2) Shutdown Control: The SHUTDOWN pin, when driven above 2V, disables the regulator and reduces input current to near zero. When driven below 0.8V, normal operation resumes. 3) Error Flag: The ERROR output goes low when the feedback voltage drops below approximately 92.5% of the nominal value, providing a dropout warning. This is useful for microprocessor reset or power-fail detection. 4) Protection: Internal current limiting and thermal shutdown protect the device from damage under overload or excessive power dissipation conditions.

• Battery-powered instruments requiring long operating life with low quiescent current
• Industrial control systems needing wide input voltage range regulation
• Power supply sequencing using error flag and shutdown control
• Automotive after-market modules operating from 12V or 24V systems
• Microcontroller and sensor power regulation in low-power designs