LP2975IMMX-3.3

Overview

The LP2975IMMX-3.3 is a MOSFET LDO Driver/Controller manufactured by Texas Instruments, designed to drive external P-channel MOSFETs for high-current regulation. It features a standard output voltage of 3.3V with an accuracy of 1.5% (A Grade) or 2.5% (Standard Grade). The device operates within a supply voltage range of 1.8V to 24V and supports junction temperatures from -40°C to +125°C. Typical quiescent current is 180 µA at VIN = 5V, while shutdown current is less than 1 µA. It includes built-in current limit amplification with a 57 mV detection threshold and overtemperature protection.

Feature Summary

• Ultra-small VSSOP-8 package design
• Low-power shutdown input capability
• Built-in current limit amplifier
• Overtemperature protection

Applications

• High-current 5V to 3.3V Regulator
• Post Regulator for Switching Converter
• Current-limited Switch

Procurement Notes

Verify the specific grade (A or Standard) required for your application, as the datasheet specifies different voltage accuracies for each. Confirm that the 'X' suffix in the part number corresponds to tape-and-reel packaging if reel delivery is necessary for your assembly process. Ensure the external P-FET selected matches the controller's gate drive capabilities and thermal requirements.

Selection Notes

Select this component when designing high-current linear regulators using external P-channel MOSFETs. It is suitable for applications requiring precise output voltage regulation with minimal external components. Consider the thermal dissipation of the external FET carefully, as the controller does not protect the FET from overtemperature damage. Use the internal bandgap reference for stable performance across temperature ranges.

Part Context

The LP2975 series consists of MOSFET LDO Driver/Controllers available in various output voltage configurations, including 5.0V, 3.3V, and adjustable versions. The IMMX variant specifically denotes the surface-mount VSSOP-8 package with tape-and-reel packaging. This family allows designers to create custom high-current regulators by pairing the controller with appropriate external power MOSFETs.

Replacement Considerations

LP2975IMM-3.3/NOPB

FAQ

How is short-circuit current limiting implemented?

Short-circuit current limiting is implemented by placing a sense resistor (RSC) in series with VIN. The value is calculated using the formula RSC = VCL / ISC, where VCL is the 57 mV typical detection threshold.

What determines the dropout voltage of the regulator?

The dropout voltage is user-selectable and determined by sizing the external P-FET. It is defined as the maximum load current multiplied by the RDS(ON) of the FET plus the sense resistor value.