CS5231-3GDFR8

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

The CS5231-3GDFR8 is a fixed 3.3 V linear regulator with auxiliary control, manufactured by onsemi in the SOIC-8 (DF) package. It provides a regulated output of 3.3 V ± 2.0% at up to 500 mA load current. The device manages two input supplies, switching from a main 5.0 V source to a 3.3 V auxiliary supply via an external PFET when the main input drops below approximately 4.5 V. Key electrical parameters include a quiescent current of 3.0 mA at full load, a reverse output current of 450 µA, and internal current limit protection. The component operates within a junction temperature range up to 150°C.

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

• Combines a three-terminal linear regulator with circuitry controlling an external PFET transistor for dual-supply management.
• Provides glitch-free transition between a primary 5.0 V input and a 3.3 V auxiliary supply to maintain uninterrupted power.
• Features internally fused leads in the SOIC-8 package design.
• Includes comprehensive protection mechanisms such as current limit and thermal shutdown with hysteresis.

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

• Powering ASICs on PCI Network Interface Cards (NICs).
• Desktop computer systems requiring Instantly Available power states.
• PCMCIA/PCI interface cards.
• Power supplies utilizing multiple input sources.

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

Verify that the ordering suffix GDFR8 corresponds specifically to the SOIC-8 package with tape and reel shipping configuration containing 2500 units per reel. Confirm compliance with RoHS standards and halogen-free material requirements as specified in the manufacturer's documentation. Ensure the application circuit includes the necessary external p-channel FET and capacitors to meet stability constraints regarding capacitance and equivalent series resistance.

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

Select this component when a fixed 3.3 V output with high accuracy is required alongside seamless switchover capabilities between two power rails. It is suitable for designs adhering to ACPI standards where maintaining voltage during sleep state transitions is critical. Consider the thermal performance characteristics of the SOIC-8 package and ensure adequate PCB copper area or heatsinking if operating near maximum power dissipation limits under high ambient temperatures.

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

This part belongs to the CS5231-3 family of linear regulators designed for system power management. It integrates an NPN-PNP composite pass transistor to achieve low dropout voltage and reduced supply current compared to straight PNP designs. The device is engineered to prevent excessive reverse current flow from the output to the input or ground when input voltage is insufficient, enhancing overall system efficiency and reliability.

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

CS5231-3GDP5: D2PAK-5 package variant. CS5231-3GDPR5: D2PAK-5 tape and reel variant. CS5231-3GDF8: SOIC-8 rail pack variant.

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

How does the CS5231-3 manage the transition between the main and auxiliary supplies?

When the VIN supply drops below a typical threshold of 4.5 V, the AuxDrv signal activates an external PFET, switching the load to the 3.3 V auxiliary supply. When VIN rises above this threshold, the PFET turns off and the linear regulator takes over, ensuring a glitch-free transition.

What are the stability requirements for the output capacitor?

For stable operation, the output capacitor must be greater than 10 µF with an equivalent series resistance (ESR) less than 1.0 Ω. This capacitance also serves as a charge reservoir to minimize glitches during supply changes.