CS52313

The CS52313 combines a threeterminal linear regulator with circuitry controlling an external PFET transistor thus managing two input supplies. The part provides a 3.3 V regulated output either from the main 5.0 V supply or a 3.3 V auxiliary that switches on when the 5.0 V supply is not present. This delivers constant, uninterrupted power to the load. The CS52313 meets Intel's "Instantly Available" power requirements which follows from the "Advanced Configuration and Power Interface" (ACPI) standards developed by Intel, Microsoft and Toshiba.

The CS52313 linear regulator provides a fixed 3.3 V output at 500 mA with an overall accuracy of ± 2.0%. The internal NPNPNP composite pass transistor provides a low dropout voltage and requires less supply current than a straight PNP design. Full protection with both current limit and thermal shutdown is provided.

Designed for low reverse current, the IC prevents excessive current from flowing from VOUT to either VIN or ground when the regulator input voltage is lower than the output voltage.

The CS52313 can be used to provide power to an ASIC on a PCI Network Interface Card (NIC). When the system enters a Sleep State and the 5.0 V input drops below 4.4 V, the AuxDrv control signal on the CS52313 is activated turning on the external PFET. This switches the supply source from the 5.0 V input to the 3.3 V input through the PFET, guaranteeing a constant 3.3 V output to the ASIC that is "glitch free."The CS52313 is available in two package types: the 5Lead D² PAK (TO263) package and the 8Lead SOIC 4Leadfused (DF) package.

Other applications include desktop computers, power supplies with multiple input sources and PCMCIA/PCI interface cards.