The ISL6506A and ISL6506B complement other power building blocks (voltage regulators) in ACPI-compliant designs for microprocessor and computer applications. They integrate the control of the 5VDUALand 3. 3VDUALrails into an 8 Ld EPAD SOIC package. The ISL6506A and ISL6506B's operating mode (active outputs or sleep outputs) is selectable through two digital control pins; S3 and S5. A completely integrated linear regulator generates the 3. 3VDUAL voltage plane from the ATX supply's 5VSBoutput during sleep states (S3, S4/S5). In active states (during S0 and S1/S2), the ISL6506A and ISL6506B use an external N-Channel pass MOSFET to connect the outputs directly to the 3. 3V input supplied by an ATX power supply, for minimal losses. The ISL6506A and ISL6506B power up the 5VDUALplane by switching in the ATX 5V output through an NMOS transistor in active states, or by switching in the ATX 5VSB through a PMOS (or PNP) transistor in S3 sleep state. In S4/S5 sleep states, the ISL6506B 5VDUAL output is shut down. In the ISL6506A, the 5VDUALoutput stays on during S4/S5 sleep states. The ISL6506A and ISL6506B are functionally identical, except for the sleep mode in the preceding paragraph. In addition, the ISL6506A has a 1A current limit on the internal 3. 3V LDO; the ISL6506B has a 2A current limit.