9.1.1.2.6 TurboTrans Output Capacitance

TurboTrans allows the designer to optimize the output capacitance according to the system transient design requirement. High quality, ultra-low ESR capacitors are required to maximize TurboTrans effectiveness. When using TurboTrans, the capacitor's capacitance (μF) × ESR (mΩ) product determines its capacitor type; Type A, B, or C. These three types are defined as follows:

Type A = (100 ≤ capacitance × ESR ≤ 1000) (for example, ceramic) (can be used in addition to Type B or Type C capacitors)

Type B = (1000 < capacitance × ESR ≤ 5000) (for example, polymer-tantalum)

Type C = (5000 < capacitance × ESR ≤ 10 000) (for example, OS-CON)

When using more than one type of output capacitor, select the capacitor type that makes up the majority of your total output capacitance. When calculating the C×ESR product, use the maximum ESR value from the capacitor manufacturer's data sheet.

Working Examples:

A capacitor with a capacitance of 330 μF and an ESR of 5 mΩ, has a C × ESR product of 1650 μF x mΩ (330 μF × 5 mΩ). This is a Type B capacitor. A capacitor with a capacitance of 1000 μF and an ESR of 8 mΩ, has a C × ESR product of 8000 μF x mΩ (1000 μF × 8 mΩ). This is a Type-C capacitor.

See the TurboTrans Technology Application section within this document for specific capacitance selection.

Table 4 includes a preferred list of capacitors by type and vendor. See the Output Bus/TurboTrans column.