Max Current From Ballast Transistor

[gordonp]

How much current can the external ballast transistor supply when used in conjunction with the 9S12ZVCA processor BCTL pin?

[danielmartynek]

Hi,

This is not defined, only max current IDDX without the external PNP (see Table E-1 of the RM). If the current exceeds this value, the external PNP is required. BCTL provides the base current of the transistor. The Table E-1 provides minimal base current that can be guaranteed. Then the gain of the transistor controls the maximum available current.

Please refer to Hardware Design Guidelines for S12ZVC for more information.

Regards,

Daniel