Mean Time Between Failures for a hybrid DC/DC converter may be estimated using the parts count method, or calculated using the stress method. In order to get a precise MTBF calculation, the following must be known:

• Component stress at the actual operating conditions.
• Component temperature at the actual operating conditions.
• Parts quality and screening.
• Actual application environment.
• The method and piece part failure rate data specified for performing the calculation.

This means that a lot of very specific analysis is required as a pre-requisite to getting an accurate MTBF value.

Fortunately, MDI can offer generic MTBF values based on some common assumptions:

• Operating base temperature 50° C.
• Overall power derating 75%.
• Parts quality and screening suitable for applications.
• MIL-HDBK-217F notice 2 used for calculations.

Based on these assumptions, the following are "generic" MTBF's for a typical 30 watt dual output converter:

MDI can provide specific MTBF calculations for a customer's actual operating conditions according to the customer's order.