SLUA475 November 2016 BQ2060A , BQ20Z80 , BQ40Z50-R1 , BQ40Z50-R2 , BQ40Z60 , BQ78350-R1 , BQ78350-R1A
The long clock stretch shown in Example 4 (Figure 10) is uncommon but still easily complies with the SMBus specification (25-ms packet length). Example 4 is a clear example of a clock stretch. As in this example, most clock stretches happen somewhere around the ACK and NACK clocks.