Hi TI,
I am investigating the usage of BQ25910. I am curious about the control principles. Here are my two questions.
1. In the datasheet of BQ25910, it is stated that the device is operated for a fixed frequency. "The fixed frequency oscillator keeps tight control of the switching frequency under all conditions of input voltage, battery voltage, charge current and temperature". The word "control" confuses me. If the device is operated with a peak or valley current mode control, the frequency is fixed and do not need to be controlled. If the device is operated with a pseudo-fixed frequency control (such as adaptive constant on/off time control), the frequency seems unable to be constant over the full load.
In summary, what is the control method used in BQ25910? I guess the optional answers are: peak current mode, valley current mode, adaptive constant on time, adaptive constant off time.
2. Among the aformentioned control method, when the duty ratio is 0.5, the inductor current will become flat. I wonder how the device operates within this duty ratio regions.
Thanks,
Hans Zhang
