Hi,
I am using TPS65262-2RHBT in my design. I have to the control the power sequence externally and maintain certain sequence. Please let me know how can I control the sequence externally. Also I have to control the sequence of all 3 buck regulators. Buck2 should be enabled first. Buck 3 should be enabled only after Buck2. Buck 1 will be enabled at the end of power sequence. Hence please let me know can it be controlled by providing external voltage divider.
Hi,
Thanks for reaching out.
Method 1: Will Buck1, 2 and 3 share same VIN? If yes, you can adjust UVLO by change the value of R1 and R2.
The EN pin has a small pullup current Ip which sets the default state of the pin to enable when no external components are connected. The pullup current is also used to control the voltage hysteresis for the UVLO function since it increases by Ih once the EN pin crosses the enable threshold. The UVLO thresholds can be calculated using equations shown below. Since your input voltage for each Buck is the same, different Vstart means that you can get different start up sequence.
Method 2: The converter enable pins are biased by a current source that allows for easy sequencing by the addition of an external capacitor. A typical 1.4-µA current is charging ENx pin from input supply. When ENx pin voltage rise to typical 0.4 V, the internal V7V LDO turns on. A 3.6-µA pullup current is sourcing ENx. After ENx pin voltage reaches to 1.2 V typical, 3-µA hysteresis current sources to the pin to improve noise sensitivity. If all output voltages are in the regulation, PGOOD is asserted after PGOOD deglitch time. When an external capacitor is connected to EN pin, the value of CEN will have effect on this delay time. You can also find the start up power sequence shown below:
Please kindly let us know if there is any more concern. Thanks!
BRs
Lucia
