When designing a complicated system with many power rails, you must not overlook how and when rails are turned on. Sequencing sub-systems can be implemented in various ways. Theoretically a system can chain PGOOD signals from Power IC's to the enable subsequent power rails. This is not recommended, however, as there's no easy way to disable the system once it's been turned on.

TPS38700S-Q1 operates similarly to a PGOOD based protocol, but is able to bypass the powering down dilemma by having a handshake based PGOOD protocol with SYNC for both sequencing up and down. TPS38700S-Q1 waits for the SYNC signal from the TPS389006-Q1 Device indicating the voltage met a UV PGOOD or OFF threshold before firing the next signal.

Another way a system can also implement sequencing is with a blind firing approach. The blind firing approach turns on subsequent rails after a small time delay regardless of whether or not the rails power on. This can be useful in systems where power rails don't have any critical voltage dependencies, but the order of how the rails are turned on and off is important. You can implement a Non-Monitored sequencing approach like this with the N OTP variant ofTPS38700S-Q1.

TPS38700S-Q1 is a versatile part that can be configured for multiple ways. The part can be ordered as a pure sequencer, pure GPO expander, or combination sequencer & GPOs. Sequencing outputs can be assigned to ACT pin. These sequencing outputs can be factory configured for default values and subsequently changed via I²C on power-up before sending ACT pin high.

The TPS38700S-Q1 is capable of various I²C logic levels. A full featured Graphical User Interface (GUI) is available for download in the product folder. Contact a Texas Instruments representative for custom configured part queries.

The TPS38700S-Q1 is AEC-Q100 qualified for automotive applications and has been characterized from
-40ºC to +125ºC.