ZHCSGR0A February 2015 – August 2017 TPS2388
PRODUCTION DATA.
The recommended VDD supply voltage requirement is 3.3 V, ±0.3 V. TPS2388 requires approximately 6 mA typical and 12 mA maximum from the VDD supply. The VDD supply can be generated from VPWR with a buck-type regulator (LM5007 or LM5019 based) for a higher port count PSE using multiple TPS2388 devices operating in semiauto mode. The power supply design must ensure the VDD rail rises monotonically through the VDD UVLO thresholds without any droop under the UVLO_fall threshold as the loads are turned on. This is accomplished with proper bulk capacitance across the VDD rail for the expected load current steps over worst case design corners. Furthermore, the combination of decoupling capacitance and bulk storage capacitance must hold the VDD rail above the UVLO_fall threshold during any expected transient outages once power is applied.
The recommended VPWR supply voltage requirement is 44 V to 57 V. A power supply with a nominal 48-V or 54-V output can support both type 1 and type 2 PD requirements. The output current required from the VPWR supply depends on the number and type of ports required in the system. The TPS2388 can be configured for type 1 and type 2 ports and the current limit is set proportionally. ICUT is programmable, for example for a type 1 port it can be 380 mA , ±5%, while for a type 2 port it can be 640 mA, ±5%. Size the VPWR supply accordingly for the number and type of ports to be supported. As an example, the VPWR power supply rating should be greater than 3.2 A for eight type 1 ports or greater than 5.5 A for eight type 2 ports, assuming maximum port and standby currents.