Smart appliances offer new features and high performance that have been integrated into appliances gradually, such as voice recognition, wireless connectivity, advanced Human Machine Interface (HMI), advanced interaction, and so forth. Processors with high performance and wireless connectivity devices are widely used in smart appliance control platforms. TI’s SitaraTM AM335x family and WiLink8TM family are ideal choices for control systems in smart appliance .
The processors or digital devices usually require different power supply voltages, mixed together on the board with the correct power sequence. Power supply voltages turned on with an incorrect power sequence can cause reliability problems such as characteristics degradation, inrush currents, and latch-up conditions. The challenge is how to design the power tree with correct sequencing without trading off factors such as power tree architect, efficiency, cost, size, and more.
This reference design provides a 5-rail multi-channel power sequencing solution. The small form factor of 12 mm × 12 mm is achieved by using the TLV62568/9, offering 1.5-MHz switching frequency in a small package of SOT-563. The correct power sequence is achieved by using the LM3881, offering three open-drain output flags with individual time delays to avoid latch conditions or large inrush currents that can affect the reliability of the system. This power sequencing solution also supports the uncontrolled power off by using a supervisor of the TLV803 to monitor the input voltage rail, while also generating the power reset signal to manage the power up and power down sequence.
The test report evaluates this power sequencing platform, powering the AM335x and WL1837MOD with all necessary components as a system control platform such as: 4GB eMMC, 256M × 16-Bit DDR3L, microSD™ Card, EEPROM, and USB host. The test result provides the details of the power up and power down sequence, and the typical characters of DC-DCs.