Complex devices like CPUs, ASICs, FPGAs, and memories commonly require power-supply sequencing. MAX16046 provides a highly integrated solution for sequencing, monitoring, and power-supply margining. Here is an example system using multiple devices with specific sequencing requirements, and provides a step-by-step implementation using the MAX16046.  The MAX16046 provides a straightforward method of implementing sequencing, margining, and monitoring in complex, multiple power-supply systems. The configuration software simplifies the configuration of the tolerances and the sequence order.

Modern electronic devices have complex power requirements involving multiple voltage rails. Power must be supplied for I/O voltages; CPU, ASIC, and FPGA core voltages; PLL voltages; and memory-termination voltages. Other devices need high-voltage, high-current, or low-noise power supplies for applications like radio transceivers, ultrasonic transducers, and LCD or plasma displays.

Designs using multiple power supplies require the designer to pay close attention to power sequencing. Each power-supply rail must be turned on in a specific order to avoid forward-biasing protection diodes within complex multivoltage ICs. If the power supplies are simply turned on simultaneously, the ICs could suffer reliability problems or even latchup.

In addition to power sequencing, some systems implement margining. Voltage margining is a way of controlling the power-supply voltages to fully exercise the corners of all the tolerances and ensure system reliability.

Maxim offers several solutions for power management. This application note focuses on the MAX16046, which sequences, monitors, and margins up to 12 power rails.

The processor and FPGA specify a particular sequencing order to prevent forward biasing the internal ESD diodes for an extended period of time.

Implementing Monitoring, Sequencing, and Margining with the MAX16046
The MAX16046 monitors, sequences, and margins up to 12 power supply rails. Monitoring thresholds, the sequence order, margin parameters, and other configuration values are stored in the device's internal EEPROM. Real-time monitoring data can be read over the SMBus™ or JTAG interface, which can help check the sequencing order during development.

If a power-supply fault occurs during operation, the MAX16046 can automatically shut down the power supplies and assert configurable fault outputs. The device can also be configured to store information about the failure, including the rail voltages and the channel status, in the internal EEPROM for later analysis. This feature provides a useful tool for analyzing boards that failed in the field, but appear to work properly in the failure lab. Once a fault occurs, the EEPROM is locked so subsequent faults will not overwrite stored fault data.

The MAX16046 configuration software provides a convenient way of entering configuration parameters without studying register maps or performing endless calculations. Configuring the MAX16046 in our circuit board is accomplished in several steps.

So The MAX16046 provides a straightforward method of implementing sequencing, margining, and monitoring in complex, multiple power-supply systems. The MAX16046 configuration software simplifies the configuration of the tolerances and the sequence order.

Sequencing with the MAX16046 System-Management IC