Summit Microelectronics - Applications Note 30

Tech Support: Applications Note 30
SMH4804 -48V Programmable Hot Swap Sequencing Power Controller -48V Hot-Swap Controller Features Simple Software I²C Power-On/Off Interface

Application Note 30

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SMH4804 -48V Programmable Hot Swap Sequencing Power Controller

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Figure 3: Clearing the Fault Bit.

Deploying the Power-On/Off Feature

Having write access to the fault register bit allows the user the option of powering the system using a simple I²C write command via the Windows GUI (Figure 4) and on-board I²C interface.
Power-On/Off Without Fault Recording

The 'I2C Power On/Off' radio buttons allow the user to power-on/off the SMH4804 by simply clicking either button. This action is the equivalent of performing an I²C write sequence to Register C, bit 0. This feature is easily implemented on a system card, requiring only a simple I²C hardware interface to the SMH4804. See the SMH4804 Data Sheet (PDF) for hardware and software details.
Power-On/Off With Fault Recording

The I²C Power On/Off feature is also available when Fault Recording is enabled (Figure 5). The performance is virtually unaffected except the SMH4804 will shutdown upon the occurrence of an over-current fault.

Note, the SMH4804 will not restart until the fault is removed and the fault bit cleared (Register C, bit 0).

Performance Comparison Summary

The SMH4804 VGATE voltage was monitored to measure any difference in performance during the power-on/off events using live-insertion or the I²C Power On/Off feature (Figures 6-9). As the oscilloscope photos demonstrate, the SMH4804 reacts identically to either 'event'.

NOTICE

SUMMIT Microelectronics, Inc. reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. SUMMIT Microelectronics, Inc. assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained herein reflect representative operating parameters, and may vary depending upon a user's specific application. While the information in this publication has been carefully checked, SUMMIT Microelectronics, Inc. shall not be liable for any damages arising as a result of any error or omission.

SUMMIT Microelectronics, Inc. does not recommend the use of any of its products in life support or aviation applications where the failure or malfunction of the product can reasonably be expected to cause any failure of either system or to significantly affect their safety or effectiveness. Products are not authorized for use in such applications unless SUMMIT Microelectronics, Inc. receives written assurances, to its satisfaction, that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; and (c) potential liability of SUMMIT Microelectronics, Inc. is adequately protected under the circumstances.

Revision 1.0 - This document supersedes all previous versions and covers Windows GUI revision 2.3.0 and later. Please check the Summit Microelectronics, Inc. web site at www.summitmicro.com for updates.

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