Kernel drivers ltc4283

Supported chips:

• Analog Devices LTC4283

  Prefix: ‘ltc4283’

  Addresses scanned: -

  Datasheet:

  https://www.analog.com/media/en/technical-documentation/data-sheets/ltc4283.pdf

Author: Nuno Sá <nuno.sa@analog.com>

Description

The LTC4283 negative voltage hot swap controller drives an external N-channel MOSFET to allow a board to be safely inserted and removed from a live backplane. The device features programmable current limit with foldback and independently adjustable inrush current to optimize the MOSFET safe operating area (SOA). The SOA timer limits MOSFET temperature rise for reliable protection against overstresses. An I2C interface and onboard gear-shift ADC allow monitoring of board current, voltage, power, energy, and fault status. Additional features respond to input UV/OV, interrupt the host when a fault has occurred, notify when output power is good, detect insertion of a board, turn off the MOSFET if an external supply monitor fails to indicate power good within a timeout period, and auto-reboot after a programmable delay following a host commanded turn-off.

Sysfs entries

The following attributes are supported. Limits are read-write and all the other attributes are read-only. Note that the VADIOx channels might not be available if the ADIO pins are used as GPIOs (naturally also affects the respective differential channels).

in0_lcrit_alarm	Critical Undervoltage alarm
in0_crit_alarm	Critical Overvoltage alarm
in0_reset_history	Clears Under and Overvoltage fault logs.
in0_label	Channel label (VIN)
in1_input	Output voltage (mV).
in1_min	Undervoltage threshold
in1_max	Overvoltage threshold
in1_lowest	Lowest measured voltage
in1_highest	Highest measured voltage
in1_reset_history	Write 1 to reset history.
in1_min_alarm	Undervoltage alarm
in1_max_alarm	Overvoltage alarm
in1_label	Channel label (VPWR)
in2_input	Output voltage (mV).
in2_min	Undervoltage threshold
in2_max	Overvoltage threshold
in2_lowest	Lowest measured voltage
in2_highest	Highest measured voltage
in2_reset_history	Write 1 to reset history.
in2_min_alarm	Undervoltage alarm
in2_max_alarm	Overvoltage alarm
in2_enable	Enable/Disable monitoring.
in2_label	Channel label (VADI1)
in3_input	Output voltage (mV).
in3_min	Undervoltage threshold
in3_max	Overvoltage threshold
in3_lowest	Lowest measured voltage
in3_highest	Highest measured voltage
in3_reset_history	Write 1 to reset history.
in3_min_alarm	Undervoltage alarm
in3_max_alarm	Overvoltage alarm
in3_enable	Enable/Disable monitoring.
in3_label	Channel label (VADI2)
in4_input	Output voltage (mV).
in4_min	Undervoltage threshold
in4_max	Overvoltage threshold
in4_lowest	Lowest measured voltage
in4_highest	Highest measured voltage
in4_reset_history	Write 1 to reset history.
in4_min_alarm	Undervoltage alarm
in4_max_alarm	Overvoltage alarm
in4_enable	Enable/Disable monitoring.
in4_label	Channel label (VADI3)
in5_input	Output voltage (mV).
in5_min	Undervoltage threshold
in5_max	Overvoltage threshold
in5_lowest	Lowest measured voltage
in5_highest	Highest measured voltage
in5_reset_history	Write 1 to reset history.
in5_min_alarm	Undervoltage alarm
in5_max_alarm	Overvoltage alarm
in5_enable	Enable/Disable monitoring.
in5_label	Channel label (VADI4)
in6_input	Output voltage (mV).
in6_min	Undervoltage threshold
in6_max	Overvoltage threshold
in6_lowest	Lowest measured voltage
in6_highest	Highest measured voltage
in6_reset_history	Write 1 to reset history.
in6_min_alarm	Undervoltage alarm
in6_max_alarm	Overvoltage alarm
in6_enable	Enable/Disable monitoring.
in6_label	Channel label (VADIO1)
in7_input	Output voltage (mV).
in7_min	Undervoltage threshold
in7_max	Overvoltage threshold
in7_lowest	Lowest measured voltage
in7_highest	Highest measured voltage
in7_reset_history	Write 1 to reset history.
in7_min_alarm	Undervoltage alarm
in7_max_alarm	Overvoltage alarm
in7_enable	Enable/Disable monitoring.
in7_label	Channel label (VADIO2)
in8_input	Output voltage (mV).
in8_min	Undervoltage threshold
in8_max	Overvoltage threshold
in8_lowest	Lowest measured voltage
in8_highest	Highest measured voltage
in8_reset_history	Write 1 to reset history.
in8_min_alarm	Undervoltage alarm
in8_max_alarm	Overvoltage alarm
in8_enable	Enable/Disable monitoring.
in8_label	Channel label (VADIO3)
in9_input	Output voltage (mV).
in9_min	Undervoltage threshold
in9_max	Overvoltage threshold
in9_lowest	Lowest measured voltage
in9_highest	Highest measured voltage
in9_reset_history	Write 1 to reset history.
in9_min_alarm	Undervoltage alarm
in9_max_alarm	Overvoltage alarm
in9_enable	Enable/Disable monitoring.
in9_label	Channel label (VADIO4)
in10_input	Output voltage (mV).
in10_min	Undervoltage threshold
in10_max	Overvoltage threshold
in10_lowest	Lowest measured voltage
in10_highest	Highest measured voltage
in10_reset_history	Write 1 to reset history.
in10_min_alarm	Undervoltage alarm
in10_max_alarm	Overvoltage alarm
in10_enable	Enable/Disable monitoring.
in10_label	Channel label (DRNS)
in11_input	Output voltage (mV).
in11_min	Undervoltage threshold
in11_max	Overvoltage threshold
in11_lowest	Lowest measured voltage
in11_highest	Highest measured voltage
in11_reset_history	Write 1 to reset history. Also clears fet bad and short fault logs.
in11_min_alarm	Undervoltage alarm
in11_max_alarm	Overvoltage alarm
in11_enable	Enable/Disable monitoring
in11_fault	Failure in the MOSFET. Either bad or shorted FET.
in11_label	Channel label (DRAIN)
in12_input	Output voltage (mV).
in12_min	Undervoltage threshold
in12_max	Overvoltage threshold
in12_lowest	Lowest measured voltage
in12_highest	Highest measured voltage
in12_reset_history	Write 1 to reset history.
in12_min_alarm	Undervoltage alarm
in12_max_alarm	Overvoltage alarm
in12_enable	Enable/Disable monitoring.
in12_label	Channel label (ADIN2-ADIN1)
in13_input	Output voltage (mV).
in13_min	Undervoltage threshold
in13_max	Overvoltage threshold
in13_lowest	Lowest measured voltage
in13_highest	Highest measured voltage
in13_reset_history	Write 1 to reset history.
in13_min_alarm	Undervoltage alarm
in13_max_alarm	Overvoltage alarm
in13_enable	Enable/Disable monitoring.
in13_label	Channel label (ADIN4-ADIN3)
in14_input	Output voltage (mV).
in14_min	Undervoltage threshold
in14_max	Overvoltage threshold
in14_lowest	Lowest measured voltage
in14_highest	Highest measured voltage
in14_reset_history	Write 1 to reset history.
in14_min_alarm	Undervoltage alarm
in14_max_alarm	Overvoltage alarm
in14_enable	Enable/Disable monitoring.
in14_label	Channel label (ADIO2-ADIO1)
in15_input	Output voltage (mV).
in15_min	Undervoltage threshold
in15_max	Overvoltage threshold
in15_lowest	Lowest measured voltage
in15_highest	Highest measured voltage
in15_reset_history	Write 1 to reset history.
in15_min_alarm	Undervoltage alarm
in15_max_alarm	Overvoltage alarm
in15_enable	Enable/Disable monitoring.
in15_label	Channel label (ADIO4-ADIO3)
curr1_input	Sense current (mA)
curr1_min	Undercurrent threshold
curr1_max	Overcurrent threshold
curr1_lowest	Lowest measured current
curr1_highest	Highest measured current
curr1_reset_history	Write 1 to reset curr1 history. Also clears overcurrent fault logs.
curr1_min_alarm	Undercurrent alarm
curr1_max_alarm	Overcurrent alarm
curr1_crit_alarm	Critical Overcurrent alarm
curr1_label	Channel label (ISENSE)
power1_input	Power (in uW)
power1_min	Low power threshold
power1_max	High power threshold
power1_input_lowest	Historical minimum power use
power1_input_highest	Historical maximum power use
power1_reset_history	Write 1 to reset power1 history. Also clears power fault logs.
power1_min_alarm	Low power alarm
power1_max_alarm	High power alarm
power1_label	Channel label (Power)
energy1_input	Measured energy over time (in microJoule)
energy1_enable	Enable/Disable Energy accumulation

DebugFs entries

The chip also has a fault log register where failures can be logged. Hence, as these are logging events, we give access to them in debugfs. Note that even if some failure is detected in these logs, it does necessarily mean that the failure is still present. As mentioned in the proper Sysfs entries, these logs can be cleared by writing in the proper reset_history attribute.

Warning

The debugfs interface is subject to change without notice and is only available when the kernel is compiled with CONFIG_DEBUG_FS defined.

/sys/kernel/debug/i2c/i2c-[X]/[X]-addr/ contains the following attributes: