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ltc4261

ltc4261 2.1 KB
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  1. Kernel driver ltc4261
    2. 

  2. =====================
    3. 

  3. 

  4. Supported chips:
    5. 

  5.   * Linear Technology LTC4261
    6. 

  6.     Prefix: 'ltc4261'
    7. 

  7.     Addresses scanned: -
    8. 

  8.     Datasheet:
    9. 

  9.         http://cds.linear.com/docs/Datasheet/42612fb.pdf
    10. 

  10. 

  11. Author: Guenter Roeck <linux@roeck-us.net>
    12. 

  12. 

  13. 

  14. Description
    15. 

  15. -----------
    16. 

  16. 

  17. The LTC4261/LTC4261-2 negative voltage Hot Swap controllers allow a board
    18. 

  18. to be safely inserted and removed from a live backplane.
    19. 

  19. 

  20. 

  21. Usage Notes
    22. 

  22. -----------
    23. 

  23. 

  24. This driver does not probe for LTC4261 devices, since there is no register
    25. 

  25. which can be safely used to identify the chip. You will have to instantiate
    26. 

  26. the devices explicitly.
    27. 

  27. 

  28. Example: the following will load the driver for an LTC4261 at address 0x10
    29. 

  29. on I2C bus #1:
    30. 

  30. $ modprobe ltc4261
    31. 

  31. $ echo ltc4261 0x10 > /sys/bus/i2c/devices/i2c-1/new_device
    32. 

  32. 

  33. 

  34. Sysfs entries
    35. 

  35. -------------
    36. 

  36. 

  37. Voltage readings provided by this driver are reported as obtained from the ADC
    38. 

  38. registers. If a set of voltage divider resistors is installed, calculate the
    39. 

  39. real voltage by multiplying the reported value with (R1+R2)/R2, where R1 is the
    40. 

  40. value of the divider resistor against the measured voltage and R2 is the value
    41. 

  41. of the divider resistor against Ground.
    42. 

  42. 

  43. Current reading provided by this driver is reported as obtained from the ADC
    44. 

  44. Current Sense register. The reported value assumes that a 1 mOhm sense resistor
    45. 

  45. is installed. If a different sense resistor is installed, calculate the real
    46. 

  46. current by dividing the reported value by the sense resistor value in mOhm.
    47. 

  47. 

  48. The chip has two voltage sensors, but only one set of voltage alarm status bits.
    49. 

  49. In many many designs, those alarms are associated with the ADIN2 sensor, due to
    50. 

  50. the proximity of the ADIN2 pin to the OV pin. ADIN2 is, however, not available
    51. 

  51. on all chip variants. To ensure that the alarm condition is reported to the user,
    52. 

  52. report it with both voltage sensors.
    53. 

  53. 

  54. in1_input		ADIN2 voltage (mV)
    55. 

  55. in1_min_alarm		ADIN/ADIN2 Undervoltage alarm
    56. 

  56. in1_max_alarm		ADIN/ADIN2 Overvoltage alarm
    57. 

  57. 

  58. in2_input		ADIN voltage (mV)
    59. 

  59. in2_min_alarm		ADIN/ADIN2 Undervoltage alarm
    60. 

  60. in2_max_alarm		ADIN/ADIN2 Overvoltage alarm
    61. 

  61. 

  62. curr1_input		SENSE current (mA)
    63. 

  63. curr1_alarm		SENSE overcurrent alarm
    64.