The IOUT_OC_WARN_LIMIT command sets the average value of the output current that causes the overcurrent detector to indicate an overcurrent warn condition.

Return to Supported PMBus Commands.

Data Validity

Every mantissa binary value in the writable bits is writeable and readable. However, the actual divider is set to the nearest supported value. Additionally, that mantissa value restored from EEPROM is fixed for each setting supported in hardware.

Attempts to change the read-only bits (IOUT_OC_WARN_LIMIT[15:6]) will be considered invalid/unsupported data. The device will NACK the unsupported data and the received value will be ignored. The ’cml’ bit in the STATUS_BYTE and the ‘ivd’ bit in the (7Eh) STATUS_CML registers will be set.

Response to P2_PLUS_WRITE Commands

When the PMBus host attempts to execute a P2+ write to IOUT_OC_WARN_LIMIT with the PHASE data in the command set to FFh, the expectation is to equally divide the commanded net “Stack OCW” level among the phases as their individual “Phase OCW” settings. In order to achieve that, the device does the following:

• If STACK_NUMBER[1:0] is 2 (i.e., 2-phase operation), then the incoming commanded Stack OCW level is converted to the individual Phase OCW level by adding 1, followed by right-shift of 1 bit (i.e., dividing by 2, rounded up). The resulting Phase OCW level is then binned into the appropriate IOUT_OCW value based on the IOUT_OC_WARN_LIMIT tables above.
• If STACK_NUMBER<1:0> is 4 (i.e., 4-phase operation), then the incoming commanded Stack OCW level is converted to the individual Phase OCW level by adding 2, followed by right-shift of 2 bits (i.e., dividing by 4, rounded up). The resulting Phase OCW level is then binned into the appropriate IOUT_OCW value based on the IOUT_OC_WARN_LIMIT tables above.
• If STACK_NUMBER<1:0> is 3 (i.e., 3-phase operation), then the incoming commanded Stack OCW level is directly converted to the PHASE IOUT_OCW value using the table below:

Response to P2_PLUS_READ Commands

When the PMBus host attempts to execute a P2+ read on IOUT_OC_WARN_LIMIT with the PHASE data in the command set to FFh, only the primary device will respond to P2+ read commands with incoming data for PHASE=FFh. The primary device multiplies the IOUT_OCW level by the STACK_NUMBER and reports the product back on the PMBus. For example, if the IOUT_OCW is 25A for the primary phase in a 3-phase rail, then a P2+ read with PHASE=FFh will yield 25 x 3 = 75A as the read-back value.