90
Rev. B
For more information
PMBus COMMAND DETAILS
IOUT_OC_FAULT_LIMIT
The IOUT_OC_FAULT_LIMIT command sets the value of the peak output current limit, in Amperes. When the control-
ler is in current limit, the overcurrent detector will indicate an overcurrent fault condition. The following table lists the
progammable peak output current limit value in mV between I
SENSE
+
and I
SENSE
–
. The actual value of current limit is
(I
SENSE
+
– I
SENSE
–
)/IOUT_CAL_GAIN in Amperes.
BASED ON PEAK-TO-PEAK INDUCTOR CURRENT = 40% OF 30A FOR WORST CASE, THESE ARE APPROXIMATES, SO USE GUARDBAND AND CHECK
MFR_PWM_MODE[7] = 1
High Current Range (mV)
~ILPeak (A)
~IOUT (A)
MFR_PWM_MODE[7] = 0
Low Current Range (mV)
~ IL Peak (A)
~ IOUT (A)
17.73
57
51
9.85
32
26
18.86
61
55
10.48
34
28
20.42
66
60
11.34
37
31
21.14
68
62
11.74
38
32
22.27
72
66
12.37
40
34
23.41
76
70
13.01
42
36
24.55
79
73
13.64
44
38
Note: This is the peak of the current waveform. The READ_IOUT command returns the average current. The peak output
current limits are adjusted with temperature based on the MFR_IOUT_CAL_GAIN_TC using the equation:
Peak Current Limit = IOUT_CAL_GAIN • (1 + MFR_IOUT_CAL_GAIN_TC • (READ_TEMPERTURE_1-27.0)).
The LTM4680 automatically convert currents to the appropriate internal bit value.
The I
OUT
range is set with bit 7 of the MFR_PWM_MODE command.
The IOUT_OC_FAULT_LIMIT is ignored during TON_RISE and TOFF_FALL.
If the IOUT_OC_FAULT_LIMIT is exceeded, the device:
• Sets the IOUT bit in the STATUS word
• Sets the IOUT Overcurrent fault bit in the STATUS_IOUT
• Notifies the host by asserting
ALERT
, unless masked
This command has two data bytes and is formatted in Linear_5s_11s format.
