MAX8688
Digital Power-Supply Controller/Monitor
with PMBus Interface
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3) Responds as specified by IOUT_OC_FAULT_
RESPONSE bits in the MFR_FAULT_RESPONSE
register.
4) Notifies the host using FLT assertion.
IOUT_OC_WARN_LIMIT (4Ah)
The IOUT_OC_WARN_LIMIT command sets the value of
the output current, in amperes, measured across ISN+
and ISN- that causes an output overcurrent warning.
The 2 data bytes are in DIRECT format. Valid values are
the same as the IOUT_OC_FAULT_LIMIT.
The default IOUT_OC_WARN_LIMIT value is 00h.
In response to the IOUT_OC_WARN_LIMIT being
exceeded, the MAX8688:
1) Sets the OTHER bit in the STATUS_BYTE.
2) Sets the IOUT_OC_WARN bit in the
MFR_FAULT_STATUS register.
3) Notifies the host using FLT assertion.
OT_FAULT_LIMIT (4Fh)
The OT_FAULT_LIMIT command sets the temperature,
in degrees Celsius, of the on-chip temperature sensor
at which an overtemperature fault is detected.
The 2 data bytes are in DIRECT format. Valid values are
from -142.5°C to +395.4°C.
The default OT_FAULT_LIMIT value is 00h.
In response to the OT_FAULT_LIMIT being exceeded,
the MAX8688:
• Sets the TEMPERATURE bit in the STATUS_BYTE.
• Sets the OT_FAULT bit in the MFR_FAULT_STATUS
register.
• Responds as specified by OT_FAULT_RESPONSE
bits in the MFR_FAULT_RESPONSE register.
• Notifies the host using FLT assertion.
OT_WARN_LIMIT (51h)
The OT_WARN_LIMIT command sets the temperature,
in degrees Celsius, of the on-chip temperature sensor
at which an overtemperature warning is detected.
The 2 data bytes are in DIRECT format. Valid values are
the same as the OT_FAULT_LIMIT.
The default OT_WARN_LIMIT value is 00h.
In response to the OT_WARN_LIMIT being exceeded,
the MAX8688:
• Sets the TEMPERATURE bit in the STATUS_BYTE.
• Sets the OT_WARN bit in the MFR_FAULT_STATUS
register.
• Notifies the host through FLT using assertion.
TON_DELAY (60h)
TON_DELAY sets the time, in milliseconds, from when a
start condition is received (a valid OPERATION com-
mand or through A3/ONOFF when enabled) until the
POL output voltage starts to rise. During TON_DELAY,
the POL is disabled (ENOUT deasserted) until
TON_DELAY expires. Also, the undervoltage fault and
warning are masked off during TON_DELAY.
The 2 data bytes are in DIRECT format. Valid values are
from 0 to 3276.7ms.
The default TON_DELAY value is 0ms.
TON_RISE (61h)
The TON_RISE sets the time, in milliseconds, from
when the POL output voltage starts to rise until the volt-
age has entered the regulation band. During
TON_RISE, the voltage, current, and temperature-relat-
ed faults and warnings are masked off. Meanwhile, the
MAX8688 still responds to the PMBus command. If a
TON_RISE parameter results in the DAC outputting an
out-of-range value (valid range 0 to 4090) immediately
during TON_RISE, the CML flag is set and FLT asserts
to issue a warning.
In feedback mode, the MAX8688 leaves the S1 switch
on the DAC open during soft-start. It waits for the
TON_RISE time to expire before adjusting the DAC out-
put to equal the DACOUT feedback and then closes S1.
The 2 data bytes are in DIRECT format. In REFIN mode,
the TON_RISE parameter is a 16-bit value and the valid
values are from 0.01ms to 32.767ms. In FB mode, the
TON_RISE is a 14-bit value and the valid values are
from 0.01ms to 16.383ms (the upper 2 bits are
ignored).
The default TON_RISE value is 0.01ms. Setting any
value less than this minimum value defaults back to
0.01ms.
TOFF_DELAY (64h)
The TOFF_DELAY sets the time, in milliseconds, from
when a STOP condition is received (a soft-off OPERATION
command or through A3/ONOFF when enabled) until the
POL stops transferring energy to the output.
When commanded to turn off immediately through the
OPERATION command, the TOFF_DELAY value is
ignored. When commanded to turn off through
A3/ONOFF (when enabled), the TOFF_DELAY parame-
ter is used.
The 2 data bytes are in DIRECT format. Valid values are
from 0 to 3276.7ms.
The default TOFF_DELAY value is 0ms.
