Datasheet

LTC3880/LTC3880-1
73
3880fc
For more information www.linear.com/LTC3880
PMBus COMMAND DETAILS
VOUT_UV_WARN_LIMIT
The VOUT_UV_ WARN_LIMIT command reads the value of the output voltage measured at the sense pins, in volts,
which causes an output voltage low warning.
In response to the VOUT_UV_WARN_LIMIT being exceeded, the device:
• Sets the NONE_OF_THE_ABOVE bit in the STATUS_BYTE
• Sets the VOUT bit in the STATUS_WORD
• Sets the VOUT Undervoltage Warning bit in the STATUS_VOUT command
• Notifies the host by asserting ALERT pin
This condition is detected by the ADC so the response time may be up to 100ms.
This command has two data bytes and is formatted in Linear_16u format.
VOUT_UV_FAULT_LIMIT
The VOUT_UV_FAULT_LIMIT command reads the value of the output voltage measured at the sense pins, in volts,
which causes an output undervoltage fault.
This command has two data bytes and is formatted in Linear_16u format.
POWER_GOOD_ON
The POWER_GOOD_ON command sets the output voltage at which the POWER_GOOD signal should be asserted.
POWER_GOOD_ON is detected with an A/D read resulting in latency of up to 100ms.
This command has two data bytes and is formatted in Linear_16u format.
POWER_GOOD_OFF
The POWER_GOOD_OFF command sets the output voltage at which the POWER_GOOD signal should be negated.
POWER_GOOD_OFF is detected with an A/D read resulting in latency of up to 100ms. At initial power up the output of
this pin will be high even though the state should be low. If the proper state at power-up is required, place a Schottky
diode between RUN and GPIO. The Anode must be tied to GPIO and the Cathode to RUN.
The POWER_GOOD_ON status is masked from initiating an ALERT. The POWER_GOOD status bit in the STATUS_WORD
command is always reflective of VOUT wrt. the POWER_GOOD threshold.
This command has two data bytes and is formatted in Linear_16u format.
MFR_VOUT_MAX
The MFR_VOUT_MAX command is the maximum output voltage in volts for each channel including VOUT_OV_
FAULT_LIMIT. If the output voltages are set to high range (Bits 5 and 6 of MFR_PWM_CONFIG_LTC3880 set to a 0)
MFR_VOUT_MAX for channel 0 is 4.096V and MFR_VOUT_MAX for channel 1 is 5.5V. If the output voltages are set to
low range (Bits 5 and 6 of MFR_PWM_CONFIG_LTC3880 set to a 1) the MFR_VOUT_MAX for both channels is 2.75V.
Entering VOUT_COMMAND values greater than this will result in a CML fault and the output voltage setting will be
clamped to the maximum level.
This read-only command has 2 data bytes and is formatted in Linear_16u format.