LTC3883 Datasheet, PDF (73/112 Pages) Linear Technology – Single Phase Step-Down DC/DC Controller with Digital Power System Management

LTC3883/LTC3883-1
PMBus Command Details
VOUT_COMMAND
The VOUT_COMMAND consists of two bytes and is used to set the output voltage, in volts.
This command will not be acted on during TON_RISE and TOFF_FALL output sequencing. The VOUT_TRANSITION_RATE
will be used if this command is modified while the output is active and in a steady-state condition.
This command has two data bytes and is formatted in Linear_16u format.
VOUT_MARGIN_LOW
The VOUT_MARGIN_LOW command loads the unit with the voltage to which the output is to be changed, in volts,
when the OPERATION command is set to “Margin Low”. The value must be less than VOUT_COMMAND.
This command will not be acted on during TON_RISE and TOFF_FALL output sequencing. The VOUT_TRANSITION_RATE
will be used if this command is modified while the output is active and in a steady-state condition.
This command has two data bytes and is formatted in Linear_16u format.
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 120ms.
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# status bit in the STATUS_WORD
command should be de-asserted. POWER_GOOD_ON is detected with an A/D read resulting in latency of up to 120ms.
The POWER_GOOD_ON value must be set higher than the POWER_GOOD_OFF value.
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# status bit in the STATUS_WORD
command should be asserted. POWER_GOOD_OFF is detected with an A/D read resulting in latency of up to 120ms.
The POWER_GOOD_OFF value must be set lower than the POWER_GOOD_ON value.
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