Datasheet

10
OUT(offst)
V VOUT _ TRIM 2
-
= ´
( )
( )
10
OUT MH
V VOUT _ MARGIN _ HIGH VOUT _ TRIM 2
-
= + ´
TPS40400
www.ti.com SLUS930B –APRIL 2011– REVISED OCTOBER 2011
Mode:
Value fixed at 000, linear mode.
Exponent
Value fixed at 11011, Exponent for Linear mode values is –10.
VOUT_TRIM (22h)
The VOUT_TRIM command is used to apply a fixed offset voltage to the output voltage command value. It is
most typically use by the end user to trim the output voltage at the time the PMBus device is assembled into the
end user system. It is vital that the VOUT_SCALE_LOOP comand is set correctly in order to obtaining correct
results. The contents of this register can be stored to non-volatile memory using the STORE_DEFAULT_ALL or
STORE_DEFAULT_CODE commands.
The effect of this command is determined by the settings of the VOUT_MODE command. In this device, the
VOUT_MODE is fixed to Linear with an exponent of –10 (decimal).
(15)
The maximum value of V
OUT(offst)
is ±25% of nominal VOUT. Nominal V
OUT
is set by external resistors and the
600 mV error amplifier reference. The valid range in 2s complement for this command is –4000h to 3FFF. The
high order two bits of the high byte must both be either 0 or 1. They cannot have different values. If a value
outside of the ±25% is given with this command, the TPS40400 sets the output voltage to the upper or lower limit
depending on the direction of the setting, assert SMBALRT, set the CML bit in STATUS_BYTE and the invalid
data bit STATUS_CML.
Command VOUT_TRIM
Format Linear, two’s complement binary
Bit Position 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
Access r/w r r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w r/w
Function High Byte Low Byte
Default
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Value
VOUT_MARGIN_HIGH (25h)
The VOUT_MARGIN_HIGH command sets the target voltage which the output changes to when the
OPERATION command is set to "Margin High". The contents of this register can be stored to non-volatile
memory using the STORE_DEFAULT_ALL or STORE_DEFAULT_CODE commands.
The effect of this command is determined by the settings of the VOUT_MODE command. In this device, the
VOUT_MODE is fixed to Linear with an exponent of –10 (decimal). The actual output voltage commanded by a
margin high command can be found by:
(16)
The maximum margin range is ±25% of nominal VOUT. Nominal VOUT is set by external resistors and a 600 mV
error amplifier reference and does not include the offset generated by VOUT_TRIM. It is critical that the correct
value be programmed into VOUT_SCALE_LOOP for the correct margin value to be calculated. Error checking is
not performed when the VOUT_MARGIN_HIGH command is issued. The error checking is done when the
OPERATION command is issued calling for a margin high state. At that time, values outside the ±25% range is
treated as invalid data and causes the set the CML bit in the STATUS_BYTE and the invalid data (ivd) bit in the
STATUS_CML registers. The output voltage is then set to to the upper or lower limit depending on the direction
of the setting. The device state can be restored to power up defaults by issuing either the
RESTORE_DEFAULT_ALL or RESTORE_DEFAULT_CODE commands.
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