Datasheet
Exponent
OUT
I Mantissa 2= ´
Exponent
IN
V Mantissa 2= ´
TPS40400
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SLUS930B –APRIL 2011– REVISED OCTOBER 2011
READ_IOUT (8Ch)
The READ_IOUT commands returns two bytes of data in the linear data format that represent the output current
of the controller. The output current is sensed at the ISNS+ and ISNS– pins. The data format is as follows:
Command READ_IOUT
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 r r r r r r r r r r r r r r r
Function Exponent Mantissa
Default Value 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0
The output current is scaled before it reaches the internal analog to digital converter so that resolution of the
output current read is 62.5 mA, though resolution may be less depending on the setting of IOUT_CAL_GAIN.
The maximum value that can be reported is 64 A. It is mandatory that the IOUT_CAL_GAIN and
IOUT_CAL_OFFSET parameters are sset correctly in order to obtain accurate results. The output current can be
found by using Equation 27.
(27)
Exponent
Fixed at -4.
Mantissa
The lower 10 bits are the result of the ADC conversion of the input voltage. The 11
th
bit is fixed at 0 because only
positive numbers are considered valid.
PMBUS_REVISION (98h)
The PMBUS_REVISION command returns a single, unsigned binary byte that indicates that the TPS40400 is
compliant with the 1.1 revision of the PMBus specification.
Command PMBUS_REVISION
Format Unsigned binary
Bit Position 7 6 5 4 3 2 1 0
Access r r r r r r r r
Default Value 0 0 0 1 0 0 0 1
MFR_VIN_MIN (A0h)
The MFR_VIN_MIN command returns a two-byte linear formatted result that indicates the minimum voltage from
which the TPS40400 is able to convert power. The data is formatted as follows:
Command MFR_VIN_MIN
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 r r r r r r r r r r r r r r r
Function Exponent Mantissa
Default Value 1 1 1 1 0 0 0 0 0 0 0 0 1 1 0 0
The minimum input voltage can be found using Equation 28.
(28)
This equates to 3 V when evaluated with the default values. The TPS40400 begins to convert power at a
minimum input of 2.75-V.
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