Datasheet

10
OUT(OV _ req)
V VOUT _ OV _ FAULT _LIMIT 2
-
= ´
TPS40400
SLUS930B –APRIL 2011– REVISED OCTOBER 2011 www.ti.com
Exponent
–15 (dec), fixed.
Mantissa
The upper four bits are fixed at 0.
The lower seven bits are programmable with a default value of 98 (dec)
IOUT_CAL_OFFSET (39h)
The IOUT_CAL_OFFSET is used to compensate for offset errors in the READ_IOUT results and the
IOUT_OC_FAULT_LIMIT and IOUT_OC_WARN_LIMIT thresholds. The units are amps. The default setting is 0
amps. The resolution of the argument for this command is 62.5 mA and the range is +3937.5mA to -4000 mA.
Values written outside of this range alias into the supported range. For example, 1110 0100 0000 0001 has an
expected value of –63.0625 amps, but results in 1110 0111 1111 0001 which is –0.9375 A. This occurs because
the read-only bits are fixed. The Exponent is always –4 and the 5 msb bits of the Mantissa are always equal to
the sign bit. The contents of this register can be stored to non-volatile memory using the STORE_DEFAULT_ALL
or STORE_DEFAULT_CODE commands.
Command IOUT_CAL_OFFSET
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/w r r r r r/w r/w r/w r/w r/w r/w
Function Exponent Mantissa
Default Value 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0
Exponent
–4 (dec), fixed.
Mantissa
MSB is programmable with sign, next 4 bits are sign extend only.
Lower six bits are programmable with a default value of 0 (dec)
VOUT_OV_FAULT_LIMIT (40h)
The VOUT_OV_FAULT_LIMIT command sets the value of the output voltage that causes an output overvoltage
fault. The contents of this register can be stored to non-volatile memory using the STORE_DEFAULT_ALL or
STORE_DEFAULT_CODE commands.
The effective value 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) so the effective overvoltage trip point
requested is:
(19)
The VOUT_OV_FAULT_LIMIT has two data bytes formatted as 2's complement binary integer. The actual values
for the VOUT_ OV_FAULT_LIMIT trip point are set to fixed percentages of nominal V
OUT
. There are four fixed
percentages of the nominal V
OUT
that are supported for overvoltage trip points.
• 108%
• 110%
• 112% (default)
• 115%
For example, for a 1.2V nominal output, VOUT_OV_FAULT_LIMIT can be set to 1.296 V, 1.32 V, 1.344 V or
1.38 V. Values within the supported range is set to the nearest fixed percentage. It is critical that the correct
value be programmed into VOUT_SCALE_LOOP for the correct overvoltage fault trip point to be calculated.
Values outside the supported range results in the corresponding extreme value to be selected. No error
conditions are reported
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