Datasheet

10
OUT(UV _ req)
V VOUT _ UV _ FAULT _ LIMIT 2
-
= ´
TPS40400
SLUS930B –APRIL 2011– REVISED OCTOBER 2011 www.ti.com
VOUT_UV_FAULT_LIMIT (44h)
The VOUT_UV_FAULT_LIMIT command sets the value of the output voltage that causes an output undervoltage
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:
(20)
The VOUT_UV_FAULT_LIMIT has two data bytes formatted as two's complement binary integer. The actual
values for VOUT_ UV_FAULT_LIMIT trip point are set to fixed percentages of nominal VOUT. There are four
fixed percentages of V
OUT
that are supported for overvoltage trip points.
• 92%
• 90%
• 88% (default)
• 85%
For example, for a 1.2 V nominal output, VOUT_UV_FAULT_LIMIT can be set to 1.104 V, 1.08 V, 1.056 V or
1.02 V. Values within the supported range are 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.
The VOUT_UV_FAULT_LIMIT command has two bytes formatted as a two’s compliment binary integer:
Command VOUT_UV_FAULT_LIMIT
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/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 r/w
Function High Byte Low Byte
Default Value 0 0 0 0 0 1 0 0 1 0 0 0 1 1 1 1
VOUT_UV_FAULT_RESPONSE (45h)
The VOUT_UV_FAULT_RESPONSE command instructs the device on what action to take in response to a
VOUT_UV_FAULT_LIMIT fault. The device also:
• Sets the VOUT bit in the STATUS_WORD
• Sets the VOUT UV Fault bit in the STATUS_VOUT register, and
• Notifies the host via SMBALRT pin
The contents of this register can be stored to non-volatile memory using the STORE_DEFAULT_ALL or
STORE_DEFAULT_CODE commands.
A one-byte unsigned binary data word is used with this command:
Command VOUT_UV_FAULT_RESPONSE
Format Unsigned binary
Bit Position 7 6 5 4 3 2 1 0
Access r/w r/w r/w r/w r/w r r r
Function RSP[1] RSP[0] RS[2] RS[1] RS[0] X X X
Default Value 0 0 0 0 0 1 0 0
RSP[1:0]
Output voltage undervoltage response
00: The device continues operation without interruption.
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