Texas Instruments Evaluation Board for the LM25066I LM25066I-EVM/NOPB LM25066I-EVM/NOPB Datenbogen
Produktcode
LM25066I-EVM/NOPB
X =
1
m
(Y x 10
-R
- b)
SNVS824C – JUNE 2012 – REVISED MARCH 2013
Reading and Writing Telemetry Data and Warning Thresholds
All measured telemetry data and user programmed warning thresholds are communicated in 12 bit two’s
compliment binary numbers read/written in 2 byte increments conforming to the Direct format as described in
section 8.3.3 of the PMBus™ Power System Management Protocol Specification 1.1 (Part II). The organization
of the bits in the telemetry or warning word is shown in
compliment binary numbers read/written in 2 byte increments conforming to the Direct format as described in
section 8.3.3 of the PMBus™ Power System Management Protocol Specification 1.1 (Part II). The organization
of the bits in the telemetry or warning word is shown in
, where Bit_11 is the most significant bit (MSB)
and Bit_0 is the least significant bit (LSB). The decimal equivalent of all warning and telemetry words are
constrained to be within the range of 0 to 4095, with the exception of temperature. The decimal equivalent value
of the temperature word ranges from 0 to 65535.
constrained to be within the range of 0 to 4095, with the exception of temperature. The decimal equivalent value
of the temperature word ranges from 0 to 65535.
Table 43. Telemetry and Warning Word Format
Byte
B7
B6
B5
B4
B3
B2
B1
B0
1
Bit_7
Bit_6
Bit_5
Bit_4
Bit_3
Bit_2
Bit_1
Bit_0
2
0
0
0
0
Bit_11
Bit_10
Bit_9
Bit_8
Conversion from direct format to real world dimensions of current, voltage, power, and temperature is
accomplished by determining appropriate coefficients as described in section 7.2.1 of the PMBus™ Power
System Management Protocol Specification 1.1 (Part II). According to this specification, the host system converts
the values received into a reading of volts, amperes, watts, or other units using the following relationship:
accomplished by determining appropriate coefficients as described in section 7.2.1 of the PMBus™ Power
System Management Protocol Specification 1.1 (Part II). According to this specification, the host system converts
the values received into a reading of volts, amperes, watts, or other units using the following relationship:
(38)
where:
X: the calculated "real world" value (volts, amps, watt, etc.)
m: the slope coefficient
Y: a two byte two's complement integer received from device
b: the offset, a two byte two's complement integer
R: the exponent, a one byte two's complement integer
R is only necessary in systems where m is required to be an integer (for example, where m may be stored in a
register in an integrated circuit). In those cases, R only needs to be large enough to yield the desired accuracy.
register in an integrated circuit). In those cases, R only needs to be large enough to yield the desired accuracy.
Table 44. Current, Power and Warning Conversion Coefficients (R
S
in m
Ω
)
Commands
Condition
Format
Number of
m
b
R
Unit
Data Bytes
READ_VIN, READ_AVG_VIN
DIRECT
2
22070
-1800
-2
V
VIN_OV_WARN_LIMIT
VIN_UV_WARN_LIMIT
READ_VOUT, READ_AVG_VOUT
DIRECT
2
22070
-1800
-2
V
VOUT_UV_WARN_LIMIT
READ_VAUX
DIRECT
2
3546
-3
0
V
READ_IIN, READ_AVG_IIN
CL = GND
DIRECT
2
13661 x R
S
-5200
-2
A
MFR_IIN_OC_WARN_LIMIT
READ_IIN, READ_AVG_IIN
CL = VDD
DIRECT
2
6854 x R
S
-3100
-2
A
MFR_IIN_OC_WARN_LIMIT
READ_PIN, READ_AVG_PIN,
CL = GND
DIRECT
2
736 x R
S
-3300
-2
W
READ_PIN_PEAK
MFR_PIN_OP_WARN_LIMIT
READ_PIN, READ_AVG_PIN,
CL = VDD
DIRECT
2
369 x R
S
-1900
-2
W
READ_PIN_PEAK
MFR_PIN_OP_WARN_LIMIT
READ_TEMPERATURE_1
DIRECT
2
16000
0
-3
°C
OT_WARN_LIMIT
OT_FAULT_LIMIT
READ_PIN, READ_AVG_PIN,
CL = VDD
DIRECT
2
369 x R
S
-1900
-2
W
READ_PIN_PEAK
MFR_PIN_OP_WARN_LIMIT
48
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