lm25066apsqx National Semiconductor Corporation, lm25066apsqx Datasheet - Page 40

• Manufacturer Part Number: lm25066apsqx
• Description: Lm25066a System Power Management And Protection Ic With Pmbus
• Manufacturer: National Semiconductor Corporation

www.national.com
READ_VOUT, READ_AVG_VOUT
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 bi-
nary 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
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 rela-
tionship:
* The coefficients relating to current/power measurements and warning thresholds shown in Table 41 are normalized to a sense resistor (R
general, the current/power coefficients can be calculated using the relationships shown in Table 42.
*READ_PIN, READ_AVG_PIN,
*READ_PIN, READ_AVG_PIN,
Byte
READ_VIN, READ_AVG_VIN
MFR_PIN_OP_WARN_LIMIT
MFR_PIN_OP_WARN_LIMIT
MFR_IIN_OC_WARN_LIMIT
MFR_IIN_OC_WARN_LIMIT
*READ_IN, READ_AVG_IN
*READ_IN, READ_AVG_IN
READ_TEMPERATURE_1
1
2
VOUT_UV_WARN_LIMIT
VIN_OV_WARN_LIMIT
VIN_UV_WARN_LIMIT
READ_PEAK_PIN
READ_PEAK_PIN
OT_FAULT_LIMIT
OT_WARN_LIMIT
READ_VAUX
Commands
Bit_7
B7
0
Bit_6
TABLE 41. Telemetry and Warning Conversion Coefficients
B6
0
TABLE 40. Telemetry and Warning Word Format
Condition
CL = GND
CL = GND
CL = VDD
CL = VDD
Bit_5
B5
0
Bit_4
B4
40
0
II). The organization of the bits in the telemetry or warning
word is shown in Table 40, where Bit_11 is the most signifi-
cant 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 ex-
ception of temperature. The decimal equivalent value of the
temperature word ranges from 0 to 65535.
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.
DIRECT
DIRECT
DIRECT
DIRECT
DIRECT
DIRECT
DIRECT
DIRECT
Format
Bit_11
Bit_3
B3
Data Bytes
Number of
2
2
2
2
2
2
2
2
Bit_10
Bit_2
B2
22070
22070
35330
13661
16000
6852
736
369
m
Bit_1
Bit_9
B1
-1800
-1800
-5200
-3100
-3300
-1900
-150
b
0
S
) value of 1mΩ. In
-2
-2
-2
-2
-2
-2
-3
R
0
Bit_0
Bit_8
B0
Units
°C
W
W
V
V
V
A
A