High-Side Current-Sense and Internal 1°C Temperature Monitor
Datasheet
Table 5.30 VSENSE Data Format (continued)
VSENSE
BINARY
HEX (AS READ BY REGISTERS)
+1 LSB
+2 LSB
0000_0000_0001
0000_0000_0010
0111_1111_1111
00_1h
00_2h
7F_Fh
Plus Full Scale
5.19 Source Voltage Registers
Table 5.31 Source Voltage Registers
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
58h
R
VSOURCE
High Byte
12
6
3
1.5
0.75
0.375
0.1875
0.0938
00h
59h
R
VSOURCE
low Byte
0.0469
0.0234
0.0117
-
-
-
-
-
00h
The Source Voltage registers store the voltage measured at the SENSE+ pin (see Section 4.1.2,
"Voltage Measurement") as a digital value, VSOURCE, consisting of a high byte and low byte with five
of its LSBs always zero.
The measured voltage is determined by summing the bit weights of each bit set. For example, if VBUS
was 7.4V, the Source Voltage registers would read 0100_1110 for the high byte and 1100_0000b for
the low byte corresponding to 6V + 0.75V + 0.375V + 0.1875V + 0.0469V + 0.0234V = 7.383V.
The bit weightings are assigned for human interpretation. They should be disregarded when translating
the information via a computing system as shown in Section 4.1.2, "Voltage Measurement".
The Source Voltage registers cannot support negative values, and all values less than 0V will be
recorded as 0V.
5.20 Power Ratio Registers
Table 5.32 Power Ratio Registers
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
5Bh
5Ch
R
Power Ratio
High Byte
32768
16384
8192
4096
2048
1024
512
256
00h
R
Power Ratio
Low Byte
128
64
32
16
8
4
2
1
00h
The Power Ratio registers store a power factor value that is used to determine the final average power
delivered to the system (see Section 4.1.3, "Power Calculation"). The power factor value is the result
of the multiplication of the VSENSE reading and the VSOURCE reading values shifted to a 16-bit number.
It represents the ratio of delivered power with respect to maximum power.
SMSC EMC1701
Revision 1.2 (09-27-10)
DATA4S3HEET
SMSC [ SMSC CORPORATION ]
