SML2108 View Datasheet(PDF) - Summit Microelectronics
Part Name
Description
MFG CO.
'SML2108' PDF : 21 Pages View PDF
SML2108
PRELIMINARY
ADC SCALING AND OFFSET
The ADC can be customized to monitor a particular range
of bias current by programming Register 0. Bits 3 and 2
control the scaling of the ADC while bits 1 and 0 control the
ADC offset. The four graphs (Figures 4, 5, 6, & 7) illustrate
the ADC scale values, according to the two bit code. In
each Graph the curves are differentiated by the ADC offset
values. Note: if using IBIASP with the maximum current
option set to 10 mA, divide the x-axis value by 10 (i.e., 75
= 7.5, etc.).
These combinations of scales and offsets allow the reso-
lution to be maximized over a given range of current. For
example, if the bias current is known to be in the range of
30mA to 70mA the choice would be the Half scale graph
(code 10BIN) and the ¼ offset curve (code 01BIN) to
maximize the resolution of the ADC.
Note that these graphs assume a full scale bias current of
100mA. When the ADC is configured to receive input from
the EXT TEMP pin full scale current becomes 390.6µA,
which limits the internal 1/256 scale factor between bias
current and the ADC input current.
255
224
Offset
00
192
01
10
160
11
128
96
64
32
0
0 10 20 30 40 50 60 70 80 90 100
IBIAS (mA)
2053 Fig04
Figure 4. Full Scale (code 11BIN) with Offset
255
224
Offset
00
192 01
10
160 11
128
96
64
32
0
0 10 20 30 40 50 60 70 80 90 100
IBIAS (mA)
2053 Fig05
Figure 5. Half Scale (code 10BIN) with Offset
255
255
224
224
192
192
160
Offset
00
128
01
10
96
11
160
Offset
00
128
01
10
96
11
64
64
32
32
0
0 10 20 30 40 50 60 70 80 90 100
IBIAS (mA)
2053 Fig06
0
0 10 20 30 40 50 60 70 80 90 100
IBIAS (mA)
2053 Fig07
Figure 6. Quarter Scale (code 01 ) with Offset
BIN
Figure 7. Tenth Scale (code 00 ) with Offset
BIN
2053 2.2 11/07/00
SUMMIT MICROELECTRONICS, Inc.
10
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