Datasheet

1
1.5
2
2.5
3
10n 100n 1 10 100 1m 10mm m m
Input Current (A)
Output Voltage (V)
Uncompensated Output
Compensated Output
Verifying Results www.ti.com
5 Verifying Results
Making measurements on the LOG114EVM is fast and easy. Connect a digital voltmeter or oscilloscope to
the terminal of interest and record the results. Included with the graph of measured results is a table of
results for common values of input currents. In Figure 13, two curves are shown. Both curves use a
resistor input and V
OUT
is recorded as a function of input current. The compensated (red) curve connects
the resistor as shown in Figure 11 and uses the high-current linearity correction circuitry. The
uncompensated curve (blue) uses the resistor connected to I
1
and V
REF
as shown in Figure 10.
Figure 13. LOG114EVM Measured Results
Table 1 lists several typical results obtained with various input voltages.
Table 1. LOG114EVM Typical Results
Uncompensated Compensated
Input V
LOGOUT
(V) V
OUT
(V) V
LOGOUT
(V) V
OUT
(V)
10 nA 1.36 1.15 1.36 1.15
100 nA 1.74 1.38 1.74 1.38
1 μA 2.11 1.60 2.11 1.60
10 μA 2.49 1.83 2.49 1.83
100 μA 2.87 2.06 2.87 2.06
1 mA 3.29 2.31 3.29 2.30
10 mA 4.11 2.82 4.11 2.67
12
LOG114EVM User Guide SBOU110– September 2011
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