Datasheet

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last update
November 30, 2010
reference
smtutin
page
12/27
6.2 Mode 1. C23: 3 capacitors 0-2pF 
In this mode, 3 capacitors in the range of 0 - 2 pF with one common electrode can be measured. In order to understand what
this means in practical terms, please refer to the note in paragraph 5.5. The difference with mode C25 is that one cycle
consists of only 3 phases. The connection of the capacitors is shown in Fig 6 where C
EA
and C
FA
are omitted now. The measured
capacitors during each phase are listed in Table 7. The specifications are listed 


6.3 Mode 2. C12: 5 capacitors 0-12pF
In this mode, 5 capacitors in the range of 0 - 12 pF with one common electrode can be measured. In order to understand what
this means in practical terms, please refer to the note in paragraph 5.5. The connection of the capacitors to the UTI is
shown in Fig.6 . The maximum value of the capacitance C
iA
(i is B, C, D or E) is 12 pF. The number of phases is 5. The
specifications are listed in Table 8. The measured capacitors during each phase are indicated in Table 5 . The main difference
with mode 0 is that the maximum measurable capacitance is 12 pF.
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The remaining offset capacitance is caused by the parasitics between bonding wires, bonding pads and IC pins. When this
offset is too large, one should use the mode CMUX. In this case, an external multiplexer is used and offset can be as low as 20
×10
-6
pF.
Phase Measured
capacitor
Output periods
1 C
BA
+C
off
T
BA
=NK
1
(C
BA
+C
off
)
2 C
CA
+C
off
T
CA
=NK
1
(C
CA
+C
off
)
3 C
DA
+C
off
T
DA
=NK
1
(C
DA
+C
off
)
4 C
EA
+C
off
T
EA
=NK
1
(C
EA
+C
off
)
5 C
FA
+C
off
T
FA
=NK
1
(C
FA
+C
off
)
Table 7. Measured capacitors during phase of mode C23
Parameter Typical value
K
1
1,7 s/pF
C
0ff
12 pF
Max cap value (C
xa
) 12 pF
Linearity 13 bits
Resolution (SF=0) 14 bits
Remaining offset < 15 x10
-3
pF
Table 8. specifications of the C12 mode