Datasheet

AD7747
Rev. 0 | Page 17 of 28
EXC SETUP REGISTER
Address Pointer 0x09, Default Value 0x03
Capacitive channel excitation setup.
Table 15. EXC Setup Bit Map
Bit Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Mnemonic – – – – EXCDAC EXCEN EXCLVL1 EXCLVL0
Default 0 0 0 0 0 0 1 1
Table 16.
Bit Mnemonic Description
7 to 4 – These bits must be 0 for proper operation.
3 EXCDAC CAPDAC excitation. This bit must be set to 1 for the proper capacitive channel operation.
2 EXCEN CIN and AC SHLD excitation. This bit must be set to 1 for the proper capacitive channel operation.
Excitation Voltage Level. Must be set to ±V
DD
× 3/8 to allow operation for specified performance.
EXCLVL1 EXCLVL0 Voltage on Cap EXC Low Level EXC High Level
0 0 ±V
DD
/8 V
DD
× 3/8 V
DD
× 5/8
0 1 ±V
DD
/4 V
DD
× 1/4 V
DD
× 3/4
1 0 ±V
DD
× 3/8 V
DD
× 1/8 V
DD
× 7/8
1
0
EXCLVL1,
EXCLVL0
1 1 ±V
DD
/2 0 V
DD