AD5940
Data Sheet
HIGH SPEED TIA CIRCUIT REGISTERS
Table 36. High Speed TIA Registers Summary
Address
Name
Description
Reset
Access
R/W
R/W
0x000020F0
0x000020F8
0x000020FC
HSRTIACON
DE0RESCON
HSTIACON
High speed RTIA configuration
DE0 high speed TIA resistors configuration
High speed TIA configuration
0x0000000F
0x000000FF
0x00000000
R/W
High Speed RTIA Configuration Register—HSRTIACON
Address 0x000020F0, Reset: 0x0000000F, Name: HSRTIACON
This register controls the high speed RTIA, current protection diode, and feedback capacitor
Table 37. Bit Descriptions for HSRTIACON Register
Bits
Bit Name
Settings
Description
Reset Access
[31:13] Reserved
Reserved.
0x0
0x0
R
R/W
[12:5]
CTIACON
Configure capacitor in parallel with RTIA. This capacitor stabilizes the amplifier
loop. When this bit is set, the capacitor is added in parallel with the RTIA
resistor.
0
1
1 pF.
2 pF.
10 4 pF.
100 8 pF.
1000 16 pF.
10000 2 pF.
100000 Not used.
1000000 Not used.
4
TIASW6CON
RTIACON
SW6 switch control. Use the SW6 switch to select whether or not to use the diode
in parallel with RTIA.
SW6 off, diode is not in parallel with RTIA.
SW6 on, diode is in parallel with RTIA.
0x0
0xF
R/W
R/W
0
1
[3:0]
Configure general RTIA value. To use this RTIA resistor, close the T9 switch (SWCON,
Bit 17) and open the T10 switch (SWCON, Bit 17).
0000 RTIA = 200 Ω.
0001 RTIA = 1 kΩ.
0010 RTIA = 5 kΩ.
0011 RTIA = 10 kΩ.
0100 RTIA = 20 kΩ.
0101 RTIA = 40 kΩ.
0110 RTIA = 80 kΩ.
0111 RTIA = 160 kΩ.
1000 to 1111 RTIA is open.
DE0 High Speed TIA Resistors Configuration Register—DE0RESCON
Address 0x000020F8, Reset: 0x000000FF, Name: DE0RESCON
Table 38. Bit Descriptions for DE0RESCON Register
Bits
[31:8] Reserved
[7:0] DE0RCON
Bit Name
Settings Description
Reset Access
Reserved.
0x0
R
RLOAD_DE0 and RTIA_DE0 setting. To use this RLOAD_DE0 and RTIA_DE0 setting, open the T9
0xFF
R/W
switch, close the T10 switch, and set the RTIA resistor values (see Table 35).
Rev. 0 | Page 48 of 130
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