AD5940
Data Sheet
Bits
Bit Name
Settings
Description
Reset Access
1
SW1
SW1 switch control, active high.
Opens switch.
Closes switch.
0x0
R/W
0
1
0
SW0
SW0 switch control, active high.
Opens switch.
Closes switch.
0x0
R/W
0
1
Low Power TIA Control Bits, Channel 0 Register—LPTIACON0
Address 0x000020EC, Reset: 0x00000003, Name: LPTIACON0
Table 23. Bit Descriptions for LPTIACON0 Register
Bits
Bit Name Settings Description
Reset Access
[31:16] Reserved
[15:13] TIARF
Reserved.
0x0
R
R/W
These bits set the low-pass filter resistor (RLPF) and configure the low power TIA output 0x0
low-pass filter cutoff frequency.
0
1
Disconnects the TIA output from the low-pass filter pin (LPF0), which is useful for
diagnostics where a fast response is required from the ADC. This setting disconnects
the low power TIA output from the low-pass filter capacitor.
Bypass resistor; 0 Ω option.
10 20 kΩ.
11 100 kΩ.
100 200 kΩ.
101 400 kΩ.
110 600 kΩ.
111 1 MΩ; recommended value for optimal dc current measurement performance. This
setting is the lowest cutoff frequency setting for the low-pass filter.
[12:10] TIARL
These bits set RLOAD
.
0x0
R/W
0
1
0 Ω.
10 Ω.
10 30 Ω.
11 50 Ω.
100 100 Ω.
101 1.6 kΩ; RTIA must be ≥ 2 kΩ.
110 3.1 kΩ; RTIA must be ≥ 4 kΩ.
111 3.6 kΩ; RTIA must be ≥ 4 kΩ.
These bits set the RTIA.
[9:5]
TIAGAIN
0x0
R/W
0
1
Disconnects the RTIA.
200 Ω. The RTIA is combination of RLOAD and a fixed series 110 Ω. Assumes RLOAD = 10 Ω.
Set by the TIARL bits. RTIA = 100 Ω − RLOAD + 110 Ω. The fixed overall RTIA = 200 Ω.
10 1 kΩ. If RLOAD ≤ 100 Ω, RTIA = (100 Ω − RLOAD) + 1 kΩ. If RLOAD > 100 Ω, RTIA = 1 kΩ −
(RLOAD − 100 Ω).
11 2 kΩ. If RLOAD ≤ 100 Ω, RTIA = (100 Ω − RLOAD) + 2 kΩ. If RLOAD > 100 Ω. RTIA = 2 kΩ −
(RLOAD − 100 Ω).
100 3 kΩ. If RLOAD ≤ 100 Ω, RTIA = (100 Ω − RLOAD) + 3 kΩ. If RLOAD > 100 Ω. RTIA = 3 kΩ −
(RLOAD − 100 Ω).
101 4 kΩ. If RLOAD ≤ 100 Ω, RTIA = (100 Ω − RLOAD) + 4 kΩ. If RLOAD > 100 Ω. RTIA = 4 kΩ −
(RLOAD − 100 Ω).
110 6 kΩ. If RLOAD ≤ 100 Ω, RTIA = (100 Ω − RLOAD) + 6 kΩ. If RLOAD > 100 Ω. RTIA = 6 kΩ −
(RLOAD − 100 Ω).
111 8 kΩ. If RLOAD ≤ 100 Ω, RTIA = (100 Ω − RLOAD) + 8 kΩ. If RLOAD > 100 Ω. RTIA = 8 kΩ −
(RLOAD − 100 Ω).
1000 10 kΩ. If RLOAD ≤ 100 Ω, RTIA = (100 Ω − RLOAD) + 10 kΩ. If RLOAD > 100 Ω. RTIA
10 kΩ − (RLOAD − 100 Ω).
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Rev. 0 | Page 38 of 130
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