UG-1262
Rev. B | Page 150 of 312
USE CASE CONFIGURATIONS
The
is primarily designed for controlling and measuring electrochemical sensors. This section gives suggested setup details
for the main use cases of the
with an electrochemical sensor.
HIBERNATE MODE WHILE MAINTAINING A DC BIAS TO THE SENSOR
In this mode, the digital die and analog die are in hibernate mode.
Digital Die
On the digital die, the low power LDO regulator and low power, 32 kHz oscillator are active. This LDO regulator and oscillator support
retention of the SRAM contents and maintains the configuration of the digital input/output pins while minimizing current consumption.
Analog Die
On the analog die, the low power LDO regulator and low power, 32 kHz oscillator are active. The low power reference, low power DAC,
low power potentiostat amplifier, and low power TIAs are also active to maintain a dc bias voltage to an external sensor. The switches
connecting the low power amplifiers to the external sensor are also unaffected when entering or exiting this mode. For code examples on
how to enter and exit hibernate mode, see the Hibernate Mode, Mode 2 section.
To maintain a bias voltage to an electrochemical sensor, the recommended analog die configuration setting for the low power
potentiostat amplifier and low power TIA is LPTIASWx = 0x302C. Figure 38 shows how the switches are configured in the low power
potentiostat amplifier with this value.
Minimize leakage in the unused switches in the switch matrix by tying an unused pin to the internal 1.8 V digital LDO regulator rail.
Tying the unused pin also ties the excitation amplifier P, N, and D nodes to a fixed level. See the PL, PL2, NL2, and NL switches in Figure 37 to
understand which signal paths must be tied to 1.8 V to minimize leakage current effects. To close these switches, use the following code:
SWCON &= 0xEFFFF; // Clear SWCON[16] to allow access to NSWFULLCON/PSWFULLCON
NSWFULLCON |= 0xC00; // Close NL2 and NL switches
PSWFULLCON |= 0x6000; // Close PL2 and PL switches
SWCON |= 0x10000; // Set SWCON[16] to update switches