# Simple Low-Power DAC

## Functional Description

The SDAC (Simple Digital-to-Analog Converter) is a buffer with selectable gain (G=1 or G=2), which buffers the WEDAC voltage generated in the bandgap reference. Its output can be used as reference or sensor supply on the PCB; to do this, the user needs to configure GPIO[7] as GPIO_MODE_DISABLE, and route the output through this AIO. Current drive is limited, because the AIO has a series resistance of 500 Ω and the signal is multiplexed with other analog signals. If a higher current drive is needed, an external buffer has to be used.

To configure the SDAC as output,

1. Set the GPIO[7] IO mode to disabled.
2. Set the ACS_SDAC_CFG_SDAC_TO_GPIO7 field in the ACS_SDAC_CFG register (see Simple Low-Power DAC).

The SDAC output can also be connected internally to the SAR-ADC reference input using the SENSOR_SAR_CFG_SAR_IN_P or SENSOR_SAR_CFG_SAR_IN_N fields in the SENSOR_SAR_CFG register. This provides a low impedance buffer to the WEDAC reference voltage for the SAR-ADC.

The "Simple DAC Electrical Specifications" table shows the simple DAC’s electrical specifications.

Table: Simple DAC Electrical Specifications
Voltage Type | Voltage Range
--- | ---
Input voltage VDDA rail | Common input mode range: 0 V to +2.6 V
Input offset voltage with regard to input reference | -15 mV to +15 mV
Output voltage | 0.1 V to VDDA-0.2 V NOTE: Cannot exceed VDDO when connected to GPIO.
Output current | Maximum 10 μA
Voltage gains | Can be set to 1 (buffer) or 2 (amplifier) Gain error maximum: 2%
Current consumption | Maximum 5 μA

For more information on the simple DAC’s electrical specifications, see the RSL15 Datasheet.

For registers, see SDAC Registers.