SLASEA3D December 2016 – December 2023 DAC38RF80 , DAC38RF83 , DAC38RF84 , DAC38RF85 , DAC38RF90 , DAC38RF93
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The DAC38RFxx uses a bandgap reference and control amplifier for biasing the full-scale output current. The DAC full scale output current is set by a combination of the fixed current through the external resistor RBIAS (connected to pin BIASJ) and current from course trim current sources:

The bias current IBIAS through resistor RBIAS is defined by the on-chip bandgap reference voltage VBG (nominally 0.9 V) and control amplifier. For normal operation, it is recommended that RBIAS is set to 3.6 kΩ for a fixed current through RBIAS of 250 µA. This current is scaled 128x internally, giving:

The course trim current sources are configured through SPI register field DACFS in register DACFS (7.5.72),as follows:

From the discussion above, the DAC full scale output current can be configured from 40 mA (DACFS[3:0] = 1111) down to 10 mA (DACFS[3:0] = 0000). In addition to the full scale signal current set by SPI register DACFS (7.5.72), an extra DC bias current is required to set the operating point of the output current sources(Table 7-41).
| DACFS (7.5.72) | Signal current (mA) | Total bias current (mA)(1) |
|---|---|---|
| 0 | 10 | 1 |
| 1 | 12 | 1 |
| 2 | 14 | 2 |
| 3 | 16 | 2 |
| 4 | 18 | 3 |
| 5 | 20 | 3 |
| 6 | 22 | 4 |
| 7 | 24 | 5 |
| 8 | 26 | 5 |
| 9 | 28 | 6 |
| 10 | 30 | 6 |
| 11 | 32 | 7 |
| 12 | 34 | 7 |
| 13 | 36 | 8 |
| 14 | 38 | 8 |
| 15 | 40 | 9 |
An external decoupling capacitor CEXT of 0.1 μF should be connected externally to terminal EXTIO for compensation. RBIAS of 3.6 kΩ is recommended for setting the full-scale output current.