This circuit is a multichannel DAC configuration with different output spans on groups of channels. It utilizes the AD5360 to provide 16 DAC channels with 16 bits of resolution. The AD5360 is configured to have eight channels with an output span of ±10 V and eight channels with an output span of ±5 V.
The AD5360 is a 16-channel, 16-bit DAC available both in 56-lead LFCSP and 52-lead LQFP packages. The AD5360 has two reference input pins. VREF0 is the reference pin for DAC channels VOUT0 to VOUT7. VREF1 is the reference pin for DAC channels VOUT8 to VOUT15.
Figure 1 shows a typical configuration for the AD5360 using two external references. The nominal output span for the AD5360 is four times the reference voltage, with the mid-scale point at 0 V. The ADR431 and ADR421 are low noise precision 2.5 V references. The ADR435 is a low noise precision 5 V reference. When connected as shown in Figure 1, the AD5360 will have an output span of ±5 V on VOUT0 to VOUT7 and an output span of ±10 V on VOUT8 to VOUT15. The AD5360 has two offset DAC registers, which allow the mid-scale point of the span to be altered within the limits of part functionality and headroom.
The circuit must be constructed on a multilayer PC board with a large area ground plane. Proper layout, grounding, and decoupling techniques must be used to achieve optimum performance (see Tutorial MT-031 and Tutorial MT-101).
Figure 1. 16 Channels of Programmable Output Voltage Span Using the AD5360 DAC (Simplified Schematic: Decoupling and All Connections Not Shown)
The circuit described here can be used with any of the AD536x devices mentioned above. The references can also be changed to give different output ranges if required.