User Manual

Operation Theory 25

4.2 Analog Output Status Register

The DAC uses a series bus architecture hence there is a delay in

the output of the digital value. The data transfer time for every DA

data write takes 13

µs, therefore the software driver must wait for

µs before sending another set of data to any analog output port.

While the DA value is sending, the Data_Send bit is ‘H’. The soft-

ware driver should check this bit before writing any data to the out-

put port. This register is read only.

4.3 Current Output and Range Control

A precision voltage-to-current converter XTR110 implements the

current output. The current output channel n (An) is control by the

voltage of channel n (Vn). A block diagram of the current output

channels is shown in the figure below:

Figure 4-1: Current Output Circuit

The PCI-6308A provides an on board +15V power supply. Each

current output channel is a current source, which is controlled by

the voltage of the corresponding voltage output channel. For

Base D16~D1 D0

0x00 X Data_Send

XTR110

50 Ohm

On Board +15V

External Load

(Resister R

= 250 Ohm typical)

A.GND

Current Output

Range Control