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4.5
Internal Reference Operation
IOUT
FS
+
16
ǒ
V
EXTIO
R1
Ǔ
4.6
External Reference Operation
Circuit Description
The full-scale output current is set by applying an external resistor (R1) between the BIASJ pin of the
DAC5686 device and ground. The full-scale output current can be adjusted from 20 mA down to 2 mA by
varying R1 or changing the externally applied reference voltage. The full-scale output current, IOUTFS, is
defined as follows:
where VEXTIO is the voltage at pin EXTIO. This voltage is 1.2 V typical when using the internally provided
bandgap reference voltage source.
The internal reference can be disabled and overridden by an external reference by connecting a voltage
source to terminal TP1 (EXTI/O) and connecting EXTLO to +3.3VA with jumper W1 installed between pins
1 and 2. The specified range for external reference voltages must be observed (see the DAC5686 data
sheet (
) for details).
DAC5686 EVM
24
SLWU006E – December 2004 – Revised March 2007
