SLAS352C − DECEMBER 2001 − REVISED AUGUST 2004
detailed description (continued)
The DAC5675 comprises a bandgap reference and control amplifier for biasing the full-scale output current. The
full-scale output current is set by applying an external resistor RBIAS. The bias current IBIAS through resistor
RBIAS is defined by the on-chip bandgap reference voltage and control amplifier. The full-scale output current
equals 16 times this bias current. The full-scale output current IO(FS) is thus expressed as:
IO(FS) + 16
where VEXTIO is the voltage at terminal EXTIO. The bandgap reference voltage delivers an accurate voltage
of 1.2 V. This reference can be override by applying a external voltage to terminal EXTIO. The bandgap
reference can additionally be used for external reference operation. In that case, an external buffer with high
impedance input should be applied in order to limit the bandgap load current to a maximum of 100 nA. The
capacitor CEXT may be omitted. Terminal EXTIO serves as either a input or output node. The full-scale output
current is adjustable from 20 mA down to 2 mA by varying resistor RBIAS.
analog current outputs
Figure 10 shows a simplified schematic of the current source array output with corresponding switches.
Differential non switches direct the current of each individual PMOS current source to either the positive output
node IOUT1 or its complementary negative output node IOUT2. The output impedance is determined by the
stack of the current sources and differential switches, and is >300 kΩ in parallel with an output capacitance of
The external output resistors are referred to the positive supply AVDD.
Current Source Array
Figure 10. Equivalent Analog Current Output