DAC5675

SLAS352C − DECEMBER 2001 − REVISED AUGUST 2004

11

www.ti.com

detailed description (continued)

reference operation

The DAC5675 comprises a bandgap reference and control amplifier for biasing the full-scale output current. The

I

O(FS) +

16

I

BIAS +

16

V

EXTIO

R

BIAS

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

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 k

Ω in parallel with an output capacitance of

5 pF.

The external output resistors are referred to the positive supply AVDD.

Current Source Array

IOUT2

3.3 V

(AVDD)

RLOAD

S(1)

S(1)C

S(2)

S(2)C

S(N)

S(N)C

AGND

DAC5675

IOUT1

RLOAD

Figure 10. Equivalent Analog Current Output