![Analog Devices ADuCM310 Скачать руководство пользователя страница 34](http://html1.mh-extra.com/html/analog-devices/aducm310/aducm310_hardware-reference-manual_2939956034.webp)
UG-549
ADuCM310 Hardware Reference Manual
Rev. C | Page 34 of 192
IDACs
IDAC FEATURES
The
provides six IDACs: five high current DAC sources and one current source and current sink (IDAC3) channel. The
current sources are low noise, low drift current outputs.
•
IDAC0: 0 mA to 100 mA full-scale output.
•
IDAC1: 0 mA to 100 mA full-scale output.
•
IDAC2: 0 mA to 200 mA full scale output.
•
IDAC3: 0 mA to 250 mA full-scale current source output (using IDAC3CON and IDAC3DAT). It can also be set as a current sink
capable of sinking up to 80 mA (using IDAC6CON and IDAC6DAT).
•
IDAC4: 0 mA to 20 mA full-scale output.
•
IDAC5: 0 mA to 20 mA full-scale output.
IDAC BLOCK DIAGRAM
BUF
BUF
3.16kΩ
R
EXT
5ppm
0.1%
PGND
PGND
PGND
PGND
AGND
PV
DD
IDAC3
3.3V
PV
DD
CDAMP
10nF
CC FOR DITHER
0.1nF
PULL-DOWN
100µA
SINK
CURRENT
ADC
INPUT
MUX
LDO
1.2V
V
REF
5-BIT
IDAC
11-BIT
IDAC
2.5V OUT
1
1461-
009
Figure 9. Example IDAC Circuit—IDAC3
IDAC OVERVIEW
Precision Current Generation and Fault Protection
The reference current for the IDACs is generated by a precision internal band gap voltage reference (V
BANDGAP
) and an external precision
resistor (R
REF
, 5 ppm, 0.1%). The reference current is equal to V
BANDGAP
divided by R
REF
. The band gap voltage reference is a low drift, high
accuracy voltage source that helps to minimize the overall IDAC gain error and gain error drift. The noise of the IDAC outputs is limited
by the low pass filter on the output stage; each IDAC requires a 10 nF capacitor between PV
DD
supply voltage and the CDAMP pin.
Figure 9 shows the typical architecture of the IDAC. The parallel 11-bit and 5-bit IDACs set the output current scale. The output of these
IDACs are summed together and fed to a current mirror and then are gained up at the output stage.
Production trimming of the LDO band gap reference aids performance. In addition, gain trimming and scaling of the current mirror and
output stages are also included in the ATE test program.