datasheetbank_Logo   Integrated circuits, Transistor, Semiconductors Search and Datasheet PDF Download Site
Part Name :   

ADDAC80D-CBI-V View Datasheet(PDF) - Analog Devices

Part NameDescriptionManufacturer
ADDAC80D-CBI-V Complete Low Cost 12-Bit D/A Converters ADI
Analog Devices ADI
ADDAC80D-CBI-V Datasheet PDF : 16 Pages
First Prev 11 12 13 14 15 16
ADDAC80/ADDAC85/ADDAC87
VOLTAGE OUTPUT MODELS
Internal scaling resistors provided in the ADDAC80 may be
connected to produce bipolar output voltage ranges of ± 10 V,
± 5 V or ± 2.5 V or unipolar output voltage ranges of 0 V to +5 V
or 0 V to +10 V (see Figure 9).
TO REF
CONTROL
CIRCUIT
FROM
WEIGHTED
RESISTOR
NETWORK
REF
INPUT
16
6.3k
SUMMING
JUNCTION
20
18
5k
5k
+
17
BIPOLAR
OFFSET
21 COM
19
OUTPUT
15
Figure 9. Output Amplifier Voltage Range Scaling Circuit
Gain and offset drift are minimized in the ADDAC80 because
of the thermal tracking of the scaling resistors with other device
components. Connections for various output voltage ranges are
shown in Table III. Settling time is specified for a full-scale
range change: 4 s for a 10 kfeedback resistor; 3 s for a 5 k
feedback resistor when using the compensation capacitor shown
in Figure 3a.
The equivalent resistive scaling network and output circuit of
the current model are shown in Figures 10 and 11. External RLS
resistors are required to produce exactly 0 V to –2 V or ± 1 V
output. TCR of these resistors should be ± 100 ppm/°C or less
to maintain the ADDAC80 output specifications. If exact output
ranges are not required, the external resistors are not needed.
REF IN 16
TO REF CONTROL CIRCUIT
6.3k
17
3k
18
5k
15
2k
19
20
Figure 10. Internal Scaling Resistors
BIPOLAR OFFSET
REFERENCE
INPUT
17 6.3k
16
TO REF
CONTROL
CIRCUIT
15
I
0 TO 2mA
V 6.3V
+
6.6k
21
24
IOUT
COMMON
REFERENCE OUT
Figure 11. ADDAC80 Current Model Equivalent Output Circuit
Internal resistors are provided to scale an external op amp or to
configure a resistive load to offer two output voltage ranges of ±1 V
or 0 V to –2 V. These resistors (RLI TCR = 20 ppm/°C) are an
integral part of the ADDAC80 and maintain gain and bipolar
offset drift specifications. If the internal resistors are not used, exter-
nal RL (or RF) resistors should have a TCR of ± 25 ppm/°C or
less to minimize drift. This will typically add ± 50 ppm/°C + the
TCR of RL (or RF) to the total drift.
Table III. Output Voltage Range Connections, Voltage Model ADDAC80
Output
Range
Digital
Input Codes
± 10 V
±5 V
± 2.5 V
0 V to 10 V
0 V to 5 V
0 V to 10 V
COB or CTC
COB or CTC
COB or CTC
CSB
CSB
CCD
NC = No Connect
Connect
Pin 15 to
19
18
18
18
18
19
Connect
Pin 17 to
20
20
20
21
21
NC
Connect
Pin 19 to
15
NC
20
NC
20
15
Connect
Pin 16 to
24
24
24
24
24
24
DRIVING A RESISTIVE LOAD UNIPOLAR
A load resistance, RL = RLI, + RLS, connected as shown in
Figure 12 will generate a voltage range, VOUT, determined by:
VOUT
=
–2
mA

6.6
6.6
k
k
×
+
RL
RL

(1)
where RL max = 1.54 kand VOUT max = –2.5 V
To achieve specified drift, connect the internal scaling resistor
(RLI) as shown in Table IV to an external metal film trim resistor
(RLS) to provide full scale output voltage range of 0 V to –2 V.
With RLS = 0 V, VOUT = –1.69 V.
0 TO
2mA
6.6k
RLI
968
CURRENT CONTROLLED
BY DIGITAL INPUT
15
+
18 RLS
VOUT
21 COMMON
Figure 12. Equivalent Circuit ADDAC80-CBI-I Connected
for Unipolar Voltage Output with Resistive Load
REV. B
–11–
Direct download click here
 

Share Link : ADI
All Rights Reserved © datasheetbank.com 2014 - 2019 [ Privacy Policy ] [ Request Datasheet ] [ Contact Us ]