AD7804/AD7805/AD7808/AD7809
AD7805/AD7809 PIN FUNCTION DESCRIPTIONS
AD7805
Pin No.
AD7809
Pin No.
1, 11, 13,
20, 33
2, 5, 39, 40
41, 42
43
3, 4, 6, 7, 9,
10, 15, 23
24, 26
8, 12
14
Mnemonic
NC
AGND
V
OUT
B, V
OUT
A
REFOUT
DB9–DB2
DB1, DB0
V
OUT
F, V
OUT
E
LDAC
Description
No Connect. These pins should be left open circuit.
Ground reference point for analog circuitry.
Analog output voltages from the DACs.
Reference Output. This is a bandgap reference and is typically 1.23 V.
Data Inputs. DB9 to DB2 are the 8 MSBs of the data word.
DB1 and DB0 function as the 2 LSBs of the 10-bit word in 10-bit parallel mode but
have other functions when BYTE loading structure is used.
Analog output voltages from the DACs.
LDAC
Input. When this digital input is taken low, all DAC registers are simultaneously
updated with the contents of the DAC data registers. If
LDAC
is permanently tied low, or is
low during the rising edge of
WR
similar to data inputs, an automatic update will take place.
Ground reference point for digital circuitry.
Digital Power Supply.
Write Input
WR
is an active low logic input which is used in conjunction with
CS
and
the address pins to write data to the relevant registers.
Chip Select. Active low logic input.
Asynchronous
CLR
Input. When this input is taken low, all Main DAC outputs are
cleared either to V
BIAS
or to V
BIAS
/16 volts. All Sub DACs are also cleared and thus the
transfer function of the MAIN DAC will remain centered around the V
BIAS
point.
Analog output voltages from the DACs.
DAC Address Inputs. These digital inputs are used in conjunction with
CS
and
WR
to
determine which DAC channel control register or DAC data register is loaded from the
input register. These address bits are don’t cares when writing to the system control register.
Logic Input. Logic high enables writing to the DAC data registers, a logic low enables
writing to the control registers.
This is an external reference input for the DAC. When this reference is selected for the DAC
in the control register, the analog output from the selected DAC swings around this point.
Compensation Pin. This pin provides an output from the internal V
DD
/2 divider and is
provided for ac bypass purposes only. This pin should be decoupled with 1 nF capacitors
to both AV
DD
and AGND. This pin can be overdriven with an external reference, thus
giving the facility for two external references on the part.
Analog output voltages from the DACs.
Analog Power Supply.
Active low input used to put the part into low power mode reducing current consump-
tion to 1
µA.
AD7809 PIN CONFIGURATION
PD
REFOUT
V
OUT
A
V
OUT
B
AGND
AV
DD
V
OUT
C
V
OUT
D
AGND
AV
DD
COMP
33
NC
PIN 1
IDENTIFIER
32
REFIN
31
MODE
30
A0
29
A1
28
AV
DD
27
A2
26
DB0
25
V
OUT
G
24
DB1
23
DB2
12 13 14 15 16 17 18 19 20 21 22
1
2, 3
4
5–10,
12, 13
19, 20
11
14
15
16
17
18
16
17
18
21
19
DGND
DV
DD
WR
CS
CLR
21, 22
22, 25
27, 29, 30
V
OUT
H, V
OUT
G
A2, A1, A0
23
24
25
31
32
34
MODE
REFIN
COMP
26, 27
28
35, 36
28, 37, 38
44
V
OUT
D, V
OUT
C
AV
DD
PD
AD7805 PIN CONFIGURATION
AGND
1
V
OUT
B
2
V
OUT
A
3
REFOUT
4
DB9
5
DB8
6
DB7
7
28
AV
DD
27
V
OUT
C
26
V
OUT
D
25
COMP
24
REFIN
44 43 42 41 40 39 38 37 36 35 34
NC
1
AGND
2
DB9
3
DB8
4
AGND
5
DB7
6
DB6
7
V
OUT
F
8
DB5
9
DB4
10
NC
11
AD7805
23
MODE
TOP VIEW
22
A0
DB6
8
(Not to Scale)
21
A1
DB5
9
DB4
10
20
DB0
19
DB1
18
CLR
17
CS
16
WR
15
DV
DD
AD7809
TOP VIEW
(Not to Scale)
LDAC
11
DB3
12
DB2
13
DGND
14
V
OUT
E
NC
LDAC
DB3
DGND
DV
DD
WR
CLR
NC
NC = NO CONNECT
–8–
CS
V
OUT
H
REV. A
AD [ ANALOG DEVICES ]
