AD7804/AD7805/AD7808/AD7809
AD7804/AD7808 PIN FUNCTION DESCRIPTION
AD7804
Pin No.
AD7808
Pin No. Mnemonic
Description
1
2, 3
4
1, 6
2, 3
4
AGND
OUTB, VOUT
REFOUT
Ground reference point for analog circuitry.
Analog output voltage from the DACs.
Reference Output. This is a bandgap reference and is typically 1.23 V.
V
A
5
PD
Active low input used to put the part into low power mode reducing current consumption
to 1 µA.
7, 8
9
V
FSIN
OUTF, VOUT
E
Analog output voltages from the DACs.
5
6
Level-triggered control input (active low). This is the frame synchronization signal for the
input data. When FSIN goes low, it enables the input shift register and data is transferred
on the falling edges of CLKIN.
LDAC Input. When this digital input is taken low, all DAC registers are simultaneously
updated with the contents of the data registers. If LDAC is tied permanently low, or is
low on the sixteenth falling clock edge with timing similar to that of SDIN, an automatic
update will take place.
10
LDAC
7
11
SDIN
Serial Data Input. These devices accept a 16-bit word. Data is clocked into the input shift
register on the falling edge of CLKIN.
8
9
10
12
13
14
DGND
DVDD
CLKIN
Ground reference point for digital circuitry.
Digital Power Supply.
Clock Input. Data is clocked into the input shift register on the falling edges of CLKIN.
Duty Cycle should be between 40% and 60%.
11
15
CLR
Asynchronous CLR Input. When this input is taken low, all Main DAC outputs are
cleared either to VBIAS or to VBIAS/16 volts. All Sub DACs are also cleared and thus the
transfer function of the Main DAC will remain centered around the VBIAS point.
16
17, 18
20
NC
No Connect. This pin should be left open circuit.
Analog output voltages from the DACs.
This is an external reference input for the DACs. When this reference is selected for a
DAC in the control register, the analog output from the selected DAC swings around this
point.
VOUTH, VOUTG
REFIN
12
13
21
COMP
Compensation Pin. This pin provides an output from the internal VDD/2 divider and is
provided for ac bypass purposes only. This pin should be decoupled with 1 nF capacitors
to both AVDD and AGND. This pin can be overdriven with an external reference, thus
giving the facility for two external references on the part.
14, 15
16
22, 23
19, 24
V
AVDD
OUTD, VOUT
C
Analog output voltage from the DACs.
Analog Power Supply. +3.3 V to +5 V.
AD7808 PIN CONFIGURATION
AD7804 PIN CONFIGURATION
1
2
24
23
22
21
20
19
18
17
AGND
AV
V
DD
1
2
3
4
5
6
7
8
16 AV
DD
AGND
C
V
B
A
OUT
OUT
V
B
A
15
14
13
12
11
10
9
V
C
OUT
OUT
3
V
V
D
OUT
OUT
V
V
D
OUT
OUT
4
COMP
REFIN
REFOUT
AD7804
TOP VIEW
(Not to Scale)
REFOUT
COMP
REFIN
5
PD
AD7808
TOP VIEW
(Not to Scale)
FSIN
LDAC
SDIN
6
AV
DD
AGND
CLR
V
F
E
7
V
G
OUT
OUT
CLKIN
8
V
V
H
OUT
OUT
DGND
DV
DD
9
16 NC
15
FSIN
10
11
12
LDAC
SDIN
CLR
14
13
CLKIN
DGND
DV
DD
NC = NO CONNECT
REV. A
–7–
ETC [ ETC ]
