AD7864 Analog Devices, AD7864 Datasheet - Page 7

• Manufacturer Part Number: AD7864
• Description: High Speed, Low Power, 4-channel Simultaneous Sampling, 12-Bit ADC
• Manufacturer: Analog Devices

Specifications of AD7864

• Resolution (bits): 12bit
• # Chan: 4
• Sample Rate: 520kSPS
• Interface: Par
• Analog Input Type: SE-Bip,SE-Uni
• Ain Range: Bip 10V,Bip 2.5V,Bip 5.0V,Uni 2.5V,Uni 5.0V
• Adc Architecture: SAR
• Pkg Type: QFP

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Table 4. Pin Function Descriptions
Pin No.
1
2
3
4
5
6
7 to 10
11
12
13 to 16
17
18 to 21
22
23
24
25
26
Mnemonic
BUSY
FRSTDATA
CONVST
CS
RD
WR
SL1 to SL4
H /S SEL
AGND
V
AGND
V
STBY
V
V
AV
AGND
IN4x
IN2x
REF
REF
DD
GND
, V
, V
IN3x
IN1x
Analog Ground. General analog ground. Connect this AGND pin to the AGND plane of the system.
Analog Ground. Analog ground reference for the attenuator circuitry. Connect this AGND pin to the AGND plane
Reference Ground. This is the ground reference for the on-chip reference buffer of the part. Connect the
Analog Ground. Analog ground reference for the DAC circuitry.
Description
Busy Output. The busy output is triggered high by the rising edge of CONVST and remains high until conversion
is completed on all selected channels.
First Data Output. FRSTDATA is a logic output which, when high, indicates that the output data register pointer
is addressing Register 1—see the Accessing the Output Data Registers section.
Convert Start Input. Logic input. A low-to-high transition on this input puts all track-and-holds into their hold
mode and starts conversion on the selected channels. In addition, the state of the channel sequence selection is
also latched on the rising edge of CONVST .
Chip Select Input. Active low logic input. The device is selected when this input is active.
Read Input. Active low logic input that is used in conjunction with CS low to enable the data outputs. Ensure the
WR pin is at logic high while performing a read operation.
Write Input. A rising edge on the WR input, with CS low and RD high, latches the logic state on DB0 to DB3 into
the channel select register.
Hardware Channel Select. Conversion sequence selection can also be made via the SL1 to SL4 pins if H /S SEL is
Logic 0. The selection is latched on the rising edge of CONVST . See the
Hardware/Software Select Input. When this pin is at Logic 0, the AD7864 conversion sequence selection is
controlled via the SL1 to SL4 input pins. When this pin is at Logic 1, the sequence is controlled via the channel
select register. See the Selecting a Conversion Sequence section.
Analog Inputs. See the Analog Input section.
of the system.
Analog Inputs. See the Analog Input section.
Standby Mode Input. TTL-compatible input that is used to put the device into the power save or standby mode.
The STBY input is high for normal operation and low for standby operation.
V
Reference Input/Output. This pin provides access to the internal reference (2.5 V ± 5%) and also allows the
internal reference to be overdriven by an external reference source (2.5 V). Connect a 0.1 μF decoupling
capacitor between this pin and AGND.
Analog Positive Supply Voltage, 5.0 V ± 5%.
REF
GND pin to the AGND plane of the system.
FRSTDAT
CONVST
H/S SEL
BUSY
SL1
SL2
SL3
SL4
WR
RD
CS
A
10
11
1
2
3
4
5
6
7
8
9
44
12 13 14 15 16 17 18 19 20 21 22
43
PIN 1
Figure 3. Pin Configuration
42
Rev. D | Page 7 of 28
41
(Not to Scale)
AD7864
TOP VIEW
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
DB7
DB8
DB9
DB10
DB11
CLKIN
INT/EXT CLK
AGND
AV
V
V
REF
REF
DD
GND
Selecting a Conversion Sequence
AD7864
section.