Datasheet

AD7723
Rev. C | Page 11 of 32
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
12 13 14 15 16 17 18 19
20
21 22
3
4
5
6
7
1
2
10
11
8
9
40 39 3841
42
4344 36 35 3437
PIN 1
IDENTIFIER
TOP VIEW
(Not to Scale)
29
30
31
32
27
28
25
26
23
24
33
SCR/DB13
DGND/DB14
DOE/DB4
DGND/DB15
SFMT/DB5
DV
DD
/CS
FSI/DB6
SYNC
SCO/DB7
DGND
DV
DD
STBY
SDO/DB8
AV
DD
FSO/DB9
CLKIN
TSI/DB10
XTAL
SLP/DB11
XTAL_OFF
SLDR/DB12
HALF_PWR
AGND
AGND
DGND/DB2
DGND/DB1
DGND/DB0
CFMT/RD
DGND/DRDY
DGND
MODE2
MODE1
AGND1
AGND1
AV
DD1
AV
DD
AGND
UNI
REF2
VIN(–)
VIN(+)
REF1
AGND2
AD7723
DGND/DB3
01186-011
Figure 11. 44-Lead MQFP
Table 6. Pin Function Descriptions
Pin No. Mnemonic Description
6, 28 DGND Ground Reference for Digital Circuitry.
8, 7 MODE1/MODE2
Mode Control Inputs. The MODE1 and MODE2 pins choose either parallel or serial data interface operation
and select the operating mode for the digital filter in parallel mode. See Table 3 and Table 4.
9, 10 AGND1 Digital Logic Power Supply Ground for the Analog Modulator.
11 AV
DD1
Digital Logic Power Supply Voltage for the Analog Modulator.
12 CLKIN
Clock Input. An external clock source can be applied directly to this pin with XTAL_OFF tied high.
Alternatively, a parallel resonant fundamental frequency crystal, in parallel with a 1 MΩ resistor, can
be connected betweenthe XTAL pin and the CLKIN pin with XTAL_OFF tied low. External capacitors
are then required from the CLKIN and XTAL pins to ground. Consult the crystal manufacturer’s
recommendation for the load capacitors.
13 XTAL Input to Crystal Oscillator Amplifier. If an external clock is used, XTAL should be tied to AGND1.
14 XTAL_OFF
Oscillator Enable Input. A logic high disables the crystal oscillator amplifier to allow use of an external
clock source. Set low when using an external crystal between the CLKIN and XTAL pins.
15 HALF_PWR
When set high, the power dissipation is reduced by approximately one-half, and a maximum CLKIN
frequency of 10 MHz applies.
16, 18, 25 AGND Power Supply Ground for the Analog Modulator.
17, 26 AV
DD
Positive Power Supply Voltage for the Analog Modulator.
19 VIN(−) Negative Terminal of the Differential Analog Input.
20 VIN(+) Positive Terminal of the Differential Analog Input.
21 REF1
Reference Output. REF1 connects through 3 kΩ to the output of the internal 2.5 V reference and to a buffer
amplifier that drives the Σ-∆ modulator.
22 AGND2 Power Supply Ground Return to the Reference Circuitry, REF2, of the Analog Modulator.
23 REF2
Reference Input. REF2 connects to the output of an internal buffer amplifier that drives the Σ-∆ modulator.
When REF2 is used as an input, REF1 must be connected to AGND to disable the internal buffer amplifier.
24 UNI
Analog Input Range Select Input. The UNI pin selects the analog input range for either bipolar or unipolar
operation. A logic high input selects unipolar operation and a logic low selects bipolar operation.
27 STBY Standby Logic Input. A logic high sets the AD7723 into the power-down state.