AD7709 Analog Devices, AD7709 Datasheet - Page 9

• Manufacturer Part Number: AD7709
• Description: 16-Bit Sigma Delta ADC with Current Sources, Switchable Reference Inputs and I/O Port
• Manufacturer: Analog Devices

Specifications of AD7709

• Resolution (bits): 16bit
• # Chan: 4
• Sample Rate: n/a
• Interface: Ser,SPI
• Analog Input Type: Diff-Uni,SE-Uni
• Ain Range: (2Vref/PGA Gain) p-p
• Adc Architecture: Sigma-Delta
• Pkg Type: SOP

Pin No. Mnemonic Function
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
REV. A
IOUT1
IOUT2
REFIN1(+) Positive Reference Input. REFIN1(+) can lie anywhere between V
REFIN1(–) Negative Reference Input. This reference input can lie anywhere between GND and V
AIN1
AIN2
AIN3/P3
AIN4/P4
AINCOM
REFIN2(+) Positive Reference Input. REFIN2(+) can lie anywhere between V
REFIN2(–) Negative Reference Input. This reference input can lie anywhere between GND and V
P2/SW2
PWRGND
P1/SW1
RESET
SCLK
CS
RDY
DOUT
DIN
GND
V
XTAL2
XTAL1
DD
Output for Internal Excitation Current Source. Either current source IEXC1, IEXC2, IEXC3, or a combina-
tion of the current sources, can be switched to this output.
Output for Internal Excitation Current Source. Either current source IEXC1, IEXC2, IEXC3, or a combina-
tion of the current sources, can be switched to this output.
ence voltage (REFIN1(+) – REFIN1(–)) is 2.5 V, but the part is functional with a reference range from 1 V to V
Analog Input. Programmable gain input that can be used as a pseudo-differential input when used with
AINCOM or as the positive input of a fully differential input pair when used with AIN2.
Analog Input. Programmable gain input that can be used as a pseudo-differential input when used with
AINCOM or as the negative input of a fully differential input pair when used with AIN1.
Analog Input/Digital Port Bit. Programmable gain input that can be used as a pseudo-differential input when
used with AINCOM or as the positive input of a fully differential input pair when used with AIN4. This pin
can also be programmed as a general-purpose digital input bit.
Analog Input/Digital Port Bit. Programmable gain input that can be used as a pseudo-differential input when
used with AINCOM or as the negative input of a fully-differential input pair when used with AIN3. This pin
can also be programmed as a general-purpose digital input bit.
All analog inputs are referenced to this input when configured in pseudo-differential input mode.
voltage (REFIN2(+) – REFIN2(–)) is 2.5 V, but the part is functional with a reference range from 1 V to V
Dual-Purpose Pin. It can act as a general-purpose output (P2) bit or as a low-side power switch (SW2) to
PWRGND.
Ground Point for the Low-Side Power Switches SW2 and SW1. PWRGND must be tied to GND.
Dual-Purpose Pin. It can act as a general-purpose output (P1) bit or as a low-side power switch (SW1) to
PWRGND.
Digital Input Used to Reset the ADC to Its Power-On-Reset Status. This pin has a weak pull-up internally to V
Serial Clock Input for Data Transfers to and from the ADC. The SCLK has a Schmitt-triggered input making
the interface suitable for opto-isolated applications. The serial clock can be continuous with all data transmitted
in a continuous train of pulses. Alternatively, it can be a noncontinuous clock with the information being
transmitted to or from the AD7709 in smaller batches of data. A weak pull-up to V
SCLK input.
Chip Select Input. This is an active low logic input used to select the AD7709. CS can be used to select the
AD7709 in systems with more than one device on the serial bus or as a frame synchronization signal in com-
municating with the device. CS can be hardwired low allowing the AD7709 to operate in 3-wire mode with
SCLK, DIN, and DOUT used to interface with the device. A weak pull-up to V
RDY is a Logic Low Status Output from the AD7709. RDY is low if the ADC has valid data in its data
register. This output returns high on completion of a read operation from the data register. If data is not
read, RDY will return high prior to the next update indicating to the user that a read operation should
not be initiated.
Serial Data Output Accessing the Output Shift Register of the AD7709. The output shift register can contain
data from any of the on-chip data or control registers.
Serial Data Input Accessing the Input Shift Register on the AD7709. Data in this shift register is transferred to
the control registers within the ADC, the selection bits of the communications register selecting which
control register. A weak pull-up to V
Ground Reference Point for the AD7709
Supply Voltage, 3 V or 5 V Nominal
Output from the 32.768 kHz Crystal Oscillator Inverter
Input to the 32.768 kHz Crystal Oscillator Inverter
PIN FUNCTION DESCRIPTIONS
DD
is provided on the DIN input.
–9–
DD
DD
and GND + 1 V. The nominal reference
and GND + 1 V. The nominal refer-
DD
is provided on the CS input.
DD
DD
DD
– 1 V.
– 1 V.
is provided on the
AD7709
DD
DD
DD
.
.
.