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AD7242/AD7244
REV. A
–5–
AD7242/AD7244 PIN FUNCTION DESCRIPTION
DIP
Pin No.
Mnemonic
Description
1
LDACA
Load DAC, Logic Input. A new word is transferred into DAC Latch A from input Latch A on the fall-
ing edge of this signal. If
LDACA
is hard-wired low, data is transferred from input Latch A to DAC
Latch A on the sixteenth falling edge of TCLKA after
TFSA
goes low.
Transmit Frame Synchronization, Logic Input. This is a frame or synchronization signal for DACA
data with serial data expected after the falling edge of this signal.
Transmit Data, Logic Input. This is the data input which is used in conjunction with
TFSA
and
TCLKA to transfer serial data to input Latch A.
Transmit Clock, Logic Input. Serial data bits for DACA are latched on the falling edge of TCLKA
when
TFSA
is low.
Digital Ground. Both DGND pins for the device must be tied together at the device.
Test Pin 1. Used when testing the device. Do not connect anything to this pin.
Positive Power Supply, 5 V
±
5%. Both V
DD
pins for the device must be tied together at the device.
Analog Ground. Both AGND pins for the device must be tied together at the device.
Analog Output Voltage from DACB. This output comes from a buffer amplifier. The range is bipolar,
±
3 V with REF INB = +3 V.
Negative Power Supply, –5 V
±
5%. Both V
SS
pins for the device must be tied together at the device.
Test Pin 2. Used when testing the device. Do not connect anything to this pin.
DACB Voltage Reference Input. The voltage reference for DACB is applied to this pin. It is internally
buffered before being applied to DACB. The nominal reference voltage for correct operation of the
AD7242/AD7244 is 3 V.
Load DAC, Logic Input. A new word is transferred into DAC Latch B from input Latch B on the fall-
ing edge of this signal. If
LDACB
is hard-wired low, data is transferred from input Latch B to DAC
Latch B on the sixteenth falling edge of TCLKB after
TFSB
goes low.
Transmit Frame Synchronization, Logic Input. This is a frame or synchronization signal for DACB
data with serial data expected after the falling edge of this signal.
Transmit Data, Logic Input. This is the data input used in conjunction with
TFSB
and TCLKB to
transfer serial data to input Latch B.
Transmit Clock, Logic Input. Serial data bits for DACB are latched on the falling edge of TCLKB
when
TFSB
is low.
Digital Ground. Both DGND pins for the device must be tied together at the device.
Test Pin 3. Used when testing the device. Do not connect anything to this pin.
Positive Power Supply, 5 V
±
5%. Both V
DD
pins for the device must be tied together at the device.
Analog Ground. Both AGND pins for the device must be tied together at the device.
Analog Output Voltage from DACA. This output comes from a buffer amplifier. The range is bipolar,
±
3 V with REF INA = +3 V.
Negative Power Supply, –5 V
±
5%. Both V
SS
pins for the device must be tied together at the device.
Voltage Reference Output. To operate the DACs with this internal reference, REF OUT should be
connected to both REF INA and REF INB. The external load capability of the reference is 500
μ
A.
DACA Voltage Reference Input. The voltage reference for DACA is applied to this pin. It is internally
buffered before being applied to DACA. The nominal reference voltage for correct operation of the
AD7242/AD7244 is 3 V.
2
TFSA
3
DTA
4
TCLKA
5
6
7
8
9
DGND
TP1
V
DD
AGND
V
OUTB
10
11
12
V
SS
TP2
REF INB
13
LDACB
14
TFSB
15
DTB
16
TCLKB
17
18
19
20
21
DGND
TP3
V
DD
AGND
V
OUTA
22
23
V
SS
REF OUT
24
REF INA