Datasheet
( )
REF _ MAX REF _ MIN
6
REF RANGE
V V
Drift Error 10 ppm / C
V T
-
æ ö
= ´ °
ç ÷
ç ÷
´
è ø
V A
OUT
V B
OUT
GND
LDAC
CLR
1
2
3
4
5
6
7
8
9
10
SYNC
SYNC
SCLK
SCLK
D
IN
D
IN
AV
DD
AV
DD
V /V
REFIN REFOUT
V /
V
REFIN
REFOUT
1
2
3
4
5
6
7
8
9
10
V A
OUT
V B
OUT
GND
LDAC
CLR
AV
DD
AV
DD
1 Fm
1 Fm
150 nF
150 nF
DGS
DSC
DAC8562, DAC8563
DAC8162, DAC8163
DAC7562, DAC7563
SLAS719D –AUGUST 2010–REVISED AUGUST 2012
www.ti.com
APPLICATION INFORMATION
INTERNAL REFERENCE
The internal reference of the DAC756x, DAC816x, and DAC856x does not require an external load capacitor for
stability because it is stable without any capacitive load. However, for improved noise performance, an external
load capacitor of 150 nF or larger connected to the V
REFIN
/V
REFOUT
output is recommended. Figure 94 shows the
typical connections required for operation of the DAC756x, DAC816x, and DAC856x internal reference. A supply
bypass capacitor at the AV
DD
input is also recommended.
Figure 94. Typical Connections for Operating the DAC756x/DAC816x/DAC856x Internal Reference
Supply Voltage
The internal reference features an extremely low dropout voltage. It can be operated with a supply of only 5 mV
above the reference output voltage in an unloaded condition. For loaded conditions, refer to the Load Regulation
section. The stability of the internal reference with variations in supply voltage (line regulation, DC PSRR) is also
exceptional. Within the specified supply voltage range of 2.7 V to 5.5 V, the variation at V
REFIN
/V
REFOUT
is
typically 50 µV/V; see Figure 7.
Temperature Drift
The internal reference is designed to exhibit minimal drift error, defined as the change in reference output voltage
over varying temperature. The drift is calculated using the box method described by Equation 3:
(3)
where:
V
REF_MAX
= maximum reference voltage observed within temperature range T
RANGE
.
V
REF_MIN
= minimum reference voltage observed within temperature range T
RANGE
.
V
REF
= 2.5 V, target value for reference output voltage.
T
RANGE
= the characterized range from –40°C to 125°C (165°C range)
The internal reference features an exceptional typical drift coefficient of 4 ppm/°C from –40°C to 125°C.
Characterizing a large number of units, a maximum drift coefficient of 10 ppm/°C is observed. Temperature drift
results are summarized in Figure 3.
Noise Performance
Typical 0.1-Hz to 10-Hz voltage noise and noise spectral density performance are listed in the Electrical
Characteristics. Additional filtering can be used to improve output noise levels, although care should be taken to
ensure the output impedance does not degrade the AC performance. The output noise spectrum at the
V
REFIN
/V
REFOUT
pin, both unloaded and with an external 4.7-µF load capacitor, is shown in Figure 6. Internal
reference noise impacts the DAC output noise when the internal reference is used.
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