DAC8562SDSCT Datasheet, PDF (38/58 Pages) Texas Instruments – DUAL 16-/14-/12-BIT, ULTRALOW-GLITCH, LOW-POWER, BUFFERED, VOLTAGE-OUTPUT DAC WITH 2.5-V, 4-PPM/°C INTERNAL REFERENCE IN SMALL 3-MM × 3-MM SON

DAC8562, DAC8563
DAC8162, DAC8163
DAC7562, DAC7563
SLAS719D – AUGUST 2010 – REVISED AUGUST 2012
APPLICATION INFORMATION
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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.
DGS
DSC
1 V_OUTA
2 V_OUTB
3 GND
V_REFIN/V_REFOUT 10
AV_DD 9
D_IN 8
150 nF
AV_DD
1 mF
1 V_OUTA
2 V_OUTB
3 GND
V_REFIN/ ₁₀
V_REFOUT
AV_DD 9
D_IN 8
150 nF
AV_DD
1 mF
4 LDAC
SCLK 7
4 LDAC
SCLK 7
5 CLR
SYNC 6
5 CLR
SYNC 6
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:
( ) Drift
Error
=
æ
ççè
V_{REF _ MAX} - V_{REF _ MIN}
V_REF ´ T_RANGE
ö
÷÷ø
´
10⁶
ppm / °C
(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.
38
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