DAC101S101QCMKX/NOPB National Semiconductor, DAC101S101QCMKX/NOPB Datasheet - Page 16

• Manufacturer Part Number: DAC101S101QCMKX/NOPB
• Description: DAC RRO 10BIT MICROPWR TSOT23-6
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of DAC101S101QCMKX/NOPB

• Settling Time: 8µs
• Number Of Bits: 10
• Data Interface: Serial
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Power Dissipation (max): 1.41mW
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-6, TSOT-6
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: DAC101S101QCMKX

www.national.com
2.2.2 LM4050
Available with accuracy of 0.44%, the LM4050 shunt refer-
ence is also a good choice as a power regulator for the
DAC101S101. It does not come in a 3 Volt version, but 4.096V
and 5V versions are available. It comes in a space-saving 3-
pin SOT23.
The minimum resistor value in the circuit of
be chosen such that the maximum current through the
LM4050 does not exceed its 15 mA rating. The conditions for
maximum current include the input voltage at its maximum,
the LM4050 voltage at its minimum, the resistor value at its
minimum due to tolerance, and the DAC101S101 draws zero
current. The maximum resistor value must allow the LM4050
to draw more than its minimum current for regulation plus the
maximum DAC101S101 current in full operation. The condi-
tions for minimum current include the input voltage at its
minimum, the LM4050 voltage at its maximum, the resistor
value at its maximum due to tolerance, and the DAC101S101
draws its maximum current. These conditions can be sum-
marized as
and
where V
voltages ± the LM4050 output tolerance over temperature, I
(max) is the maximum allowable current through the LM4050,
I
proper regulation, I
ply current, and I
current.
2.2.3 LP3985
The LP3985 is a low noise, ultra low dropout voltage regulator
with a 3% accuracy over temperature. It is a good choice for
applications that do not require a precision reference for the
DAC101S101. It comes in 3.0V, 3.3V and 5V versions, among
Z
(min) is the minimum current required by the LM4050 for
R(max) = ( V
R(min) = ( V
FIGURE 10. The LM4050 as a power supply
Z
(min) and V
A
IN
IN
(min) is the minimum DAC101S101 supply
A
(max) − V
(min) − V
(max) is the maximum DAC101S101 sup-
Z
(max) are the nominal LM4050 output
Z
Z
(max) / (I
(min) / (I
A
A
(min) + I
(max) + I
Figure 10
Z
Z
(max))
(min) )
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should
Z
16
others, and sports a low 30 µV noise specification at low fre-
quencies. Since low frequency noise is relatively difficult to
filter, this specification could be important for some applica-
tions. The LP3985 comes in a space-saving 5-pin SOT23 and
5-bump micro SMD packages.
An input capacitance of 1.0µF without any ESR requirement
is required at the LP3985 input, while a 1.0µF ceramic ca-
pacitor with an ESR requirement of 5mΩ to 500mΩ is required
at the output. Careful interpretation and understanding of the
capacitor specification is required to ensure correct device
operation.
2.2.4 LP2980
The LP2980 is an ultra low dropout regulator with a 0.5% or
1.0% accuracy over temperature, depending upon grade. It is
available in 3.0V, 3.3V and 5V versions, among others.
Like any low dropout regulator, the LP2980 requires an output
capacitor for loop stability. This output capacitor must be at
least 1.0µF over temperature, but values of 2.2µF or more will
provide even better performance. The ESR of this capacitor
should be within the range specified in the LP2980 data sheet.
Surface-mount solid tantalum capacitors offer a good combi-
nation of small size and ESR. Ceramic capacitors are attrac-
tive due to their small size but generally have ESR values that
are too low for use with the LP2980. Aluminum electrolytic
capacitors are typically not a good choice due to their large
size and have ESR values that may be too high at low tem-
peratures.
FIGURE 11. Using the LP3985 regulator
FIGURE 12. Using the LP2980 regulator
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