Datasheet

LM4050-4.1
or
LM4050-5.0
V
OUT
= 0V to 5V
0.47 PF
Input
Voltage
R
V
Z
DAC101C081/5
0.1 PF
I
Z
I
DAC
SDA
SCL
V
REF
V
A
DAC101C081, DAC101C081Q, DAC101C085
www.ti.com SNVS801A –APRIL 2012–REVISED MARCH 2013
LM4050
Available with accuracy of 0.44%, the LM4050 shunt reference is also a good choice as a reference for the
DAC101C081. It is available in 4.096V and 5V versions and comes in a space-saving 3-pin SOT-23.
Figure 31. The LM4050 as a Power Supply
The minimum resistor value in the circuit of Figure 31 must 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, and the DAC101C081 drawing zero current. The maximum
resistor value must allow the LM4050 to draw more than its minimum current for regulation plus the maximum
DAC101C081 current in full operation. The conditions 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
DAC101C081 draws its maximum current. These conditions can be summarized as:
R(min) = ( V
IN
(max) − V
Z
(min) ) /I
Z
(max) (4)
and
R(max) = ( V
IN
(min) − V
Z
(max) ) / ( (I
DAC
(max) + I
Z
(min) )
where
• V
Z
(min) and V
Z
(max) are the nominal LM4050 output voltages ± the LM4050 output tolerance over
temperature
• I
Z
(max) is the maximum allowable current through the LM4050
• I
Z
(min) is the minimum current required by the LM4050 for proper regulation and
• I
DAC
(max) is the maximum DAC101C081 supply current. (5)
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