LM4050-4.1

or

LM4050-5.0

0.47 PF

Input

Voltage

R

DAC124S085

DIN

SCLK

SYNC

0.1 PF

LM4132-4.1

DAC124S085

DIN

SCLK

SYNC

C1

0.1 PF

C2

2.2 PF

Input

Voltage

C3

0.1 PF

21

DAC124S085

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SNAS348G – MAY 2006 – REVISED APRIL 2016

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10 Power Supply Recommendations

10.1 Using References as Power Supplies

While the simplicity of the DAC124S085 implies ease of use, it is important to recognize that the path from the

DAC124S085 consumes very little power, a reference source may be used as the reference input or the supply

voltage. The advantages of using a reference source over a voltage regulator are accuracy and stability. Some

low noise regulators can also be used. Listed below are a few reference and power supply options for the

DAC124S085.

10.1.1 LM4132

The LM4132, with its 0.05% accuracy over temperature, is a good choice as a reference source for the

DAC124S085. The 4.096-V version is useful if a 0-V to 4.095-V output range is desirable or acceptable.

Bypassing the LM4132 VIN pin with a 0.1-µF capacitor and the VOUT pin with a 2.2-µF capacitor improves

stability and reduce output noise. The LM4132 comes in a space-saving 5-pin SOT23.

Figure 37. LM4132 Power Supply

10.1.2 LM4050

Available with accuracy of 0.44%, the LM4050 shunt reference is also a good choice as a reference for the

DAC124S085. It is available in 4.096-V and 5-V versions and comes in a space-saving 3-pin SOT23.

Figure 38. LM4050 Power Supply

The minimum resistor value in the circuit of Figure 38 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 DAC124S085 drawing zero current. The maximum

resistor value must allow the LM4050 to draw more than its minimum current for regulation plus the maximum

DAC124S085 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

DAC124S085 draws its maximum current. These conditions can be summarized with Equation 4 and Equation 5.