LM4050-4.1

or

LM4050-5.0

DAC121S101

DIN

SCLK

SYNC

0.47 PF

Input

Voltage

R

LM4130-4.1

DAC121S101

DIN

SCLK

SYNC

C1

0.1 PF

C2

2.2 PF

Input

Voltage

MICROWIRE

DEVICE

DAC121S101

CS

SK

SO

SCLK

DIN

SYNC

DAC121S101QML

SNAS410E – MAY 2008 – REVISED MARCH 2013

www.ti.com

Microwire Interface

Figure 38 shows an interface between a Microwire compatible device and the DAC121S101. Data is clocked out

on the rising edges of the SCLK signal.

Figure 38. Microwire Interface

USING REFERENCES AS POWER SUPPLIES

Recall the need for a quiet supply source for devices that use their power supply voltage as a reference voltage.

Since the DAC121S101 consumes very little power, a reference source may be used as 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 for the power supply of the DAC121S101. Listed below are a few power supply

options for the DAC121S101.

LM4130

The LM4130 reference, with its 0.05% accuracy over temperature, is a good choice as a power source for the

DAC121S101. Its primary disadvantage is the lack of 3 V and 5 V versions. However, the 4.096 V version is

useful if a 0 to 4.095 V output range is desirable or acceptable. Bypassing the LM4130 VIN pin with a 0.1 µF

capacitor and the VOUT pin with a 2.2 µF capacitor will improve stability and reduce output noise. The LM4130

comes in a space-saving 5-pin SOT23.

Figure 39. The LM4130 as a power supply

LM4050

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

DAC121S101. It does not come in a 3 Volt version, but 4.096 V and 5 V versions are available. It comes in a

space-saving 3-pin SOT23.

Figure 40. The LM4050 as a power supply

18

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