Datasheet

ADC1175

SNAS012H –JANUARY 2000–REVISED APRIL 2013

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Driving the reference to force desired values requires driving with a low impedance source, provided by the

transistors. Pins 16 and 22 are not connected.

Figure 21.

POWER SUPPLY CONSIDERATIONS

Many A/D converters draw sufficient transient current to corrupt their own power supplies if not adequately

bypassed. A 10µF tantalum or aluminum electrolytic capacitor should be placed within an inch (2.5 centimeters)

of the A/D power pins, with a 0.1 µF ceramic chip capacitor placed as close as possible to the converter's power

supply pins. Leadless chip capacitors are preferred because they have low lead inductance.

While a single voltage source should be used for the analog and digital supplies of the ADC1175, these supply

pins should be well isolated from each other to prevent any digital noise from being coupled to the analog power

pins. A wideband choke, such as the JW Miller FB20010-3B, is recommended between the analog and digital

supply lines, with a ceramic capacitor close to the analog supply pin. Avoid inductive components in the analog

supply line.

The converter digital supply should not be the supply that is used for other digital circuitry on the board. It should

be the same supply used for the A/D analog supply.

As is the case with all high speed converters, the ADC1175 should be assumed to have little a.c. power supply

rejection, especially when self-biasing is used by connecting V

and V

RTS

together.

Product Folder Links: ADC1175