MAX5018A Ver la hoja de datos (PDF) - Maxim Integrated

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MAX5018A

8-Bit, High-Speed DAC

Maxim Integrated 

8-Bit, High-Speed DAC

Figure 1. Typical Interface Circuit

This device also has two analog ground pins (VCC). Tie

both ground pins to the analog ground plane. All power

and ground pins must be connected in any application.

If a +5V power source is required, the VCC ground pins

become the positive supply pins, while the VEE supply

pins become the ground pins. The relative polarities of

the other input and output voltages must be main-

tained.

Reference Considerations

The MAX5018 has two reference inputs (Ref+ and Ref-).

The input pins are connected to the inverting and non-

inverting inputs of an internal amplifier that serves as a

reference buffer amplifier.

The buffer amplifier’s output is the reference for the cur-

rent sinks. The amplifier feedback loop is connected

around one of the current sinks for better accuracy.

(See Figure 3.)

Since the analog output currents are proportional to the

digital input data and ISet, full-scale output can be

adjusted by varying the reference current. ISet is con-

trolled through the MAX5018’s Ref+ input. Figure 1

shows the method and the necessary equations for set-

ting ISet. The MAX5018 uses an external negative-

voltage reference. The external reference must be

stable to achieve a satisfactory output, and Ref- should

be driven through a resistor to minimize offsets caused

by bias current. To change the full-scale output, vary

the value for ISet with the 500Ω trimmer. A double 50Ω

load (25Ω) can be driven if ISet is increased by 50% for

doubly terminated 75Ω video applications.

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