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V

OUT

D

65536

(1)

RRR

2R

2R

2R

R

5 kW

S2

S1

DGND

Digital Interface Connections Omitted For Clarity.

DAC8814

SBAS338 – JANUARY 2005

used by the logic to drive the DAC switches on and off. Note that a matching switch is used in series with the

internal 5 k

Ω feedback resistor. If users are attempting to measure the value of R

temperature applications to minimize zero-scale leakage currents that double every 10

°C. The DAC output

Figure 54. Typical Equivalent DAC Channel

The DAC is also designed to accommodate ac reference input signals. The DAC8814 accommodates input

reference voltages in the range of -12 V to +12 V. The reference voltage inputs exhibit a constant nominal input

resistance of 5 k

Ω, ± 30%. On the other hand, the DAC outputs I

various output resistances and capacitances.

The choice of external amplifier should take into account the variation in impedance generated by the DAC8814

on the amplifiers' inverting input node. The feedback resistance, in parallel with the DAC ladder resistance,

dominates output voltage noise. For multiplying mode applications, an external feedback compensation capacitor

voltages.

Figure 26 shows the gain vs frequency performance at various attenuation settings using a 23 pF external

performance, power supply bypassing of 0.01 µF, in parallel with 1 µF, is recommended. Under these conditions,

clean power supply with low ripple voltage capability should be used. Switching power supplies is usually not

best to derive the DAC8814 5-V supply from the system analog supply voltages. (Do not use the digital 5-V

supply.) See Figure 55.

23