pc87591l National Semiconductor Corporation, pc87591l Datasheet - Page 195

• Manufacturer Part Number: pc87591l
• Description: Lpc Mobile Embedded Controllers
• Manufacturer: National Semiconductor Corporation

Revision 1.07
Embedded Controller Modules
Output Settling Time
The DAC output settling time depends on the external load characteristics and the required accuracy. Figure 68 shows the
equivalent circuit used for evaluating DAC behavior. Each DAC output has a typical output impedance of 3 K
if the total load is a 50 pF capacitor only, the output settles to 1/2 LSB within 1 s. The total load capacitance is comprises
the analog output capacitance (C
Filtering Noise on Output Signals
Output signals may have unwanted noise caused by nearby digital circuits. When using slow changing signals in a noisy
environment, a low-pass filter (LPF) may be added externally. This may also be required in applications where the DAC out-
puts control sensitive circuits like audio amplifiers. This can be implemented as a simple RC circuit. The cutoff frequency of
this LPF should be above the required signal frequency.
AO
) and the external load capacitance (C
V
OUT
Equivalent Circuit
Figure 68. DAC Output Equivalent Circuit
DAC Output
(Continued)
RO
C
AO
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Load Circuit
Application
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C
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R
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