AN1740 Freescale Semiconductor / Motorola, AN1740 Datasheet - Page 28

• Manufacturer Part Number: AN1740
• Description: Applications Using the Analog Subsystem on MC68HC05JJ/JP Series Microcontrollers
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
Analog Signal Multiplexers
28
NOTE:
Discharging large capacitors or low impedance loads into the PB0 pin
can cause high current spikes which may disrupt the internal analog V
with respect to the V
Repeated high currents can also damage the discharge device and/or
the device’s interconnect metal. Using capacitors that are less than 2 F
and discharge current peaks that are less than 25 mA is recommended.
The current source and discharge device is an important part of building
a single slope A/D convertor. In conjunction with A/D conversions, the
ATD1 and ATD2 mode bits in the ACR can provide some automatic
switching between the current source and sink modes of operation.
The analog signal multiplexer is shown in
the bits in the AMUX register at location $0003. By design, this register
has minimal interlocking between some of these control bits. The reason
for this is to allow combinations of channels to perform such tasks as
current summing and load switching.
The analog signal multiplexer is divided into two sections:
•
•
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The channel select bus
The comparator input bus
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pin and cause unwanted analog noise.
Figure
12. It is controlled by
MOTOROLA
AN1740
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