AN1740 Freescale Semiconductor / Motorola, AN1740 Datasheet - Page 19
![no-image](/images/no-image-200.jpg)
AN1740
Manufacturer Part Number
AN1740
Description
Applications Using the Analog Subsystem on MC68HC05JJ/JP Series Microcontrollers
Manufacturer
Freescale Semiconductor / Motorola
Datasheet
1.AN1740.pdf
(80 pages)
- Current page: 19 of 80
- Download datasheet (535Kb)
Comparator Input
Impedance
AN1740
MOTOROLA
NOTE:
flags, CPF1 and CPF2 in the ASR, may get set during any change in the
INV bit.
The user should use caution also when changing the state of the INV bit
if either flag bit is enabled to trigger a timer input capture or analog
interrupt. Any change to the INV bit should be done with these interrupts
disabled or during a time when an interrupt is not expected before the
flag bits can be cleared.
Changes to the INV, CP1EN, CP2EN, and ICEN bits can cause the
comparator static flags to get set. Always clear the CPF1 and CPF2
static flag bits after changing any configuration of the comparators by
writing a logical 1 to both the CPFR1 and CPFR2 bits in the ASR.
The comparators themselves have a very high input impedance, but
several other circuits connected to their inputs will lower this ideal
impedance. These currents or equivalent impedances are:
The ESD protection (1) and the parasitic capacitances (2) are always
present and will be the limiting factor on high input impedance. The
divider (3) only affects the negative input of comparator 2 and can be
removed from the input by not using the DHOLD bit in the AMUX
register. The last three sources (4, 5, 6) all can be controlled by the
1. Input protection diodes for ESD which may have leakage currents
2. Parasitic capacitances in the input and multiplexer circuitry will
3. The input divider of 2:1 has an impedance of 120 k at DC, but
4. Software-controlled input pulldown devices which can sink up to
5. More than one input multiplexer being on at the same time and
6. Output devices on port B pins being active
Freescale Semiconductor, Inc.
For More Information On This Product,
up to 2 A (equivalent of 2.5 M at 5 volts)
cause the input impedance to decrease with frequency as shown
in
decreases at high frequencies due to the sample capacitor as
shown in
280 A (equivalent of 18 k at 5 volts)
connecting the comparator input to other low impedances
Figure
Go to: www.freescale.com
Figure
9.
9.
Voltage Comparators
Application Note
19
Related parts for AN1740
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
![AN177](/images/no-image3.png)
Part Number:
Description:
An Overview og the Phase Locked Loop
Manufacturer:
Philips
Datasheet:
![AN1268](/images/manufacturer_photos/0/6/637/stmicroelectronics_tmb.jpg)
Part Number:
Description:
AN OVERVIEW OF THE LPC FLASH INTERFACE
Manufacturer:
STMicroelectronics
![AN1315](/images/no-image3.png)
Part Number:
Description:
An Evaluation System Interfacing the MPX2000 Series Pressure Sensors to a Microprocessor
Manufacturer:
Motorola / Freescale Semiconductor
![AN1998](/images/no-image3.png)
Part Number:
Description:
An FM-IF system for DECT and other high speed GFSK applications
Manufacturer:
Philips Semiconductors / NXP Semiconductors
![AN2124](/images/no-image3.png)
Part Number:
Description:
An 8 x 8 Discrete Cosine Transform on the StarCore SC140/SC1400 Cores
Manufacturer:
Freescale Semiconductor / Motorola
![AN2428](/images/no-image3.png)
Part Number:
Description:
An Overview of the HCS12 ATD Module
Manufacturer:
Freescale Semiconductor / Motorola
![AN2708](/images/no-image3.png)
Part Number:
Description:
An Introduction to the External Bus Interface on the HCS12X
Manufacturer:
Freescale Semiconductor / Motorola
![AN2783](/images/no-image3.png)
Part Number:
Description:
An RF Data Link Using Tango3 and Romeo2 RF Modules
Manufacturer:
Freescale Semiconductor / Motorola
![MC33394DH](/images/manufacturer_photos/0/2/262/freescale_semiconductor_tmb.jpg)
Part Number:
Description:
IC POWER SUPPLY MULT-OUT 44-HSOP
Manufacturer:
Freescale Semiconductor
Datasheet:
![MC33394DWB](/images/manufacturer_photos/0/2/262/freescale_semiconductor_tmb.jpg)
Part Number:
Description:
IC POWER SUPPLY MULT-OUT 54-SOIC
Manufacturer:
Freescale Semiconductor
Datasheet:
![MSC7110](/images/no-image3.png)
Part Number:
Description:
Low-Cost 16-Bit DSP with DDR Controller
Manufacturer:
Freescale Semiconductor / Motorola
![MSC7116](/images/no-image3.png)
Part Number:
Description:
Low-Cost 16-bit DSP with DDR Controller and 10/100 Mbps Ethernet MAC
Manufacturer:
Freescale Semiconductor / Motorola
Datasheet:
![MSC7119](/images/no-image3.png)
Part Number:
Description:
Low-Cost 16-bit DSP with DDR Controller and 10/100 Mbps Ethernet MAC
Manufacturer:
Freescale Semiconductor / Motorola
Datasheet:
![MSC7118](/images/no-image3.png)
Part Number:
Description:
Low-Cost 16-bit DSP with DDR Controller
Manufacturer:
Freescale Semiconductor / Motorola
Datasheet:
![MSC8101](/images/no-image3.png)
Part Number:
Description:
Functional Pin Difference Between the MSC8101 and MPC8260 Communications Processor Modules
Manufacturer:
Freescale Semiconductor / Motorola