MC68HC05JJ6 Datasheet, PDF (134/216 Pages) Freescale Semiconductor, Inc – General Release Specification Microcontrollers

Analog Subsystem
to pull down any voltage source that may be connected to that pin.
Also, since voltage comparator 2 is always connected to two of the
port B I/O pins, these pins should be configured as inputs and have
their software programmable pulldowns disabled.
8.9 Current Source Features
The internal current source connected to the PB0/AN0 pin supplies
about 100 µA of current when the discharge device is disabled and the
current source is active. Therefore, this current source can be used in an
application if the ISEN enable bit is set to power up the current source
and by setting the A/D conversion method to manual mode 0 (ATD1 and
ATD2 cleared) and the charge current is enabled (CHG set).
8.10 Internal Temperature Sensing Diode Features
An internal diode is forward biased to V_SS and will have its voltage
change approximately 2 mV for each degree Centigrade rise in the
temperature of the device. This temperature-sensing diode is powered
up from a current source only during the time that the diode is selected.
When on, this current source adds about 30 µA to the I_DD current.
The temperature-sensing diode can be selected by setting both the
HOLD and DHOLD bits in the AMUX register (see 8.3 Analog Multiplex
Register).
8.11 Sample and Hold
When using the internal sample capacitor to capture a voltage for later
conversion, the HOLD or DHOLD bit must be cleared first before
changing any channel selection. If both the HOLD (or DHOLD) bit and
the channel selection are changed on the same write cycle, the sample
may be corrupted during the switching transitions.
General Release Specification
134
Analog Subsystem
MC68HC05JJ6/MC68HC05JP6 — Rev. 3.2
Freescale Semiconductor