MC68HC705CT4 Datasheet, PDF (20/152 Pages) Freescale Semiconductor, Inc – General Release Specification

Freescale Semiconductor, Inc.
General Description
1.4 Signal Description
The following paragraphs describe the signals.
1.4.1 V_DD and V_SS
Power is supplied to the microcontroller’s digital circuits using these two
pins. V_DD is the positive supply and V_SS is ground.
1.4.2 V_DD2 and V_SS2
Power is supplied to noise-susceptible circuitry such as the phase-
locked loop (PLL), comparators, and oscillators that require “cleaner”
supplies using these two pins. V_DD2 is the positive supply and V_SS2 is
ground.
1.4.3 Maskable Interrupt Request (IRQ/V_PP)
This pin supplies the EPROM with the required programming voltage. In
addition, this pin has a mask option as specified by the user that
provides one of two different choices of interrupt triggering sensitivity.
The options are:
1. Negative edge-sensitive triggering only
2. Both negative edge-sensitive and level-sensitive triggering
The microcontroller unit (MCU) completes the current instruction before
it responds to the interrupt request. When IRQ goes low for at least one
t_ILIH, a logic 1 is latched internally to signify that an interrupt has been
requested. When the MCU completes its current instruction, the interrupt
latch is tested. If the interrupt latch contains a logic 1 and the interrupt
mask bit (I bit) in the condition code register is clear, the MCU then
begins the interrupt sequence.
If the option is selected to include level-sensitive triggering, the IRQ input
requires an external resistor to V_DD for wire-OR operation.
General Release Specification
MC68HC705CT4 — Rev. 2.0
20
General Description
MOTOROLA
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