DS80C320 Datasheet, PDF (3/40 Pages) Dallas Semiconductor – High-Speed/Low-Power Micro

Figure 1. Block Diagram
DS80C320/DS80C323 High-Speed/Low-Power Microcontrollers
DS80C320/
DS80C323
PIN DESCRIPTION
PIN
DIP PLCC TQFP
NAME
40
44
38
20 22, 23 16, 17
V_CC
GND
9
10
4
RST
18 20
19 21
14 XTAL2
15 XTAL1
29 32
26
PSEN
FUNCTION
+5V (+3V for DS80C323)
Digital Circuit Ground
Reset Input. The RST input pin contains a Schmitt voltage input to
recognize external active-high reset inputs. The pin also employs an
internal pulldown resistor to allow for a combination of wired OR
external reset sources. An RC is not required for power-up, as the device
provides this function internally.
Crystal Oscillator Pins. XTAL1 and XTAL2 provide support for
parallel-resonant, AT-cut crystals. XTAL1 acts also as an input in the
event that an external clock source is used in place of a crystal. XTAL2
serves as the output of the crystal amplifier.
Program Store-Enable Output, Active Low. This signal is commonly
connected to external ROM memory as a chip enable. PSEN provides an
active-low pulse width of 2.25 XTAL1 cycles with a period of four
XTAL1 cycles. PSEN is driven high when data memory (RAM) is being
accessed through the bus and during a reset condition.
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