DS87C520_1 Datasheet, PDF (3/42 Pages) Dallas Semiconductor – EPROM/ROM High-Speed Micro

DS87C530/DS83C520 BLOCK DIAGRAM Figure 1
DS87C520/DS83C520
PIN DESCRIPTION Table 1
DIP
PLCC
TQFP
40
44
38
20
22,23,
16, 17,
1
39
9
10
4
18
20
14
19
21
15
29
32
26
SIGNAL
NAME
V_CC
GND
DESCRIPTION
V_CC - +5V
GND - Digital circuit ground.
RST
XTAL2
XTAL1
PSEN
RST - 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.
XTAL1, XTAL2 - The crystal oscillator pins XTAL1 and
XTAL2 provide support for parallel resonant, AT cut
crystals. XTAL1 acts also as an input if there is an external
clock source in place of a crystal. XTAL2 serves as the
output of the crystal amplifier.
PSEN - Output. The Program Store Enable output. This
signal is commonly connected to optional external ROM
memory as a chip enable. PSEN will provide an active
low pulse and is driven high when external ROM is not
being accessed.
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