DS87C520-WCL+ Maxim Integrated, DS87C520-WCL+ Datasheet - Page 4

• Manufacturer Part Number: DS87C520-WCL+
• Manufacturer: Maxim Integrated

Figure 1. Block Diagram
PIN DESCRIPTION
DIP
40
20
18
19
29
9
DS87C520/
DS83C520
1, 22, 23
PLCC
PIN
44
10
20
21
32
16, 17, 39
TQFP
38
14
15
26
4
XTAL2
XTAL1
NAME
PSEN
GND
RST
V
CC
4 of 45
Positive Supply Voltage. +5V
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 if
there is an external clock source in place of a crystal. XTAL2
serves as the output of the crystal amplifier.
Program Store-Enable Output. This active-low signal is
commonly connected to optional external ROM memory as a chip
enable. PSEN provides an active-low pulse and is driven high
when external ROM is not being accessed.
FUNCTION