參數(shù)資料
型號(hào)： DS89C450
英文描述： Ultra-High-Speed Flash Microcontrollers
中文描述： 超高速閃存微控制器
文件頁(yè)數(shù)： 12/48頁(yè)
文件大?。?/td> 934K
代理商： DS89C450
DS89C430/DS89C440/DS89C450 Ultra-High-Speed Flash Microcontrollers
12 of 48
PIN DESCRIPTION
PIN
PDIP
PLCC
TQFP
NAME
FUNCTION
40
12, 44
6, 38
V
CC
+5V
20
1, 22, 23,
34
16, 17, 28,
39
GND
Logic Ground
9
10
4
RST
External Reset.
The RST input pin is bidirectional and contains a Schmitt Trigger to
recognize external active-high reset inputs. The pin also employs an internal pulldown
resistor to allow for a combination of wire-ORed external reset sources. An RC is not
required for power-up, as the device provides this function internally.
19
21
15
XTAL1
18
20
14
XTAL2
Crystal Oscillators.
These pins provide support for fundamental-mode parallel-resonant
AT-cut crystals. XTAL1 also acts as an input if there is an external clock source in place of
a crystal. XTAL2 serves as the output of the crystal amplifier.
29
32
26
PSEN
Program Store Enable.
This signal is commonly connected to optional external program
memory as a chip enable.
PSEN
provides an active-low pulse and is driven high when
external program memory is not being accessed. In one-cycle page mode 1,
PSEN
remains low for consecutive page hits.
Address Latch Enable.
This signal functions as a clock to latch the external address LSB
from the multiplexed address/data bus on Port 0. This signal is commonly connected to the
latch enable of an external 373-family transparent latch. In default mode, ALE has a pulse
width of 1.5 XTAL1 cycles and a period of four XTAL1 cycles. In page mode, the ALE
pulse width is altered according to the page mode selection. In traditional 8051 mode, ALE
is high when using the EMI reduction mode and during a reset condition. ALE can be
enabled by writing ALEON = 1 (PMR.2). Note that ALE operates independently of ALEON
during external memory accesses. As an alternate mode, this pin (
PROG
) is used to
execute the parallel program function.
30
33
27
ALE/
PROG
39
43
37
P0.0 (AD0)
38
42
36
P0.1 (AD1)
37
41
35
P0.2 (AD2)
36
40
34
P0.3 (AD3)
35
39
33
P0.4 (AD4)
34
38
32
P0.5 (AD5)
33
37
31
P0.6 (AD6)
32
36
30
P0.7 (AD7)
Port 0 (AD0–AD7), I/O.
Port 0 is an open-drain, 8-bit, bidirectional I/O port. As an
alternate function, Port 0 can function as the multiplexed address/data bus to access off-
chip memory. During the time when ALE is high, the LSB of a memory address is
presented. When ALE falls to logic 0, the port transitions to a bidirectional data bus. This
bus is used to read external program memory and read/write external RAM or peripherals.
When used as a memory bus, the port provides weak pullups for logic 1 outputs. The reset
condition of port 0 is tri-state. Pullup resistors are required only when using port 0 as an
I/O port.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS89C450+ENG 制造商:Maxim Integrated Products 功能描述:MCU 8BIT CISC 64KB FLASH 5V 44TQFP - Trays
DS89C450+ENL 制造商:Maxim Integrated Products 功能描述:MCU 8BIT CISC 64KB FLASH 5V 44TQFP - Trays
DS89C450+MNG 制造商:Maxim Integrated Products 功能描述:MCU 8BIT CISC 64KB FLASH 5V 40PDIP - Rail/Tube
DS89C450+MNL 制造商:Maxim Integrated Products 功能描述:MCU 8BIT CISC 64KB FLASH 5V 40PDIP - Rail/Tube
DS89C450+QNL 制造商:Maxim Integrated Products 功能描述:MICRO HI SPD 44PLCC 64K IND PB-FREE - Rail/Tube
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