DS89C420-QCL Maxim Integrated Products, DS89C420-QCL Datasheet - Page 13

• Manufacturer Part Number: DS89C420-QCL
• Description: IC MCU ULTRA 33MHZ HP 44-PLCC
• Manufacturer: Maxim Integrated Products
• Series: 89Cr

Specifications of DS89C420-QCL

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 33MHz
• Connectivity: EBI/EMI, SIO, UART/USART
• Peripherals: Power-Fail Reset, WDT
• Number Of I /o: 32
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 44-LCC, 44-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -

PIN DESCRIPTION (continued)
10–17
DIP
21
22
23
24
25
26
27
28
10
11
12
13
14
15
16
17
31
11, 13–19
PLCC
PIN
24
25
26
27
28
29
30
31
11
13
14
15
16
17
18
19
35
5, 7–13
PDIP
18
19
20
21
22
23
24
25
10
11
12
13
29
5
7
8
9
P2.2 (A10)
P2.3 (A11)
P2.4 (A12)
P2.5 (A13)
P2.6 (A14)
P2.7 (A15)
P3.0–P3.7
P2.0 (A8)
P2.1 (A9)
NAME
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
EA
Port 2 (A8–15), I/O. Port 2 is an 8-bit, bidirectional I/O port. The reset
condition of port 2 is logic high. In this state, a weak pullup holds the port high.
This condition also serves as an input mode, since any external circuit that
writes to the port overcomes the weak pullup. When software writes a 0 to any
port pin, the DS89C420 activates a strong pulldown that remains on until
either a 1 is written or a reset occurs. Writing a 1 after the port has been at 0
causes a strong transition driver to turn on, followed by a weaker sustaining
pullup. Once the momentary strong driver turns off, the port again becomes
both the output high and input state. As an alternate function, port 2 can
function as the MSB of the external address bus when reading external
program memory and read/write external RAM or peripherals. In page mode
1, port 2 provides both the MSB and LSB of the external address bus; in page
mode 2, it provides the MSB and data.
Port 3, I/O. Port 3 functions as both an 8-bit, bidirectional I/O port and an
alternate functional interface for external interrupts, serial port 0, timer 0 and 1
inputs, and RD and WR strobes. The reset condition of port 3 is with all bits at
logic 1. In this state, a weak pullup holds the port high. This condition also
serves as an input mode, since any external circuit that writes to the port
overcomes the weak pullup. When software writes a 0 to any port pin, the
DS89C420 activates a strong pulldown that remains on until either a 1 is
written or a reset occurs. Writing a 1 after the port has been at 0 causes a
strong transition driver to turn on, followed by a weaker sustaining pullup.
Once the momentary strong driver turns off, the port again becomes both the
output high and input state. The alternate modes of Port 3 are outlined below.
External Access. Allows selection of internal or external program memory.
Connect to ground to force the DS89C420 to use an external memory-
program memory. The internal RAM is still accessible as determined by
register settings. Connect to V
PORT
P3.0
P3.2
P3.3
P3.6
P3.7
13 of 47
P3.1
P3.4
P3.5
ALTERNATE
RXD0
TXD0
INT0
INT1
WR
RD
T1
T0
CC
to use internal flash memory.
FUNCTION
External Data Memory Read Strobe
External Data Memory Write Strobe
Timer 1 External Input
Timer 0 External Input
Serial Port 0 Transmit
Serial Port 0 Receive
External Interrupt 0
External Interrupt 1
FUNCTION