80C31X2 Datasheet, PDF (11/62 Pages) NXP Semiconductors – 80C51 8-bit microcontroller family 4K/8K/16K/32K ROM/OTP 128B/256B RAM low voltage 2.7 to 5.5 V, low power, high speed 30/33 MHz

Philips Semiconductors
80C51 8-bit microcontroller family
4K/8K/16K/32K ROM/OTP, low voltage (2.7 to 5.5 V),
low power, high speed (30/33 MHz)
Product data
P80C3xX2; P80C5xX2;
P87C5xX2
PIN NUMBER
MNEMONIC DIP PLCC LQFP TSSOP TYPE NAME AND FUNCTION
PSEN
29
32
26
18
O Program Store Enable: The read strobe to external program memory. When the
device is executing code from the external program memory, PSEN is activated
twice each machine cycle, except that two PSEN activations are skipped during
each access to external data memory. PSEN is not activated during fetches from
internal program memory.
EA/V_PP
31
35
29
20
I External Access Enable/Programming Supply Voltage: EA must be externally held low to enable
the device to fetch code from external program memory locations 0000H to
0FFFH/1FFFH/3FFFH/7FFFH. If EA is held high, the device executes from internal program memory
unless the program counter contains an address greater than the on-chip ROM/OTP. This pin also
receives the 12.75 V programming supply voltage (V_PP) during EPROM programming. If security bit
1 is programmed, EA will be internally latched on Reset.
XTAL1
19
21
15
8
I Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock
generator circuits.
XTAL2
18
20
14
7
O Crystal 2: Output from the inverting oscillator amplifier.
NOTES:
To avoid “latch-up” effect at power-on, the voltage on any pin at any time must not be higher than V_CC + 0.5 V or V_SS – 0.5 V, respectively.
1. Absent in the TSSOP38 package.
2003 Jan 24
11