p89v51rb2 NXP Semiconductors, p89v51rb2 Datasheet - Page 9

• Manufacturer Part Number: p89v51rb2
• Description: 8-bit 80c51 5 V Low Power 16/32/64 Kb Flash Microcontroller With 1 Kb Ram
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Table 3.
[1]
[2]
P89V51RB2_RC2_RD2_4
Product data sheet
Symbol
RST
EA
ALE/PROG
n.c.
XTAL1
XTAL2
V
V
DD
SS
ALE loading issue: When ALE pin experiences higher loading (>30 pF) during the reset, the microcontroller may accidentally enter into
modes other than normal working mode. The solution is to add a pull-up resistor of 3 k to 50 k to V
For 6-clock mode, ALE is emitted at
P89V51RB2/RC2/RD2 pin description
Pin
DIP40
9
31
30
-
19
18
40
20
TQFP44
4
29
27
6, 17, 28,
39
15
14
38
16
1
3
of crystal frequency.
PLCC44
10
35
33
1, 12, 23,
34
21
20
44
22
Rev. 04 — 1 May 2007
…continued
Type
I
I
I/O
I/O
I
O
I
I
Description
Reset: While the oscillator is running, a HIGH logic state
on this pin for two machine cycles will reset the device. If
the PSEN pin is driven by a HIGH-to-LOW input transition
while the RST input pin is held HIGH, the device will enter
the external host mode, otherwise the device will enter the
normal operation mode.
External Access Enable: EA must be connected to V
order to enable the device to fetch code from the external
program memory. EA must be strapped to V
program execution. However, Security lock level 4 will
disable EA, and program execution is only possible from
internal program memory. The EA pin can tolerate a high
voltage of 12 V.
Address Latch Enable: ALE is the output signal for
latching the low byte of the address during an access to
external memory. This pin is also the programming pulse
input (PROG) for flash programming. Normally the ALE
is emitted at a constant rate of
and can be used for external timing and clocking. One ALE
pulse is skipped during each access to external data
memory. However, if AO is set to ‘1’, ALE is disabled.
not connected
Crystal 1: Input to the inverting oscillator amplifier and
input to the internal clock generator circuits.
Crystal 2: Output from the inverting oscillator amplifier.
Power supply
Ground
P89V51RB2/RC2/RD2
8-bit microcontrollers with 80C51 core
DD
1
, e.g., for ALE pin.
6
the crystal frequency
© NXP B.V. 2007. All rights reserved.
DD
for internal
9 of 80
SS
[2]
[1]
in