P87LPC769 NXP Semiconductors, P87LPC769 Datasheet - Page 35

• Manufacturer Part Number: P87LPC769
• Description: The P87LPC769 is a 20-pin single-chip microcontroller designed forlow pin count applications demanding high-integration, low costsolutions over a wide range of performance requirements
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Reset
The P87LPC769 has an integrated power-on reset circuit which
always provides a reset when power is initially applied to the device.
It is recommended to use the internal reset whenever possible to
save external components and to be able to use pin P1.5 as a
general-purpose input pin.
The P87LPC769 can additionally be configured to use P1.5 as an
external active-low reset pin RST by programming the RPD bit in the
2002 Mar 12
Low power, low price, low pin count (20 pin)
microcontroller with 4 kB OTP 8-bit A/D, and DAC
UCFG1.RPD = 1 (default)
SOFTWARE RESET
POWER MONITOR
SRST (AUXR1.3)
WDTE (UCFG1.7)
MODULE
RPD (UCFG1.6)
RESET
WDT
RST/V
PP
Figure 23. Using pin P1.5 as general purpose input pin or as low-active reset pin
PIN
P1.5
Pin is used as
digital input pin
Internal power-on
Reset active
87LPC769
Figure 24. Block Diagram Showing Reset Sources
UCFG1.RPD = 0
32
User Configuration Register UCFG1 to 0. The internal reset is still
active on power-up of the device. While the signal on the RST pin is
low, the P87LPC769 is held in reset until the signal goes high.
The watchdog timer on the P87LPC769 can act as an oscillator fail
detect because it uses an independent, fully on-chip oscillator.
UCFG1 is described in the System Configuration Bytes section of
this datasheet.
CLOCK
CPU
RST
Pin is used as
active-low reset pin
Internal power-on
Reset active
87LPC769
RESET
TIMING
R
S
Q
SU01384
P87LPC769
CHIP RESET
SU01170
Preliminary data