p87lpc764hdh NXP Semiconductors, p87lpc764hdh Datasheet - Page 28

• Manufacturer Part Number: p87lpc764hdh
• Description: Low Power, Low Price, Low Pin Count 20 Pin Microcontroller With 4 Kbyte Otp
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Low Voltage EPROM Operation
The EPROM array contains some analog circuits that are not
required when V
greater than 4 V. The LPEP bit (AUXR.4), when set by software, will
power down these analog circuits resulting in a reduced supply
current. LPEP is cleared only by power-on reset, so it may be set
ONLY for applications that always operate with V
Reset
The P87LPC764 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
2003 Sep 03
Low power, low price, low pin count (20 pin)
microcontroller with 4 kbyte OTP
UCFG1.RPD = 1 (default)
SOFTWARE RESET
POWER MONITOR
SRST (AUXR1.3)
DD
WDTE (UCFG1.7)
MODULE
RPD (UCFG1.6)
is less than 4 V, but are required for a V
RESET
WDT
RST/V
PP
Figure 20. 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
87LPC764
Figure 21. Block Diagram Showing Reset Sources
DD
less than 4 V.
DD
UCFG1.RPD = 0
27
external active-low reset pin RST by programming the RPD bit in the
save external components and to be able to use pin P1.5 as a
general-purpose input pin.
The P87LPC764 can additionally be configured to use P1.5 as an
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 P87LPC764 is held in reset until the signal goes high.
The watchdog timer on the LPC764 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
87LPC764
RESET
TIMING
R
S
Q
SU01169
P87LPC764
CHIP RESET
SU01170
Product data