AT89LP52 Atmel Corporation, AT89LP52 Datasheet - Page 32
![no-image](/images/manufacturer_photos/0/0/79/atmel_corporation_sml.jpg)
AT89LP52
Manufacturer Part Number
AT89LP52
Description
Manufacturer
Atmel Corporation
Datasheet
1.AT89LP51.pdf
(117 pages)
Specifications of AT89LP52
Flash (kbytes)
8 Kbytes
Max. Operating Frequency
20 MHz
Cpu
8051-1C
Max I/o Pins
36
Uart
1
Sram (kbytes)
0.25
Eeprom (bytes)
256
Self Program Memory
IAP
Operating Voltage (vcc)
2.4 to 5.5
Timers
3
Isp
SPI
Watchdog
Yes
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
AT89LP52-20AU
Manufacturer:
Atmel
Quantity:
250
Company:
Part Number:
AT89LP52-20JU
Manufacturer:
Atmel
Quantity:
110
Company:
Part Number:
AT89LP52-20MU
Manufacturer:
Atmel
Quantity:
490
7. Reset
7.1
32
Power-on Reset
AT89LP51/52
During reset, all I/O Registers are set to their initial values, the port pins are set to their default
mode, and the program starts execution from the Reset Vector, 0000H. The AT89LP51/52 has
five sources of reset: power-on reset, brown-out reset, external reset, watchdog reset, and soft-
ware reset.
A Power-on Reset (POR) is generated by an on-chip detection circuit. The detection level V
is nominally 1.4V. The POR is activated whenever V
cuit can be used to trigger the start-up reset or to detect a major supply voltage failure. The POR
circuit ensures that the device is reset from power-on. A power-on sequence is shown in
7-1. When V
lasting t
how long the device is kept in POR after V
until after V
activated again, without any delay, when V
Reset (i.e. a cold reset) will set the POF flag in PCON. The internally generated reset can be
extended beyond the power-on period by holding the RST pin active longer than the time-out.
Figure 7-1.
Note:
The start-up timer delay is user-configurable with the Start-up Time User Fuses and depends on
the clock source
after a Brown-out Reset or when waking up from Power-down during internally timed mode. The
start-up delay should be selected to provide enough settling time for V
source. The device operating environment (supply voltage, frequency, temperature, etc.) must
meet the minimum system requirements before the device exits reset and starts normal opera-
tion. The RST pin may be held active externally until these conditions are met.
POR
t
POR
Time-out
DD
is started. When the initialization sequence completes, the start-up timer determines
Internal
Internal
is approximately 143 µs ± 5%.
DD
Reset
Reset
reaches the Brown-out Detector (BOD) threshold voltage V
Power-on Reset Sequence
POL
RST
RST
V
reaches the Power-on Reset threshold voltage V
(Table
DD
t
POR
7-1). The Start-Up Time fuses also control the length of the start-up time
V
POR
V
BOD
(RST Controlled Externally)
DD
DD
t
SUT
falls below the POR threshold level. A Power-on
rise. The start-up timer does not begin counting
DD
(POL Tied to VCC)
(RST Tied to GND)
is below the detection level. The POR cir-
POR
, an initialization sequence
DD
V
IL
BOD
and the selected clock
t
RHD
. The POR signal is
3709D–MICRO–12/11
Figure
POR