AT89LP51ED2 Atmel Corporation, AT89LP51ED2 Datasheet - Page 44

• Manufacturer Part Number: AT89LP51ED2
• Manufacturer: Atmel Corporation

Specifications of AT89LP51ED2

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 42
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Adc Channels: 7
• Adc Resolution (bits): 10
• Adc Speed (ksps): 153.8
• Sram (kbytes): 2.25
• Eeprom (bytes): 4096
• Self Program Memory: API
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 4
• Isp: SPI/OCD/UART
• Watchdog: Yes

6.1
44
Crystal Oscillator A
AT89LP51RD2/ED2/ID2 Preliminary
Table 6-1.
Table 6-2.
When enabled, internal inverting oscillator amplifier A is connected between XTAL1A and
XTAL2A for connection to an external quartz crystal or ceramic resonator. The oscillator may
operate in either high-speed or low-power mode. Low-power mode is intended for crystals of 12
MHz or less and consumes less power than the higher speed mode. The configuration as shown
in
capacitors C1 and C2 may be reduced due to the on-chip capacitance of the XTAL1A and
XTAL2A inputs (approximately 10 pF each). When using the crystal oscillator, P4.6 and P4.7 will
have their inputs and outputs disabled. Also, XTAL2A in crystal oscillator mode should not be
used to directly drive a board-level clock without a buffer.
An optional 5 MΩ on-chip resistor can be connected between XTAL1A and GND. This resistor
can improve the startup characteristics of the oscillator especially at higher frequencies. The
resistor can be enabled/disabled with the R1 User Fuse
page
Figure 6-3.
Note:
Figure 6-3
Clock Source A
Clock Source B
190.)
Fuse 1
Fuse 1
1. C1, C2 = 5–15 pF for Crystals
1
1
0
0
1
0
0
applies for both high and low power oscillators. Note that in some cases, external
Clock Source A Settings
Clock Source B Settings (AT89LP51ID2 Only)
Crystal Oscillator A Connections
= 5–15 pF for Ceramic Resonators
Clock Source A
Clock Source B
Fuse 0
Fuse 0
1
0
1
0
–
1
0
C2
C1
Selected Clock Source
High Speed Crystal Oscillator A (f > 12 MHz)
Low Power Crystal Oscillator A (f ≤ 12 MHz)
External Clock on XTAL1A
Internal 8.0 MHz RC Oscillator
Selected Clock Source
Low Frequency Crystal Oscillator B (32 kHz)
External Clock on XTAL1B
Internal 8.0 MHz RC Oscillator
~10 pF
~10 pF
(See “User Configuration Fuses” on
R1
~5 MΩ
3714A–MICRO–7/11