AT89LP51ID2 Atmel Corporation, AT89LP51ID2 Datasheet - Page 46

• Manufacturer Part Number: AT89LP51ID2
• Manufacturer: Atmel Corporation

Specifications of AT89LP51ID2

• 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

6.5
6.6
46
External Clock Source B (AT89LP51ID2)
Dual Oscillator Support (AT89LP51ID2)
AT89LP51RD2/ED2/ID2 Preliminary
Figure 6-5.
Note:
The external clock option of AT89LP51ID2 disables the oscillator amplifier B and allows XTAL1B
to be driven directly by an external clock source as shown in
unconnected or used as general purpose I/O P4.2.
Figure 6-6.
The AT89LP51ID2 has the ability to switch between two different selectable system clock
sources under software control as shown in
Several operating modes are available and programmable by software:
Selection of which oscillator drives the system clock is controlled by the CKS bit in CKSEL. In
order to switch to a different oscillator, that oscillator must be enabled with the OscAEn or Osc-
• OSCA can be a high frequency crystal, external clock or the internal 8 MHz oscillator
• OSCB can be a low frequency crystal, external clock or the internal 8 MHz oscillator
• Switch system clock source from OSCA to OSCB and vice-versa
• Power down OSCA or OSCB to reduce consumption
• Boot from a fast responding, less accurate oscillator and switch later to a more accurate but
slow to stabilize oscillator.
1. C1, C2 = 10–20 pF for Crystals
Crystal Oscillator B Connections
External Clock A Drive Configuration
= 10–20 pF for Ceramic Resonators
OSCILLA T OR
EXTERNAL
NC GPIO
C2
C1
SIGNAL
Figure 6-2 on page
XTAL2B
XTAL1B
XT AL2B (P4.2)
XT AL1B (P1.0)
GND
~10 pF
~10 pF
Rd
Figure
43.
6-6. XTAL2B may be left
3714A–MICRO–7/11