AT83EB5114 Atmel Corporation, AT83EB5114 Datasheet - Page 12

• Manufacturer Part Number: AT83EB5114
• Manufacturer: Atmel Corporation

Specifications of AT83EB5114

• Max. Operating Frequency: 24 MHz
• Cpu: 8051-12C
• Max I/o Pins: 11
• Adc Channels: 6
• Adc Resolution (bits): 10
• Adc Speed (ksps): 50
• Sram (kbytes): 0.25
• Eeprom (bytes): 256
• Operating Voltage (vcc): 3.0 to 3.6
• Timers: 4
• Mask Rom (kbytes): 4
• Watchdog: Yes

Crystal Oscillator: OSCA
High Accurate RC Oscillator:
OSCB
Low Power Consumption
Oscillator: OSCC
Clock Selector
X2 Feature
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AT89/83EB5114
The crystal oscillator uses two external pins, XTAL1 for input and XTAL2 for output.
OSCAEN in OSCCON register is an enable signal for the crystal oscillator or for the
external oscillator input that can be provided on XTAL1.
The high accuracy RC oscillator needs external R and C components to assure the
proper accuracy; its typical frequency is 12 MHz. Frequency accuracy is a function of
external R and C accuracy. It is recommended to use 0.5% or better for R and 1% for C
components. (Typical values are R = 49.9 K and C = 560 pF)
This oscillator has two modes.
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OSCBEN and LCKEN are in the OSCCON register.
The low power consumption RC oscillator doesn’t need any external components. More-
over its consumption is very low. Its typical frequency is 14 MHz. Note that this on-chip
oscillator has a +/- 40% frequency tolerance and may not be suitable for use in certain
applications.
OSCC is set by OSCCEN bit in OSCCON.
CKS1 and CKS0 bits in CKSEL register are used to select the clock source.
OSCCEN bit in OSCCON register is used to enable the low power consumption RC
oscillator.
OSCBEN bit in OSCCON register is used to enable the high accurate RC oscillator.
OSCAEN bit in OSCCON register is used to enable the crystal oscillator or the external
oscillator input.
The AT8xEB5114 core needs only 6 clock periods per machine cycle. This feature
called ”X2” provides the following advantages:
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In order to keep the original C51 compatibility, a divider by 2 is inserted between the
XTAL1 signal and the main clock input of the core (phase generator). This divider may
be enabled or disabled by software.
OSCBEN = 1 and LCKEN = 0: Standard accuracy mode(Typical frequency 12 MHz)
OSCBEN = 1 and LCKEN = 1: High accuracy mode (Typical frequency 12 MHz).
The OSCB oscillator is based on a low frequency RC oscillator and a VCO. When
locked, the oscillator frequency is defined by the following formula:
F = 3*[OSCBFA+1]/(R.C). with C including parasitic capacitances.
Because the oscillator is based on a PLL, it needs several periods to reach its final
accuracy. As soon as this accuracy is reached, the OSCBRY bit in OSCCON
register is set by hardware.
The internal frequency is locked on the external RC time constant. So it is possible
to adjust frequency by lower than 1% steps with the OSCBFA register. However the
frequency adjustment is limited to +/-15% around 12 MHz.
The frequency can be adjusted until 15% around 12 MHz by OSCBFA Register.
Divides frequency crystals by 2 (cheaper crystals) while keeping same CPU power.
Saves power consumption while keeping same CPU power (oscillator power
saving).
Saves power consumption by dividing dynamically the operating frequency by 2 in
operating and idle modes.
Increases CPU power by 2 while keeping same crystal frequency.
4311C–8051–02/08