ATAM894 datasheet(18/97 Pages) ATMEL

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4679D–4BMCU–05/05

ATAM894

5.5.2.3

RC-oscillator 2 with External Trimming Resistor

The RC-oscillator 2 is a high resolution trimmable oscillator whereby the oscillator frequency can

be trimmed with an external resistor between OSC1 and V

DD. In this configuration, the RC-oscil-

lator 2 frequency can be maintained stable with a tolerance of ±15% over the full operating

temperature and a voltage range V

DD from 2.5V to 6.0V.

For example: An output frequency at the RC-oscillator 2 of 2 MHz can be obtained by connect-

ing a resistor R

ext = 360 kΩ (see Figure 5-15).

Figure 5-15.

RC-oscillator 2

5.5.2.4

4-MHz Oscillator

The ATAM894 4-MHz oscillator options need a crystal or ceramic resonator connected to the

OSC1 and OSC2 pins to establish oscillation. All the necessary oscillator circuitry, with the

exception of the actual crystal, resonator, C

3 and C4 are integrated on-chip.

Figure 5-16.

4-MHz Crystal Oscillator

Note:

Both, the 4-MHz and the 32-kHz crystal oscillator, use an integrated 14 stage divider circuit to sta-

bilize oscillation before the oscillator output is used as system clock. This results in an additional

delay of about 4 ms for the 4-MHz crystal and about 500 ms for the 32-kHz crystal.

Table 5-5.

Supervisor Function Control Bits

OS1

OS0

CCS

Supervisor Reset Output (Res)

Enable

Disable

RC-oscillator 2

RcOut2

Stop

RcOut2

Osc-Stop

Trim

OSC1

OSC2

ext

4-MHz

oscillator

4Out

OSC1

OSC2

Oscin

Oscout

XTAL

4 MHz

configurable

Stop

Osc-Stop

ATAM894 Datasheet(PDF) 18 Page - ATMEL Corporation

ATAM894 Datasheet(HTML) 18 Page - ATMEL Corporation

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