T48C893 datasheet(18/82 Pages) ATMEL

18 / 82 page

T48C893

Rev. A4, 22-Jan-02

18 (82)

The clock module generates two output clocks. One is the

system clock (SYSCL) and the other the periphery

(SUBCL). The SYSCL can supply the core and the

peripherals and the SUBCL can supply only the

peripherals with clocks. The modes for clock sources are

programmable with the OS1-bit and OS0-bit in the SC-

3.5.2

Oscillator Circuits and External

Clock Input Stage

The T48C893 series consists of four different internal os-

cillators:

two

RC-oscillators,

one

4-MHz

crystal

oscillator, one 32-kHz crystal oscillator and one external

clock input stage.

RC-Oscillator 1 Fully Integrated

For timing insensitive applications, it is possible to use

the fully integrated RC oscillator 1. It operates without

any external components and saves additional costs. The

RC–oscillator 1 center frequency tolerance is better than

±50% over the full temperature and voltage range. The

basic center frequency of the RC-oscillator 1 is

[4.0 MHz The RC oscillator 1 is selected by default

after power–on reset.

oscillator 1

RcOut1

Stop

Control

RcOut1

Osc–Stop

13758

Figure 15. RC-oscillator 1

External Input Clock

The OSC1 can be driven by an external clock source

provided it meets the specified duty cycle, rise and fall

times and input levels. Additionally the external clock

stage contains a supervisory circuit for the input clock.

The supervisor function is controlled via the OS1,

OS0-bit in the SC–register and the CCS–bit in the CM-

than 1 ms and CCS = 0 is set in the CM-register, the

supervisory circuit generates a hardware reset..

Ext. input clock

ExOut

Stop

Ext.

Clock

RcOut1

Osc–Stop

13759

ExIn

CCS

Res

OSC1

OSC2

Clock monitor

Figure 16. External input clock

OS1

OS0

CCS

Supervisor Reset Output

(Res)

enable

disable

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

VDD. In this configuration, the RC-oscillator 2 frequency

can be maintained stable to within a tolerance of

± 15%

over the full operating temperature and a voltage range

VDD from 2.5 V to 6.0 V.

For example: An output frequency at the RC-oscillator 2

of 2 MHz, can be obtained by connecting a resistor

Rext = 360 k

Ω (see figures 17).

oscillator 2

RcOut2

Stop

RcOut2

Osc–Stop

13760

Trim

OSC1

OSC2

ext

Figure 17. RC-oscillator 2

4-MHz Oscillator

The T48C893 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, C3 and C4 are integrated on-chip.

T48C893 数据表(PDF) 18 Page - ATMEL Corporation

T48C893 数据表(HTML) 18 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82

数据表下载

链接网址

T48C893 数据表(PDF) 18 Page - ATMEL Corporation

T48C893 数据表(HTML) 18 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82

数据表 下载

链接网址

数据表下载