t6020m ATMEL Corporation, t6020m Datasheet - Page 16

• Manufacturer Part Number: t6020m
• Description: Low-current Microcontroller For Watchdog Function
• Manufacturer: ATMEL Corporation

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-
register and the CCS-bit in the CM-register.
2.5.2
The T6020M consists of two different internal RC-
oscillators 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
basic center frequency of the RC-oscillator 1 is
f
after power–on reset.
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-
register. If the external input clock fails and CCS = 0 is set
in the CM-register, the supervisory circuit generates a
hardware reset. The input clock has failed if the frequency
is less than 500 kHz for more than 1 ms.
T6020M
16 (54)
O
50% over the full temperature and voltage range. The
[4.0 MHz The RC oscillator 1 is selected by default
Oscillator Circuits and External
Clock Input Stage
Figure 15. RC-oscillator 1
oscillator 1
Control
RC
RcOut1
Stop
Osc–Stop
RcOut1
13758
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
can be maintained stable to within a tolerance of
over the full operating temperature and, voltage range
from V
For example: An output frequency at the RC-oscillator 2
of 1.6 MHz, can be obtained by connecting a resistor
R
2.5.3
The clock management register controls the system clock
divider and synchronization stage. Writing to this register
triggers the synchronization cycle.
OS1
R ext
ext
DD
Clock
1
1
x
Ext.
. In this configuration, the RC-oscillator 2 frequency
= 47 kW (see figure 17).
DD
OS0 CCS
OSC1
OSC1
1
1
0
= 3.5 V to 5.5 V.
Clock Management
Figure 16. External input clock
Figure 17. RC-oscillator 2
0
1
x
Ext. input clock
ExIn
Supervisor Reset Output (Res)
R Trim
Clock monitor
oscillator 2
RC
RcOut2
ExOut
Stop
Stop
disable
disable
enable
Rev. A3, 02-Apr-01
Osc–Stop
Osc–Stop
RcOut2
RcOut1
16532
CCS
Res
10%