ATMEGA169P-16MCHR【PDF 201/274 页】MCU AVR 16KB FLASH 16MHZ 64-VQFN

收藏本站

您好，
买卖IC网欢迎您。
请登录
免费注册

买卖IC网

Sheet目录3753

197页 198页 199页 200页 [201页]202页 203页 204页 205页

8018P–AVR–08/10

ATmega169P

8.3

Default Clock Source

The device is shipped with CKSEL = “0010”, SUT = “10”, and CKDIV8 programmed. The default

clock source setting is the Internal RC Oscillator with longest start-up time and an initial system

clock prescaling of 8. This default setting ensures that all users can make their desired clock

source setting using an In-System or Parallel programmer.

8.4

Calibrated Internal RC Oscillator

B default, the Internal RC Oscillator provides an approximate 8 MHz clock. Though voltage and

temperature dependent, this clock can be very accurately calibrated by the user. See Table 28-2

on page 332 and ”Internal Oscillator Speed” on page 365 for more details. The device is shipped

with the CKDIV8 Fuse programmed. See ”System Clock Prescaler” on page 37 for more details.

This clock may be selected as the system clock by programming the CKSEL Fuses as shown in

Table 8-3. If selected, it will operate with no external components. During reset, hardware loads

the pre-programmed calibration value into the OSCCAL Register and thereby automatically cali-

brates the RC Oscillator. The accuracy of this calibration is shown as Factory calibration in Table

28-2 on page 332.

By changing the OSCCAL register from SW, see ”OSCCAL – Oscillator Calibration Register” on

page 38, it is possible to get a higher calibration accuracy than by using the factory calibration.

The accuracy of this calibration is shown as User calibration in Table 28-2 on page 332.

When this Oscillator is used as the chip clock, the Watchdog Oscillator will still be used for the

Watchdog Timer and for the Reset Time-out. For more information on the pre-programmed cali-

bration value, see the section ”Calibration Byte” on page 299.

Notes:

1. The device is shipped with this option selected.

2. The frequency ranges are preliminary values. Actual values are TBD.

3. If 8 MHz frequency exceeds the specification of the device (depends on VCC), the CKDIV8

Fuse can be programmed in order to divide the internal frequency by 8.

When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in

Table 8-4.

Note:

1. The device is shipped with this option selected

Table 8-3.

Internal Calibrated RC Oscillator Operating Modes(1)(3)

Frequency Range(2) (MHz)

CKSEL3:0

7.3 - 8.1

0010

Table 8-4.

Start-up times for the internal calibrated RC Oscillator clock selection

Power Conditions

Start-up Time from Power-

down and Power-save

Additional Delay from

Reset (V

CC = 5.0V)

SUT1:0

BOD enabled

6 CK

14CK

Fast rising power

6 CK

14CK + 4.1 ms

Slowly rising power

6 CK

14CK + 65 ms(1)

Reserved

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

采购需求

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

我的联系方式