ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 34

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

9.7
9.8
34
128kHz Internal Oscillator
External Clock
Atmel ATmega48PA/88PA/168PA [Preliminary]
The 128kHz internal Oscillator is a low power Oscillator providing a clock of 128kHz. The fre-
quency is nominal at 3V and 25°C. This clock may be select as the system clock by
programming the CKSEL Fuses to “11” as shown in
Table 9-13.
When this clock source is selected, start-up times are determined by the SUT Fuses as shown
in
Table 9-14.
To drive the device from an external clock source, XTAL1 should be driven as shown in
9-4. To run the device on an external clock, the CKSEL Fuses must be programmed to “0000”
(see
Table 9-15.
Figure 9-4.
Note:
BOD enabled
Fast rising power
Slowly rising power
Note:
Table
Power Conditions
Table
1. Note that the 128kHz oscillator is a very low power clock source, and is not designed for
9-14.
1. If the RSTDISBL fuse is programmed, this start-up time will be increased to
9-15).
high accuracy.
14CK + 4.1ms to ensure programming mode can be entered.
128kHz Internal Oscillator Operating Modes
Start-up Times for the 128kHz Internal Oscillator
Crystal Oscillator Clock Frequency
External Clock Drive Configuration
Nominal Frequency
Frequency
0 - 16MHz
128kHz
EXTERNAL
Power-down and Power-save
SIGNAL
CLOCK
Start-up Time from
PB7
Reserved
(1)
6 CK
6 CK
6 CK
Table
XTAL2
XTAL1
GND
9-13.
Additional Delay from
14CK + 64ms
14CK + 4ms
14CK
Reset
CKSEL3...0
CKSEL3...0
(1)
0011
0000
9223B–AVR–09/11
SUT1...0
00
10
11
Figure
01