AT90PWM3B-16SUR Atmel, AT90PWM3B-16SUR Datasheet - Page 38
![MCU AVR 8K FLASH 16MHA 32SOIC](/photos/7/29/72992/313-32-soic_sml.jpg)
AT90PWM3B-16SUR
Manufacturer Part Number
AT90PWM3B-16SUR
Description
MCU AVR 8K FLASH 16MHA 32SOIC
Manufacturer
Atmel
Series
AVR® 90PWM Lightingr
Datasheet
1.AT90PWM3B-16SU.pdf
(361 pages)
Specifications of AT90PWM3B-16SUR
Core Processor
AVR
Core Size
8-Bit
Speed
16MHz
Connectivity
SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
27
Program Memory Size
8KB (8K x 8)
Program Memory Type
FLASH
Eeprom Size
512 x 8
Ram Size
512 x 8
Voltage - Supply (vcc/vdd)
2.7 V ~ 5.5 V
Data Converters
A/D 11x10b; D/A 1x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 105°C
Package / Case
32-SOIC (7.5mm Width)
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
- Current page: 38 of 361
- Download datasheet (7Mb)
7.10.1
38
AT90PWM2/3/2B/3B
Clock Prescaler Register – CLKPR
When switching between prescaler settings, the System Clock Prescaler ensures that no
glitches occurs in the clock system. It also ensures that no intermediate frequency is higher than
neither the clock frequency corresponding to the previous setting, nor the clock frequency corre-
sponding to the new setting. The ripple counter that implements the prescaler runs at the
frequency of the undivided clock, which may be faster than the CPU's clock frequency. Hence, it
is not possible to determine the state of the prescaler - even if it were readable, and the exact
time it takes to switch from one clock division to the other cannot be exactly predicted. From the
time the CLKPS values are written, it takes between T1 + T2 and T1 + 2 * T2 before the new
clock frequency is active. In this interval, 2 active clock edges are produced. Here, T1 is the pre-
vious clock period, and T2 is the period corresponding to the new prescaler setting.
To avoid unintentional changes of clock frequency, a special write procedure must be followed
to change the CLKPS bits:
1. Write the Clock Prescaler Change Enable (CLKPCE) bit to one and all other bits in
2. Within four cycles, write the desired value to CLKPS while writing a zero to CLKPCE.
Interrupts must be disabled when changing prescaler setting to make sure the write procedure is
not interrupted.
• Bit 7 – CLKPCE: Clock Prescaler Change Enable
The CLKPCE bit must be written to logic one to enable change of the CLKPS bits. The CLKPCE
bit is only updated when the other bits in CLKPR are simultaniosly written to zero. CLKPCE is
cleared by hardware four cycles after it is written or when CLKPS bits are written. Rewriting the
CLKPCE bit within this time-out period does neither extend the time-out period, nor clear the
CLKPCE bit.
• Bits 3..0 – CLKPS3..0: Clock Prescaler Select Bits 3 - 0
These bits define the division factor between the selected clock source and the internal system
clock. These bits can be written run-time to vary the clock frequency to suit the application
requirements. As the divider divides the master clock input to the MCU, the speed of all synchro-
nous peripherals is reduced when a division factor is used. The division factors are given in
Table
The CKDIV8 Fuse determines the initial value of the CLKPS bits. If CKDIV8 is unprogrammed,
the CLKPS bits will be reset to “0000”. If CKDIV8 is programmed, CLKPS bits are reset to
“0011”, giving a division factor of 8 at start up. This feature should be used if the selected clock
source has a higher frequency than the maximum frequency of the device at the present operat-
ing conditions. Note that any value can be written to the CLKPS bits regardless of the CKDIV8
Fuse setting. The Application software must ensure that a sufficient division factor is chosen if
Bit
Read/Write
Initial Value
CLKPR to zero.
7-12.
CLKPCE
R/W
7
0
R
6
–
0
R
5
–
0
R
4
–
0
CLKPS3
R/W
3
CLKPS2
See Bit Description
R/W
2
CLKPS1
R/W
1
CLKPS0
R/W
0
4317J–AVR–08/10
CLKPR
Related parts for AT90PWM3B-16SUR
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
![AT90PWM3B](/images/manufacturer_photos/0/0/79/atmel_corporation_tmb.jpg)
Part Number:
Description:
Manufacturer:
Atmel Corporation
Datasheet:
![AT90PWM3B-16SU](/photos/7/29/72992/313-32-soic_tmb.jpg)
Part Number:
Description:
IC MCU AVR RISC 8K FLASH 32-SOIC
Manufacturer:
Atmel
Datasheet:
![AT90PWM3B-16MU](/images/manufacturer_photos/0/0/78/atmel_tmb.jpg)
Part Number:
Description:
IC MCU AVR RISC 8K FLASH 32-QFN
Manufacturer:
Atmel
Datasheet:
![AT90PWM3-16MQ](/photos/12/13/121309/313-32-qfn_tmb.jpg)
Part Number:
Description:
IC AVR MCU FLASH 8K 32QFN
Manufacturer:
Atmel
Datasheet:
![AT90PWM3-16SQ](/photos/7/29/72992/313-32-soic_tmb.jpg)
Part Number:
Description:
IC AVR MCU FLASH 8K 32SOIC
Manufacturer:
Atmel
Datasheet:
![AT90PWM3-16MQT](/images/manufacturer_photos/0/0/78/atmel_tmb.jpg)
Part Number:
Description:
MCU AVR 8K FLASH 16MHZ 32-QFN
Manufacturer:
Atmel
Datasheet:
![ATSTK600](/photos/9/20/92038/atstk600_tmb.jpg)
Part Number:
Description:
DEV KIT FOR AVR/AVR32
Manufacturer:
Atmel
Datasheet:
![U641B](/images/manufacturer_photos/0/0/79/atmel_corporation_tmb.jpg)
Part Number:
Description:
INTERVAL AND WIPE/WASH WIPER CONTROL IC WITH DELAY
Manufacturer:
ATMEL Corporation
Datasheet:
![U4082B](/images/manufacturer_photos/0/0/79/atmel_corporation_tmb.jpg)
Part Number:
Description:
Low-Voltage Voice-Switched IC for Hands-Free Operation
Manufacturer:
ATMEL Corporation
Datasheet:
![U4089B](/images/manufacturer_photos/0/0/79/atmel_corporation_tmb.jpg)
Part Number:
Description:
MONOLITHIC INTEGRATED FEATUREPHONE CIRCUIT
Manufacturer:
ATMEL Corporation
Datasheet:
![U4255BM-M](/images/manufacturer_photos/0/0/79/atmel_corporation_tmb.jpg)
Part Number:
Description:
AM-FM Receiver IC U4255BM-M
Manufacturer:
ATMEL Corporation
Datasheet:
![U4089B-P](/images/manufacturer_photos/0/0/79/atmel_corporation_tmb.jpg)
Part Number:
Description:
Monolithic Integrated Feature Phone Circuit
Manufacturer:
ATMEL Corporation
Datasheet:
![TDA4470](/images/manufacturer_photos/0/0/79/atmel_corporation_tmb.jpg)
Part Number:
Description:
Multistandard Video-IF and Quasi Parallel Sound Processing
Manufacturer:
ATMEL Corporation
Datasheet: