AT91SAM7SE256B-CUR Atmel, AT91SAM7SE256B-CUR Datasheet - Page 273

• Manufacturer Part Number: AT91SAM7SE256B-CUR
• Description: IC ARM7 MCU FLASH 256K 128-LQFP
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91SAM7SE256B-CUR

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 55MHz
• Connectivity: EBI/EMI, I²C, SPI, SSC, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 88
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 32K x 8
• Voltage - Supply (vcc/vdd): 1.65 V ~ 1.95 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Processor Series: SAM7SE256
• Core: ARM7TDMI
• Data Bus Width: 32 bit
• Data Ram Size: 32 KB
• Interface Type: SPI, USB
• Maximum Clock Frequency: 48 MHz
• Number Of Programmable I/os: 88
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Operating Temperature Range: - 40 C to + 85 C
• Processor To Be Evaluated: AT91SAM7SE256B
• Supply Current (max): 60 uA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

28.3.5
28.4
28.4.1
6222F–ATARM–14-Jan-11
Divider and PLL Block
Main Oscillator Bypass
PLL Filter
Slow Clock, so that the frequency of the crystal connected on the Main Oscillator can be
determined.
The user can input a clock on the device instead of connecting a crystal. In this case, the user
has to provide the external clock signal on the XIN pin. The input characteristics of the XIN pin
under these conditions are given in the product electrical characteristics section. The program-
mer has to be sure to set the OSCBYPASS bit to 1 and the MOSCEN bit to 0 in the Main OSC
register (CKGR_MOR) for the external clock to operate properly.
The PLL embeds an input divider to increase the accuracy of the resulting clock signals. How-
ever, the user must respect the PLL minimum input frequency when programming the divider.
Figure 28-3
Figure 28-3. Divider and PLL Block Diagram
The PLL requires connection to an external second-order filter through the PLLRC pin.
28-4
Figure 28-4. PLL Capacitors and Resistors
Values of R, C1 and C2 to be connected to the PLLRC pin must be calculated as a function of
the PLL input frequency, the PLL output frequency and the phase margin. A trade-off has to be
found between output signal overshoot and startup time.
shows a schematic of these filters.
shows the block diagram of the divider and PLL block.
MAINCK
SLCK
C2
Divider
DIV
SAM7SE512/256/32 Preliminary
C1
R
PLLRC
GND
PLLCOUNT
Counter
PLLRC
PLL
MUL
PLL
PLL
OUT
LOCK
PLLCK
Figure
273