AT91SAM7S256D-AU Atmel, AT91SAM7S256D-AU Datasheet - Page 504

• Manufacturer Part Number: AT91SAM7S256D-AU
• Description: ARM Microcontrollers - MCU 256K Flash SRAM 64K ARM based MCU
• Manufacturer: Atmel
• Series: SAM7S256r

Specifications of AT91SAM7S256D-AU

• Rohs: yes
• Core: ARM
• Processor Series: AT91SAM
• Data Bus Width: 16 bit/32 bit
• Maximum Clock Frequency: 55 MHz
• Program Memory Size: 256 KB
• Data Ram Size: 64 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 3 V to 3.6 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: LQFP-64
• Mounting Style: SMD/SMT
• Interface Type: 2-Wire, I2S, SPI, USART
• Length: 7 mm

35.4
35.4.1
35.4.2
Typical Connection
Figure 35-2. Board Schematic to Interface USB Device Peripheral
The USB device transceiver is embedded in the product. A few discrete components are required as follows:
Pullup enable/disable is done through a MOSFET controlled by a PIO. The pullup is enabled when the PIO drives
a 0. Thus PIO default state to 1 corresponds to a pullup disable. Once the pullup is enabled, the host will force a
device reset 100 ms later. Bus powered devices must connect the pullup within 100 ms.
VBUS monitoring is required to detect host connection. VBUS monitoring is done using a standard PIO with inter-
nal pullup disabled. When the host is switched off, it should be considered as a disconnect, the pullup must be
disabled in order to prevent powering the host through the pull-up resistor.
When the host is disconnected and the transceiver is enabled, then DDP and DDM are floating. This may lead to
over consumption. A solution is to connect 330 KΩ pulldowns on DP and DM. These pulldowns do not alter DDP
and DDM signal integrity.
A termination serial resistor must be connected to DP and DM. The resistor value is defined in the electrical speci-
fication of the product (R
• the application detects all device states as defined in chapter 9 of the USB specification;
• to reduce power consumption the host is disconnected
• for line termination.
USB Device Transceiver
VBUS Monitoring
– pullup enable/disable
– VBUS monitoring
PIO
PIO
DDM
DDP
5V Bus Monitoring
Pullup Control
0: Enable
1: Disable
EXT
).
47 K
27 K
R
R
EXT
EXT
330 K
330 K
SAM7S Series [DATASHEET]
3V3
1.5K
2
3
Connector
Type B
6175M–ATARM–26-Oct-12
1
4
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