AT83C5135 Atmel Corporation, AT83C5135 Datasheet - Page 14

• Manufacturer Part Number: AT83C5135
• Manufacturer: Atmel Corporation

Specifications of AT83C5135

• Max. Operating Frequency: 32 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Sram (kbytes): 1.25
• Eeprom (bytes): 512
• Operating Voltage (vcc): 2.7 to 3.6
• Timers: 4
• Mask Rom (kbytes): 16
• Watchdog: Yes

6.3
6.3.1
Figure 6-3.
14
PLL
AT83C5134/35/36
PLL Description
CLOCK
OSC
PLL Block Diagram and Symbol
N divider
In order to optimize the power consumption, the oscillator inverter is inactive when the PLL out-
put is not selected for the USB device.
Figure 6-2.
The AT83C5134/35/36 PLL is used to generate internal high frequency clock (the USB Clock)
synchronized with an external low-frequency (the Peripheral Clock). The PLL clock is used to
generate the USB interface clock. Figure 6-3 shows the internal structure of the PLL.
The PFLD block is the Phase Frequency Comparator and Lock Detector. This block makes the
comparison between the reference clock coming from the N divider and the reverse clock com-
ing from the R divider and generates some pulses on the Up or Down signal depending on the
edge position of the reverse clock. The PLLEN bit in PLLCON register is used to enable the
clock generation. When the PLL is locked, the bit PLOCK in PLLCON register (see Figure 6-3) is
set.
The CHP block is the Charge Pump that generates the voltage reference for the VCO by inject-
ing or extracting charges from the external filter connected on PLLF pin (see Figure 6-4). Value
of the filter components are detailed in the Section “DC Characteristics”.
The VCO block is the Voltage Controlled Oscillator controlled by the voltage V
the charge pump. It generates a square wave signal: the PLL clock.
N3:0
Crystal Connection
PLLCON.1
PLLCON.0
PLOCK
PLLEN
USBclk
PFLD
Down
=
Up
OSCclk
---------------------------------------------- -
R divider
VSS
R3:0
PLLF
CHP
N
+
×
1
(
C1
C2
R
+
Vref
1
)
Q
VCO
X1
X2
USB Clock Symbol
USB Clock
CLOCK
USB
REF
7683C–USB–11/07
produced by