AT89C5131A-M Atmel Corporation, AT89C5131A-M Datasheet - Page 15

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AT89C5131A-M

Manufacturer Part Number
AT89C5131A-M
Description
Manufacturer
Atmel Corporation
Datasheets

Specifications of AT89C5131A-M

Flash (kbytes)
32 Kbytes
Max. Operating Frequency
48 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)
1024
Self Program Memory
API
Operating Voltage (vcc)
2.7 to 5.5
Timers
4
Isp
UART/USB
Watchdog
Yes
5.3
5.3.1
Figure 5-3.
4337K–USB–04/08
PLL
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 5-2.
The AT89C5130A/31A-M 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 5-3 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 5-3) 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 5-4). 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
AT89C5130A/31A-M
USB Clock Symbol
USB Clock
CLOCK
USB
REF
produced by
15

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