AT89LP6440-20AU Atmel, AT89LP6440-20AU Datasheet - Page 138

• Manufacturer Part Number: AT89LP6440-20AU
• Description: MCU 8051 64K FLASH ISP 44TQFP
• Manufacturer: Atmel
• Series: 89LPr

Specifications of AT89LP6440-20AU

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 38
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 8K x 8
• Ram Size: 4.25K x 8
• Voltage - Supply (vcc/vdd): 2.4 V ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Package: 44TQFP
• Device Core: 8051
• Family Name: 89LP
• Maximum Speed: 20 MHz
• Operating Supply Voltage: 2.5|3.3 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 38
• Interface Type: 2-Wire/SPI
• On-chip Dac: 8-chx10-bit
• Number Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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138
Noise Considerations
AT89LP6440 - Preliminary
be set by hardware while the conversion is in progress. Note that the timer overflow rate must be
slower than the conversion time.
Digital circuitry inside and outside the device generates EMI which might affect the accuracy of
analog measurements. If conversion accuracy is critical, the noise level can be reduced by
applying the following techniques:
Figure 20-7. Example ADC Power Connections (TQFP Package)
• Connect the AV
• Keep analog signal paths as short as possible. Make sure to run analog signals tracks over
• Place the CPU in Idle during a conversion.
• If any Port 0 pins are used as digital outputs, it is essential that these do not switch while a
20-7. Values should be chosen to fit the system. Note this example has a cutoff frequency of
~160kHz and works best for devices operate at 1 MHz or above.
an analog ground plane, and keep them well away from high-speed digital tracks.
conversion is in progress.
39
DD
pin to the digital V
38
37
36
DD
supply voltage via an LC network as shown in
35
34
33
32
31
30
29
28
Analog Ground
P0.4 (ADC4)
P0.5 (ADC5)
P0.6 (ADC6)
P0.7 (ADC7)
GND
Plane
3706A–MICRO–9/09
Figure