AT89LP6440-20PU Atmel, AT89LP6440-20PU Datasheet - Page 78

• Manufacturer Part Number: AT89LP6440-20PU
• Description: MCU 8051 64K FLASH ISP 40PDIP
• Manufacturer: Atmel
• Series: 89LPr

Specifications of AT89LP6440-20PU

• 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: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 13-9. Non-overlapping Waveforms Using Symmetrical PWM
13.4.2.1
13.4.2.2
78
AT89LP6440 - Preliminary
(Non-Inverted) CCB
{RCAP2H,RCA2L}
Phase and Frequency Correct PWM
Phase Correct PWM
(Inverted) CCA
{CCAH,CCAL}
{CCBH,CCBL}
center-aligned around the timer equal to TOP point. Symmetrical PWM may be used to generate
non-overlapping waveforms.
The TOP value in RCAP2L and RCAP2H is double buffered such that the output frequency is
only updated at the underflow. The channel data register (CCxL, CCxH) is also double-buffered
to prevent glitches. The output frequency and duty cycle for symmetrical PWM are given by the
following equations:
The extreme compare values represent special cases when generating a PWM waveform. If the
compare value is set equal to (or greater than) TOP, the output will remain high or low for non-
inverting and inverting modes, respectively. If the compare value is set to MIN (0000H), the out-
put will remain low or high for non-inverting and inverting modes, respectively.
When T2CM
this mode the compare value double buffer is only updated when the timer equals MIN (under-
flow). This guarantees that the resulting waveform is always symmetrical around the TOP value
as shown in
TF2 interrupt flag is only set at underflow.
When T2CM
compare value double buffer is updated when the timer equals MIN (underflow) and TOP (over-
flow). The resulting waveform may not be completely symmetrical around the TOP value as
shown in
However, this allows the pulses to be weighted toward one edge or another. The TF2 interrupt
flag is set at both underflow and overflow.
Figure 13-11
1-0
1-0
Figure 13-10
Inverting:
= 10B the Symmetrical PWM operates in phase and frequency correct mode. In
= 11B the Symmetrical PWM operates in phase correct mode. In this mode the
Non-Inverting:
CP/RL2 = 0, T2CM
because the up and down count compare values may not be identical.
because the up and down count compare values are identical. The
Duty Cycle
f
OUT
=
---------------------------------------------------------------- -
2
×
Duty Cycle
Oscillator Frequency
1-0
=
{
RCAP2H RCAP2L
100%
= 10B, DCEN = 0
×
=
,
{
-------------------------------------------------------------------------------------------------- -
RCAP2H RCAP2L
100%
{
×
}
RCAP2H RCAP2L
,
------------------------------------------------------
{
×
RCAP2H RCAP2L
-------------------- -
TPS
{
CCxH CCxL
1
,
+
}
1
,
,
–
{
CCxH CCxL
}
}
,
}
}
3706A–MICRO–9/09