MC68HC908LB8CPE Freescale Semiconductor, MC68HC908LB8CPE Datasheet - Page 111

• Manufacturer Part Number: MC68HC908LB8CPE
• Description: IC MCU 8K FLASH 8MHZ 20DIP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908LB8CPE

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Peripherals: LVR, POR, PWM
• Number Of I /o: 18
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 7x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Connectivity: -

Example 2
This example shows how to configure the module to output a frequency of 81.5 kHz, with a deadtime of
10 µs. The system has an HRPCLK of 8 MHz, and the switching frequency must be less than 100 Hz.
If we use 32 steps, simplifying the last equation gives
If we choose STEP[4:0] = 5, the output frequency = 81.5027 kHz.
In this case (using the output of the dual frequency generator as source for the dithering timebase),
To achieve a switching frequency of less than 100 Hz, we must use the 16-bit timebase counter as the
source for the dithering timebase.
To insert a 10 µs deadtime in the output signals, we must calculate the value to store in the HRPDT
register from the following equation.
Freescale Semiconductor
Period (seconds)
P 10:0
Switching Frequency
[
]
P 10:0
+
HRPTB
[
INT
-------------------------------------------- -
STEP 4:0
⎛
⎝
]
------------------ -
2
Switching Frequency
STEP 4:0
---------------------------- -
=
=
SEL[2:0]
2
i.e.
32
=
---------- -
81.5
10
SEL[2:0]
[
98
--------------------------- -
100
–
HRPCLK
[
HRPDT
3
=
=
]
Dead Time
=
STEP 4:0
---------------------------- -
=
MC68HC908LB8 Data Sheet, Rev. 1
10
Output Frequency
----------------------------------------------- -
$62
¥
]
12.2699
⎞
⎠
2
0.1592
¥
SEL
32
=
10
and
[
=
12.2699
2
–
=
10
SEL
6
]
¥
INT
-------------------------------------------- -
=
¥
---------------------- -
100
=
8
¥
32
=
10
=
------------------------- -
HRPCLK
¥
HRPDT
------------------- -
8
8
HRPDT
0.1592
⎛
⎝
¥
–
10
--------------------------------------- -
HRPTB
¥
¥
------------------ -
2
=
STEP 4:0
---------------------------- -
=
6
SEL[2:0]
32
10
8
2
6
32
=
HRPCLK
5.094
80
SEL[2:0]
=
=
6
P 10:0
--------------------
=
8
[
=
[
98.1592
81.5027
-------------------- -
¥
2500
¥
$50
10
=
32
]
2
⎞
⎠
6
5 or 6
SEL
]
+
=
=
INT
-------------------------------------------- -
------------------ -
2
=
0.1592
=
$9C4
SEL[2:0]
32
98
2.5469 kHz
⎛
⎝
STEP 4:0
---------------------------- -
+
2
0.1592
SEL[2:0]
¥
8
[
¥
10
HRP Programming Examples
]
⎞
⎠
6
(EQ 10-21)
(EQ 10-22)
(EQ 10-23)
(EQ 10-24)
(EQ 10-25)
(EQ 10-26)
(EQ 10-27)
(EQ 10-28)
(EQ 10-29)
(EQ 10-30)
(EQ 10-31)
111