mc33981bpna/r2 Freescale Semiconductor, Inc, mc33981bpna/r2 Datasheet - Page 23

• Manufacturer Part Number: mc33981bpna/r2
• Description: Single High-side Switch 4.0 M , Pwm Clock Up To 60khz
• Manufacturer: Freescale Semiconductor, Inc

APPLICATION
targeted automotive applications for the 33981. Conventional
solutions are designed with discrete components that are not
optimized in terms of component board size, protection, and
diagnostics. The 33981 is the right candidate to develop
lighter and more compact units.
consumption by reducing supply voltage, hence the mean
voltage, applied to the motor. The commonly used control
technique is pulse wide modulation (PWM) where the
average voltage is proportional to the duty cycle. Most
applications require a PWM frequency of at least 20 kHz to
avoid audible noise.
when switching the 33981 at 20 kHz with a duty cycle of 80%.
The output voltage (OUT) and current in the motor (I
waveforms are represented.
HOW TO MEASURE ELECTROMAGNETIC
EMISSION ACCORDING TO THE CISPR25
level) is the CISPR25, edited by the International
Electrotechnical Commission. This standard describes the
Analog Integrated Circuit Device Data
Freescale Semiconductor
Figure 21
Engine cooling, air conditioning, and fuel pump are the
DC motor speed adjustment allows optimization of energy
One EMC standard in the automotive world (at system
Figure 22. Current and Voltage waveforms
Figure 21. Typical Application Diagram
illustrates the typical application diagram.
Figure 22
MC33981 ON
Imotor (10A/div)
illustrates typical waveforms
MC33981 OFF
OUT
MOTOR
)
measurement method to measure both conducted and
radiated emission.
CONDUCTED EMISSION MEASUREMENT
device on the battery cable. The test bench is described by
CISPR25 (see
Emission, on page
called Artificial Network (AN), in a given frequency range
(150 kHz to 108 MHz) provides a specified load impedance
for the measurement of disturbance voltages and isolates the
equipment under test (EUT) from the supply in that frequency
range.
conditions just as it must in the vehicle so maximum emission
state occurs. These operating conditions must be clearly
defined in the test plan to ensure that both supplier and
customer are performing identical tests.
pin of the 33981 was connected to an inductive load (0.47 Ω
+ 1.0 mH) switching at 20 kHz with a duty cycle of 80%. The
output current was 17 A continuous.
short as possible. The power supply is 13.5 V.
RADIATED EMISSION MEASUREMENT
measuring the electromagnetic radiation produced by the
equipment under test. CISPR 25 gives the schematic test
bench described in
Emission, on page
several antenna types must be used:
Electrical to Optical
12V Power Supply
Conducted emission is the emission produced by the
The Line Impedance Stabilization Network (LISN), also
The EUT must operate under typical loading and other
For the testing described in this application note, the out
The ground return of the EUT to the chassis must be as
The radiated emission measurement consists of
To measure radiated emission over all frequency ranges,
• 0.15 MHz to 30 MHz: 1.0 m vertical monopole in vertical
• 30 MHz to 200 MHz: a biconical antenna used in vertical
• 200 MHz to 1,000 MHz: a log-periodic antenna used in
Power Supply
BF Generator
Converter
Figure 23. Test Bench for Conducted Emission
polarization.
and horizontal polarization.
vertical and horizontal polarization.
+
-
Figure 23, Test Bench for Conducted
Coaxial Cable
Ground Plane
Contact to
23).
24.
Figure 24, Test Bench for Radiated
Load
LISN
EMC AND EMI RECOMMENDATIONS
Spectrum Analyzer
200
High Side Driver Signal
+
0
200
Non-Conductive
TYPICAL APPLICATIONS
mm
Material
Out
Ground Plane in Copper
EUT
Ground
33981
23