MC33993DWB Freescale Semiconductor, MC33993DWB Datasheet - Page 21

• Manufacturer Part Number: MC33993DWB
• Description: IC SWITCH I/O INTERFACE 32-SOIC
• Manufacturer: Freescale Semiconductor

Specifications of MC33993DWB

• Applications: *
• Interface: *
• Voltage - Supply: *
• Package / Case: 32-SOIC (7.5mm Width)
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

grounded and brought back to the module ground, as
illustrated in
impedance of the sensor, the analog voltage on the input will
represent the position of the sensor.
current to an analog sensor may induce error due to the
accuracy of the current source. For this reason, a ratiometric
conversion must be considered. Using two current sources
(one for the sensor and one to set the reference voltage to the
A / D converter) will yield a maximum error (owing to the
33993) of 4%.
calibration. In this example, we use the resistor values from
Figure 13
other. The user may use the module end-of-line tester to
calculate the error in the A / D conversion. By placing a
2.0 kΩ, 0.1% resistor in the end-of-line test equipment and
assuming a perfect 2.0 mA current source from the 33993, a
calculated A / D
conversion may be obtained. Using the equation yields the
following:
Analog Integrated Circuit Device Data
Freescale Semiconductor
VBAT
VBAT
Analog Sensor
or Analog Switch
To read a potentiometer sensor, the wiper should be
Using the Analog feature to provide 2.0 mA of pull-up
Higher accuracy may be achieved through module level
R
2.0 mA
1
I
1
Figure 13. Analog Ratiometric Conversion
and assume the current sources are 4% from each
SG12
SG13
Figure
SP0
SP1
SG0
SG1
SP7
2.0 mA
I
2
2.39 kΩ
16
mA
mA
16
0.1%
V
V
13. With the wiper changing the
PWR
PWR
4.54 V to 5.02 V
33993
V
V
PWR
PWR
2.0
mA
2.0
mA
R
2
WAKE
AMUX
SCLK
V
V
PWR
INT
SO
CS
DD
SI
V
DD
MOSI
SCLK
CS
MISO
INT
V
V
AN0
Analog
REF(H)
REF(L)
MCU
Ports
(neglecting the resistor tolerance and AMUX input offset
voltage). Now we can calculate the count value induced by
the mismatch in current sources. From a sample device the
maximum current source was measured at 2.05 mA and
minimum current source was measured at 1.99 mA. This
yields 3% error in A / D conversion. The A / D measurement
will be as follows:
correction factor of 1.03 may be used to correct the value:
memory and used in the A / D calculation for the specific input.
Each input used as analog measurement will have a
dedicated calibrated error correction factor.
POWER MOSFET / LED DRIVER AND MONITOR
it may be used to drive small loads like LEDs or MOSFET
gates. It was specifically designed to power up in the Normal
mode with the inputs tri-state. This was done to ensure the
LEDs or MOSFETs connected to the 33993 power up in the
off-state. The Switch Programmable (SP0 – SP7) inputs have
a source-and-sink capability, providing effective MOSFET
gate control. To complete the circuit, a pull-down resistor
should be used to keep the gate from floating during the
Sleep modes.
where the SG0 input is used to monitor the drain-to-source
voltage of the external MOSFET. The 1.5 kΩ resistor is used
to set the drain-to-source trip voltage. With the 2.0 mA
current source enabled, an interrupt will be generated when
the drain-to-source voltage is approximately 1.0 V.
The ADC value of 213 counts is the value with 0% error
This A / D conversion is 3% low in value. The error
An error correction factor may then be stored in E
Because of the flexible programming of the 33993 device,
ADC =
ADC =
Figure
ADC = 207 counts x 1.03
ADC =
ADC = 213 counts
2.05 mA x 2.39 kΩ
ADC = 213 counts
14, page 22, shows an application
1.99 mA x 2.0 kΩ
2.0 mA x 2.39 kΩ
ADC = 207 counts
2.0 mA x 2.0 kΩ
I1 x R1
I2 x R2
x 225
TYPICAL APPLICATIONS
x 225
x 225
INTRODUCTION
2
33993
21