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MC33794EK

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18
Document Number: MC33794
Rev 9, 11/2006
Freescale Semiconductor
Technical Data
© Freescale Semiconductor, Inc., 2006. All rights reserved.
Electric Field Imaging Device
The MC33794 is intended for applications where noncontact sensing of
objects is desired. When connected to external electrodes, an electric field is
created.,The MC33794 is intended for use in detecting objects in this electric
field. The IC generates a low-frequency sine wave. The frequency is adjustable
by using an external resistor and is optimized for 120 kHz. The sine wave has
very low harmonic content to reduce harmonic interference.
The MC33794 also contains support circuits for a microcontroller unit (MCU)
to allow the construction of a two-chip E-field system.
Features
• Supports up to 9 Electrodes and 2 References or Electrodes
• Shield Driver for Driving Remote Electrodes Through Coaxial Cables
• +5.0 V Regulator to Power External Circuit
• ISO-9141 Physical Layer Interface
• Lamp Driver Output
• Watchdog and Power-ON Reset Timer
• Critical Internal Nodes Scaled and Selectable for Measurement
• High-Purity Sine Wave Generator Tunable with External Resistor
Typical Applications
• Occupant Detection Systems
• Appliance Control Panels and Touch Sensors
• Linear and Rotational Sliders
• Spill Over Flow Sensing Measurement
• Refrigeration Frost Sensing
• Industrial Control and Safety Systems Security
• Proximity Detection for Wake-Up Features
• Touch Screens
• Garage Door Safety Sensing
• Liquid Level Sensing
ORDERING INFORMATION
Device Name Temperature Range (T
A
)
Package
Drawing
Package
MC33794EK/R2 -40°C to 85°C 1390-02 54 SOICW-EP
ELECTRIC FIELD
IMAGING DEVICE
MC33794
EK SUFFIX
54-LEAD SOICW-EP
CASE 1390-02
Sensors
2 Freescale Semiconductor
MC33794
INTERNAL BLOCK DIAGRAM
Figure 1. Simplified Functional Block Diagram
CONTROL
LOGIC
MUX
OUT
OSC
MUX
IN
RECT
LPF
GAIN AND
OFFSET
ATTN
LAMP CKT
ISO-9141
POR/
WD
V
CC
REG
V
DD
REG
CLK
R_OSC
SHIELD_EN
SHIELD
LP_CAP
LEVEL
SIGNAL
LAMP_SENSE
LAMP_MON
LAMP_OUT
ISO_IN
ISO_OUT
LAMP_CTRL
LAMP_GND
V
DD
_
MON
PWR_MON
GND and HEAT SINK
AGND
V
PWR
WD_IN
RST
V
CC
V
DD
E1–E9
REF_A*, REF_B*
TEST
A,B,C,D
4
150
Ω
39 kΩ
10 nF
22 k
Ω (Nominal)
ISO-9141
2.8 kΩ
700 Ω*
2.8 kΩ
* REF_A and REF_B are
not switched to ground
when not selected.
300 Ω
700 Ω*
(Note: All Resistor Values are Nominal)
Sensors
Freescale Semiconductor 3
MC33794
SOICW-EP TERMINAL CONNECTIONS
Figure 2. SOICW-EP Terminal Connections
Table 1. SOICW-EP TERMINAL FUNCTION DESCRIPTION
Terminal
Terminal
Name
Formal Name Definition
1 RST Reset
This output is intended to generate the reset function of a typical MCU. It has a
delay for Power-ON Reset, level detectors to force a reset when V
CC
REG is
out-of-range high or low, and a watchdog timer that will force a reset if WD_IN
is not asserted at regular intervals. Timing is derived from the oscillator and will
change with changes in the resistor attached to R_OSC.
2 WD_IN Watchdog In
This terminal must be asserted and deserted at regular interval in order to
prevent
RST from being asserted. By having the MCU program perform this
operation more often the allowed time, a check that the MCU is running and
executing its program is assured. If this doesn’t occur, the MCU will be reset. If
the watchdog function is not desired, this terminal may be connected to CLK to
prevent a reset from being issued.
3, 5, 7,
20–23, 31,
33, 34,
48–50, 52
NC No connect
These terminals may be used at some future date and should be left open.
4 LAMP_GND Lamp Ground
This is the ground for the current from the lamp. The current into LAMP_OUT
flows out through this terminal.
6 LAMP_OUT Lamp Driver
This is an active low output capable of sinking current of a typical indicator lamp.
One end of the lamp should be connected to a positive supply (for example,
battery voltage) and the other side to this terminal. The current is limited to
prevent damage to the IC in the case of a short or surge during lamp turn-on or
burn-out.
LAMP_OUT
1
PWR_MON
LP_CAP
R_OSC
NC
NC
NC
NC
CLK
V
DD
_
MON
V
DD
V
PWR
LEVEL
11
12
13
14
15
16
17
18
19
20
9
10
21
22
23
24
25
26
27
6
7
8
4
5
SHIELD_EN
D
C
B
A
SIGNAL
NC
LAMP_SENSE
LAMP_MON
NC
LAMP_GND
NC
2
3
54
44
43
42
41
40
39
38
37
36
35
46
45
34
33
32
31
30
29
28
49
48
47
51
50
53
52
RST
WD_IN
NC
E3
E2
E1
TEST
NC
NC
GND
NC
SHIELD
AGND
V
CC
E4
REF_A
E9
E8
E7
E6
E5
NC
ISO_OUT
REF_B
NC
ISO_IN
NC
LAMP_CTRL
ISO-9414
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18

MC33794EK

Mfr. #:
Buy MC33794EK
Manufacturer:
NXP / Freescale
Description:
Proximity Sensors ODS 54LD
Lifecycle:
New from this manufacturer.
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