Freescale Semiconductor
Technical Data
Document number: MC34940
Rev 4, 11/2006
Electric Field Imaging Device
The MC34940 is intended for cost-sensitive applications where non-contact
sensing of objects is desired. When connected to external electrodes, an
electric field is created. The MC34940 detects objects in this electric field. The
IC generates a low-frequency sine wave, which 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 MC34940 also
contains support circuits for a microcontroller unit (MCU) to allow the
construction of a two-chip E-field system.
Features
•
•
•
•
•
•
Supports up to 7 Electrodes
Shield Driver for Driving Remote Electrodes Through Coaxial
High-Purity Sine Wave Generator Tunable with External Resistor
Response Time Tunable with External Capacitor
Can support up to 28 touch pad sensors
Pb-Free and RoHS compliant
MC34940
ELECTRONIC FIELD
IMAGING DEVICE
Typical Applications
•
•
•
•
•
•
•
•
•
•
•
•
•
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
PC Peripherals
Patient Monitoring
Point of Sale Terminals
Size Detection
Liquid Level Sensing
ORDERING INFORMATION
Device Name
MC34940EG/R2
Temperature Range
0 to 90°C
Drawing
CASE 751E-04
Package
SOICW-24
EG SUFFIX (Pb-FREE)
24-TERMINAL SOICW
CASE 751E-04
DGND
N/C
SHIELDEN
C
B
A
LEVEL
LPCAP
ROSC
VDDCAP
VPWR
VCCCAP
N/C
E7
E6
E5
E4
E3
E2
E1
TEST
GND
SHIELD
AGND
Pin Connections
© Freescale Semiconductor, Inc., 2006. All rights reserved.
A,B,C
3
CONTROL
LOGIC
2.8 kΩ
E1-E7
2.8 kΩ
MUX
OUT
OSC
22 kΩ (Nominal)
ROSC
SHIELDEN
150
Ω
700
Ω
MUX
IN
SHIELD
700
Ω
RECT
LPCAP
VCCCAP
VDDCAP
V
CC
REG
V
DD
REG
LPF
GAIN AND
OFFSET
LEVEL
VPWR
AGND
GND
Figure 1. Simplified Functional Block Diagram
MC34940
2
Sensors
Freescale Semiconductor
Table 1. Maximum Ratings
All voltages are with respect to ground unless otherwise noted. Exceeding these ratings may cause a malfunction or permanent
damage to the device.
Rating
ELECTRICAL RATINGS
Peak V
PWR
Voltage
Double Battery
1 Minute Maximum T
A
= 30°C
ESD Voltage
Human Body Model (C
ZAP
= 100 pF, R
ZAP
= 1500
Ω)
Machine Model (C
ZAP
= 200 pF, R
ZAP
= 0
Ω)
Charge Device Model (CDM), Robotic (C
ZAP
= 4.0 pF)
THERMAL RATINGS
Storage Temperature
Operating Ambient Temperature
Operating Junction Temperature
Thermal Resistance
Junction-to-Ambient
(1)
Junction-to-Case
(2)
Junction-to-Board
(3)
Soldering Temperature
(4)
Notes
1.
Junction temperature is a function of on-chip power dissipation, package thermal resistance, mounting site (board) temperature,
ambient temperature, air flow, power dissipation of other components on the board, and board thermal resistance. In accordance with
SEMI G38-87 and JEDEC JESD51-2 with the single layer board horizontal.
Indicates the average thermal resistance between the die and the case top surface as measured by the cold plate method
(MILSPEC 883 Method 1012.1) with the cold plate temperature used for the case temperature.
Thermal resistance between the die and the printed circuit board per JEDEC JESD51-8. Board temperature is measured on the top
surface of the board near the package.
Terminal soldering temperature limit is for 10 seconds maximum duration. The device is not designed for immersion soldering.
Exceeding these limits may cause malfunction or permanent damage to the device.
T
STG
T
A
T
J
R
θ
JA
R
θ
JC
R
θ
JB
T
SOLDER
-55 to 150
-0 to 90
-0 to 150
41
0.2
3.0
260
°C
°C
°C
°C
°C/W
V
PWRPK
V
DBLBAT
V
ESD
40
26.5
V
±2000
±200
±1200
V
V
Symbol
Value
Unit
2.
3.
4.
MC34940
Sensors
Freescale Semiconductor
3
Table 2. Static Electrical Characteristics
Characteristics noted under conditions 5.5 V
≤
V
SUP
≤
18 V, 0°C
≤
T
A
≤
90°C, GND = 0 V unless otherwise noted. Typical
values noted reflect the approximate parameter means at T
A
= 25°C under nominal conditions unless otherwise noted.
Characteristic
SUPPLY (V
PWR
)
Supply Voltage
I
DD
(V
PWR
= 14 V)
(Quiescent supply current measured over temperature. Assumes
that no external devices connected to internal voltage regulators)
ELECTRODE SIGNALS (E1–E7)
Total Variance Between Electrode Measurements
(5)
All C
LOAD
= 15 pF
Electrode Maximum Harmonic Level Below Fundamental
(5)
5.0 pF
≤
C
LOAD
≤
150 pF
Electrode Transmit Output Range
5.0 pF
≤
C
LOAD
≤
150 pF
Receive Input Voltage Range
Grounding Switch on Voltage
(6)
I
SW
= 1.0 mA
LOGIC I/O (C, B, A)
CMOS Logic Input Low Threshold
Logic Input High Threshold
Voltage Hysteresis
Input Current
V
IN
= V
CC
V
IN
= 0 V
SIGNAL DETECTOR (LPCAP)
Detector Output Resistance
LPCAP to LEVEL Gain
LPCAP to LEVEL Offset
DET
RO
A
REC
V
RECOFF
–
3.6
-3.3
50
4.0
-3.0
–
4.4
-2.7
kΩ
A
V
V
V
THL
V
THH
V
HYS
I
IN
0.3
–
–
10
-5.0
–
–
0.06
–
–
–
0.7
–
50
5.0
V
CC
V
CC
V
CC
µA
ELV
VAR
EL
HARM
EL
TXV
RX
V
SW
VON
%
–
–
1.0
0
–
–
-20
–
–
–
3.0
dB
–
V
8.0
9.0
5.0
V
V
V
PWR
I
DD
V
9.0
6.0
12
7.0
18
mA
8.0
Symbol
Min
Typ
Max
Unit
Notes
5. Verified by design and characterization. Not tested in production.
6. Current into grounded terminal under test = 1.0 mA.
MC34940
4
Sensors
Freescale Semiconductor
Table 3. Dynamic Electrical Characteristics
Characteristics noted under conditions 5.5 V
≤
V
SUP
≤
18 V, 0°C
≤
T
A
≤
90°C, GND = 0 V unless otherwise noted. Typical
values noted reflect the approximate parameter means at T
A
= 25°C under nominal conditions unless otherwise noted.
Characteristic
OSC (ROSC)
OSC Frequency Stability
OSC Center Frequency
ROSC = 39 kΩ
ROSC = 20 kΩ
ROSC = 82 kΩ
Harmonic Content
2nd through 4th Harmonic Level
5th and Higher
SHIELD DRIVER (SHIELD)
Shield Driver Maximum Harmonic level below Fundamental
10 pF
≤
C
LOAD
≤
500 pF
Shield Driver Gain Bandwidth Product
Measured at 120 kHz
SD
HARM
SD
GBW
dB
–
–
-20
4.5
–
MHz
–
f
STAB
f
OSC
–
–
–
–
–
–
–
120
240
60
–
–
10
–
–
–
dB
-20
-60
%
kHz
Symbol
Min
Typ
Max
Unit
OSCH
ARM
MC34940
Sensors
Freescale Semiconductor
5
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