MLX902xx Name of Sensor Rev Y.X 22/Aug/98 Page 1
MLX90711
Position/movement Sensing Auto-Shutoff
MLX90711 Position/movement Sensing Auto-Shutoff Page 1 Rev 1.0 15/Sep/00
Features and Benefits
Safety Auto shut off based on movement or position sensing.
Low cost – minimal external components.
Very reliable patented capacitive sensor,
insensitive to erosion and dust.
On chip calibrated timer.
Pdip8 or sop8 package.
Drives different relay types, including low cost
12V relays and most custom made relays.
Auto shut off status is indicated via a led.
Several timing options available.
Applications
Irons, fryers, ...
Ordering Information
Part No. Temperature Suffix Package version Temperature Range
MLX90711 S A -x 0C to 105C
MLX90711 S L -x 0C to 105C
The customer specific version code (defining the options) is indicated with 1 character at the end of the ordering
number.
Description
The Automatic Shut-Off is a safety system which
turns off the electrical power of a load based either
on a movement detection or a position detection.
This detection will be taken into account after a well
defined time delay. A typical application is the safety
feature in irons which will switch off the heating
element when the iron is left immobile for a well
defined period, which can be dependant on the
position. The state of the Auto Shut-Off can be
indicated with an led.
Functional Diagram
Regulator & bias
Sequencer
Osc
Relay
Logic
ADC
LED
VSS
VDD1
RD
LEDP
SUM
CA1
CA0
90711
MLX90711
Position/movement Sensing Auto-Shutoff
MLX90711 Position/movement Sensing Auto-Shutoff Page 2 Rev 1.0 15/Sep/00
Introduction
The Automatic Shut-Off is a safety system which
turns off the electrical power of a load based either
on a movement detection or a position detection.
This detection will be taken into account after a well
defined time delay. A typical application is the safety
feature in irons which will switch off the heating
element:
if the iron is connected to the mains and left
immobile in the ironing position for a time larger than
TH;
OR
if the iron is connected to the mains and left
vertically up on heel rest for a time larger than TV.
OR
if the iron is connected to the mains and left
vertically down on heel rest for a time larger than TD.
The heating of the iron is turned on again
immediately after detecting a different position (or
detecting a movement).
Sensing Principal
Melexis developed a new concept of Auto Shut-Off in
which the position or movement detection is realized
with a patented capacitive detection. This sensor
uses the movement of a ball, but the detection is
capacitive, and therefore, the system does not need
a conductive contact. Consequently, the system is
insensitive to erosion and dust.
The sensitivity of the asic is very high, and a ball with
a diameter as small as 3 mm can be used.
This detection system described in the following
section is protected by a patent (Patent European
application Nr. EP0589092; US application Nr.
US5627316).
General Description
The detection is done based on the ratio of two
variable capacitors. These capacitors can be the
parasitic capacitances of a small conductive ball
placed on a cavity in the pcb. As the pcb is rotated in
its lenghty direction, the ball is running forwards and
backwards on the pcb. Copper tracks placed on the
PCB at the edges of the hole will be used as the
terminals of capacitors. We can define two
capacitors made up of 2 copper tracks with a
(conductive) ball in between. If the ball rolls just
between 2 copper tracks, the distance between the
copper tracks and the ball will decrease, thus
increasing their capacitance. The circuitry on chip
performs a measurement of the difference between
these 2 caps. It controls the sense terminals (CA0,
CA1, SUM), processes their data and drives 2
outputs: RD (to drive a relay) and LEDP (to drive an
led). The information from the detection system
results in a momentary down, up or horizontal
position. This information can be used to generate a
position detection or can be interpreted as a
movement detection.
When used as a position sensor, the output of the
sensor consists of 3 digital signals, indicating the
position of the sensor: the ball is in the middle
(horizontal), is at the front side (down) or is at the
end (up). The position of the ball is sensed every
15.6 msec. For this the analog output voltage of the
sensor circuit is sent to 3 comparators with
hysteresis. If the result is equal for 3 consecutive
samples, the corresponding digital signal (DOWN,
UP or HOR) becomes valid. This signal is used to
evaluate the Auto Shut-Off function. The Auto ShutOff is active only when UP remains high during a
time period larger than TV or when HOR remains
high during a time period larger than TH or when
DOWN remains high during a time larger than TD.
The signals UP, HOR and DOWN are debounced.
When the Auto Shut-Off is active the relay driver is
activated. Using a NC (normally closed) type relay,
this can switch off the power of the heating element.
When the module is moved, the ball can roll forwards
and backwards in such a way that the states UP,
HOR and DOWN never remain stable for a time
more than TV, TH and TD respectively and the relay
output is not activated.
As long as the vertical inclination is enough to keep
the ball in the "vertical" area, the state UP remains
active.
When used as a movement sensor the output of the
sensor has only one signal which indicates that the
position of the ball has changed. If this signal is
inactive for the predefined time period TASO, the
chip enters the Auto Shut-Off state. The position of
the ball is sensed every 15.6 msec. When the Auto
Shut-Off is active the relay driver is activated. Using
a NC type relay, this can switch off the power of the
heating element.
When the module is moved, the ball can roll forwards
and backwards and due to this the chip continuously
detects a change of state of the sensor.
Power On Reset
In the chip there is a block "Power On Reset" (POR),
which tracks the level of the power supply voltage
Vdd1 and defines the state of the chip.
If Vdd1 is less than the high POR level (PORHI) after
initial plugging into the mains, the chip is in the "reset
state". When Vdd1 becomes higher than the PORHI
level, the operation of the chip starts: start up
sequence, heating up and then the chip enters in
"normal operation mode".
If Vdd1 becomes less than the low POR level
(PORLO), (PORLO=PORHI-HYS), for more than
7.8msec the chip enters the "reset state".
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MLX90711
Position/movement Sensing Auto-Shutoff
MLX90711 Position/movement Sensing Auto-Shutoff Page 3 Rev 1.0 15/Sep/00
Power down timing
After disconnecting the mains , the chip will reset:
- within typical 0.25sec when the coil is not activated
(iron is heating)
- within typical 2.5sec when the coil is activated (iron
is in ASO)
Relay and led driver options
The relay is driven by a pulsed signal instead of a
continuous signal. Consequently, the power
consumption is reduced.
The relay driver performs this feature. There are
four duty cycles available: 14.4%,16%, 28% and
31%. During 7.8 ms after the switching time , the
duty cycle is increased. This will give an increased
energy to the relay for a short time at the moment the
relay coil must change the state of the contact. The
switching time starts by applying the control voltage
on the coil of the relay. The values of the duty cycles
for the first 7.8 ms are in the table in brackets. The
switching frequency of relay and led are the same
and are typically 20.48KHz.
The type of relay should be normally closed (NC). A
NC relay is opened by applying the control voltage
on its coil and in this case the module is in Auto
Shut-Off mode.
Applications Example
PCB
Regulator & bias
Sequencer
Osc
Relay
Logic
ADC
LED
VSS
VDD1
RD
LEDP
SUM
CA1
CA0
90711
down
horizontal
up
copper track
cavity
ball
ball position
SRD1 SRD2 Relay DC Led DC
0 0 14.4%(28%) 14.4%(28%)
0 1 28%(43%) 28%(43%)
1 0 16%(31%) 16%(31%)
1 1 31%(48%) 31%(48%)
VSS
LEDP
VDD
1
90711
RD
Relay - Led output configuration
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Position/movement Sensing Auto-Shutoff
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Movement Auto Shut-Off time
When used as a movement Auto Shut-Off module,
several timing options are available. All timings are
derived from the on chip oscillator and have thus the
same tolerance.
If the module is left immobile for a time longer than
TASO the auto shut-off function becomes active.
There is also an additional time period TADI. This
time is valid only in the vertical state and determines
the time between shut-off and the start of the led
blinking.
Position Auto Shut-Off
When used as a position Auto Shut-Off module,
several timing options are available. All timings are
derived from the on chip oscillator and have thus the
same tolerance.
Three different time delays can be defined: the
horizontal shut-off (TH), the vertical shut-off (TV) and
the down shut-off (TD).
Start up sequence
When connecting the asic to the AC line the asic first
passes through a startup sequence. The duration of
this sequence is 1.25 or 3.75 seconds depending on
the duration of phase 1. After the start up test the
normal function of the chip begins. This sequence
involves the following phases :
PHASE 0: The duration is a time period
“TS”, which incorporates the Power On Reset time
period. This time ‘TS” is typically 0.2 sec.
PHASE 1: The duration is 0.5 second or 3
seconds. This can be defined by the mask option
SPH1. During this phase the iron heats. The ASO
function is not active. The LED is off. The relay is
NC and the control voltage is not applied to its coil
during this phase.
PHASE 2: The duration is 0.75 second. The
ASO function is active. The iron is not heating. The
control voltage is applied to the coil of the relay
during this phase. The LED indicates that the ASO
function is active. Some additional information is
sent out by the led driver during this phase. This
information involves three frequency codes.
- the first code is the highest digital clock
(20.48kHz). The duration is 250ms.
- the second code is the inform ation of the
position sensor. The frequency depends on the
position of the module:
- the third code is the information of the
metal mask where the customer specific options are
defined. It is coded using one of five frequencies
(20kHz, 10kHz, 5kHz, 2.5kHz, 1.25kHz).
EMC
Thanks to a special algorithm the sensor is made
very insensitive to noise and AC line coupling.
ESD Precautions
Electronic semiconductor products are sensitive to
Electro Static Discharge (ESD).
Always observe Electro Static Discharge control
procedures whenever handling semiconductor
products.
position LED frequency (KHz)
UP 1.28
Between UP and HOR 2.56
HOR 5.12
Between HOR and DO 10.24
DO 20.48
version TD TH TV
V1 30” 30” 4’
V2 30” 30” infinity
V3 30” 5” 8’
V4 30” 30” 8’
position sensor options
version TASO TADI
V1 30 sec 0
V2 30 sec 4 min
V3 4 min 0
V4 1 min 0
V5 10 min 0
V6 2 min 0
V7 8 min 0
V8 30 sec 8 min
Movement sensor options
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Position/movement Sensing Auto-Shutoff
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Depending on the position of the sensor the voltage
at the TEST1 output will change.
The pin TEST1 is also used as digital I/O during the
asic production test.
Options
Following is a summary of the options that can be
changed with the metal mask:
Pinout
Standard package is 8-pin dual inline package or 8pin sop package.
Side Position Shut-Off
The design of the cavity in the pcb, on which the ball
of the sensor is moving, as well as the design of the
protective cover important aspects. When designed
properly the function of the Auto Shut-Off module
can also be defined when the module is rotated
around the axis perpendicular to the normal axis,
even when the ball tends to fall off of the pcb. In the
application of an iron this can be useful for defining
the functionality when the iron is put at his side.
Heating Up feature
If the heating up feature is present, it inhibits the
Auto Shut-Off function for 1 minute and 30 seconds
after the start up sequence regardless of the position
or the movement of the iron. If the iron is left
immobile the asic will activate the relay output after 1
min and 30 sec added to the time TH (or TV or TD
depending on the position).
If the heating up feature not present, the Auto ShutOff function is available as soon as the iron is
plugged: so the relay contacts will switch off after a
time TH if it is left in the ironing position without
movement , or after time TV if it is left vertically up,
or after time TD if it is left vertically down.
Sensor test mode
To measure the performance of the sensor in the
module, a sensor test mode is implemented. This
test mode is activated via the test pin TEST1, which
is normally left open. When connecting the pin
TEST1 to an external 12V supply (with respect to the
asic ground VSS) via a resistor of 220 Kohm the test
mode is activated and the output of the on chip
integrator is now available at the pin TEST1.
DIP8 SOP8 Name Type Description
1 2 CA1 Output Sensor output CA1
2 3 VSS Supply Ground
3 4 SUM Input Sensor input
4 5 TEST1 Output Test output
5 6 VDD1 Supply Power supply
6 7 LEDP Output Led driver
7 8 RD Output Relay driver
8 1 CA0 Output Sensor output CA0
PCB top view
normal rotation axis
side position
rotation axis
parameter value option
POSMOV 0 Position sensing
1 Movement sensing
V1—V8
SPH1 0 Phase 1 of startup se-
quence is 0.5 sec.
1 Phase 1 of startup se-
quence is 3 sec.
HEATUPM 0 No heatup feature
1 Heatup feature present
SRD1 + SRD2 Select relay and led driver options
Select timing options
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Position/movement Sensing Auto-Shutoff
MLX90711 Position/movement Sensing Auto-Shutoff Page 6 Rev 1.0 15/Sep/00
MLX90711 Electrical Specifications
DC Operating Parameters TA = 0oC to 105oC
Parameter Symbol Test Conditions Min Typ Max Units
Power supply range VDD1 60 70 V
Zener protection IVZ1 VDD1 = 68V 10 mA
IVZ2 VDD1 = 60V 1 mA
Current consumption Idd1 VDD1 = 50V 0.8 mA
MLX90711 Internal clock
Parameter Symbol Test Conditions Min Typ Max Units
Clock period Tcl 48.9 usec
Initial deviation Erri -8 8 %
Deviation over temperature Errt -4 4 %
Deviation over Vdd1 Errv -3 3 %
MLX90711 Auto shut-off timing tolerance
Parameter Symbol Test Conditions Min Typ Max Units
DO auto shut-off time td -15 15 %
HOR auto shut-off time th -15 15 %
VERT auto shut-off time tv
-15 15 %
MLX90711 Relay driver
Parameter Symbol Test Conditions Min Typ Max Units
Leakage current Irdlk Vrd = Vdd1 10 uA
On resistance Rrdon At 30mA 90 ohm
Parameter Symbol Test Conditions Min Typ Max Units
Leakage current Iledlk Vledp = Vdd1—5V 10 uA
On resistance Rledon At 30mA 50 ohm
MLX90711 Led driver
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Position/movement Sensing Auto-Shutoff
MLX90711 Position/movement Sensing Auto-Shutoff Page 7 Rev 1.0 15/Sep/00
MLX90711 Power on reset
Parameter Symbol Test Conditions Min Typ Max Units
Upper level PORHI 30 40 V
hysteresis PORHYS 5 10 V
MLX90711
Position/movement Sensing Auto-Shutoff
MLX90711 Position/movement Sensing Auto-Shutoff Page 8 Rev 1.0 15/Sep/00
Application Example
PCB
VSS
VDD1
RD
LEDP
SUM
CA1
CA0
90711
L
Load
N
R1
D1
LED1
D2
C1
REL1
The above drawing shows the electrical schematic of a typical application.
The asic is directly connected to the AC line via a resistor R1 and diode D1, thus supplying the asic during
only the positive cycle of the AC line voltage. A capacitor C1 is therefore added between VDD1 and VSS to
smooth the asic supply voltage. The asic will limit the voltage at VDD1 at approximately 60V. A 12V relay
REL1 can be used to load the pin RD. The relay is driven with a well defined duty cycle to ensure that the relay is driven with the right energy. The relay driver needs a flyback diode D2. A led LED1 can be added to
indicate the state of the asic. If no led is used, it must be replaced by a short circuit.
Special care must be paid to the layout of the sensor on the pcb and to the connections between sensor and
asic. The asic is designed to detect very small variations in capacitance in the sensor. Therefore parasitic capacitances must be kept as small as possible, and injection of noise must be avoided.
MLX902xx Name of Sensor Rev Y.X 22/Aug/98 Page 9
MLX90711
Position/movement Sensing Auto-Shutoff
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signal at TEST1 output
detecting UP state
signal at TEST1 output
detecting DOWN state
sensor output measurement
PCB
VSS
VDD1
RD
LEDP
SUM
CA1
CA0
90711
L
Load
N
TEST1
220Kohm
12 V
MLX90711
Position/movement Sensing Auto-Shutoff
MLX90711 Position/movement Sensing Auto-Shutoff Page 10 Rev 1.0 15/Sep/00
“A” Package Dimensions
9.02
10.16
Min
Max
18.67
19.68
18.67
19.68
22.35
23.67
24.89
26.92
31.24
32.51
0.20
0.38
2.54
BSC
1.1
5
1.7
7
0.35
0.55
0.39
Min
Dimension 8 Leads 16 Leads 18 Leads 20 Leads14 Leads 24 Leads
A
6.10
7.11
5.33
MAX
2.93
4.06
7.62
BSC
10.92
Max
A
Notes:
1-All measurements in mm
2-Body dimensions do not include mold
flash or protrusion - not to exceed
0.15mm
Disclaimer
Melexis reserves the right to periodically make modifications to product specifications. The information
included herein is believed to be accurate and reliable. However, Melexis assumes no responsibility
for its use; nor for any infringements of patents or
other rights of third parties which may result from its
use.
MLX902xx Name of Sensor Rev Y.X 22/Aug/98 Page 11
MLX90711
Position/movement Sensing Auto-Shutoff
MLX90711 Position/movement Sensing Auto-Shutoff Page 11 Rev 1.0 15/Sep/00
“L” Package Dimensions
For the latest version of this document,
Go to our website at:
www.melexis.com
Or for additional information
contact Melexis Direct:
USA
Melexis Inc.
41 Locke Road, Concord, NH 03301
Phone: +1 603 223 2362 Fax: +1 603 223 9614
E-mail: sales_usa@melexis.com
United Kingdom
Silicon Concepts
PCB Lynchborough Road, Hampshire GU30 7SB, United Kingdom
Phone: +44 1428 751 617 Fax: +44 1428 751 603
E-mail: sales_uk@melexis.com
Germany
Am Seestern 8, 40547 Düsseldorf, Germany
Phone: +49 211 5360212 Fax: +49 211 5360250
E-mail: sales_de@melexis.com
France
Melexis France
Tour Arago, 5 rue Bellini, 92806 Puteaux-La-Défense, France.
Phone: +33 1 47 78 11 34 Fax: +33 1 47 78 06 35
E-mail: sales_france@melexis.com
Italy
Dimacred IRL
Via Papa Giovanni XXIII no. 25, 20046 Biassono, Italy
Phone: +39 039 249 4856 Fax: +39 039 491773
E-mail: sales_italy@melexis.com
Japan
Satori Electric Co., LTD
1-14-10 Shiba, Minato-Ku, Tokyo, Japan
Phone: +81 3 3452 7171 Fax: +81 3 3769 2197
E-mail: sales_japan@melexis.com
Taiwan
Beechwood Int’l Taiwan Co.
Room 8, 17F, No. 189, Taipei, Taiwan
Phone: +886 2 2739 3322 Fax: +886 2 2739 3090
E-mail: sales_taiwan@melexis.com
0.40
1.27
0o to 8
o
2.35
2.65
0.010 min.
0.33
0.51
A
Dimension 8 Leads 14 Leads
A
4.80
5.00
Min
Max
8.55
8.75
16 Leads
9.80
10.00
3.80
4.00
5.80
6.20
1.27
Notes:
1-All nominal measurements in millimeters
2-Body dimensions do not include mold flash or
protrusion - not to exceed 0.15mm
MLX90711
Position/movement Sensing Auto-Shutoff
MLX90711 Position/movement Sensing Auto-Shutoff Page 12 Rev 1.0 15/Sep/00
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