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MLX90711
Position/movement Sensing Auto-Shutoff
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.
Functional Diagram
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.
90711 CA0 Sequencer
VDD1
Regulator & bias CA1
Osc SUM
ADC
Relay RD
Logic VSS
LED LEDP
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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.
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
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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Applications Example
ball
copper track
PCB CA0
cavity
90711
VDD1
Sequencer Regulator & bias CA1 Osc SUM
down horizontal up ADC
Relay RD
Logic VSS
LED LEDP
ball position
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)
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.
Relay - Led output configuration
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
VDD 1
LEDP 90711 RD
SRD1 0 0 1 1
SRD2 0 1 0 1
Relay DC 14.4%(28%) 28%(43%) 16%(31%) 31%(48%)
Led DC 14.4%(28%) 28%(43%) 16%(31%) 31%(48%)
VSS
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.
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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. 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 information 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).
Movement sensor options version V1 V2 V3 V4 V5 V6 V7 V8 TASO 30 sec 30 sec 4 min 1 min 10 min 2 min 8 min 30 sec TADI 0 4 min 0 0 0 0 0 8 min
position UP Between UP and HOR HOR Between HOR and DO DO
LED frequency (KHz) 1.28 2.56 5.12 10.24 20.48
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).
position sensor options version V1 V2 V3 V4 TD 30" 30" 30" 30" TH 30" 30" 5" 30" TV 4' infinity 8' 8'
EMC
Thanks to a special algorithm the sensor is made very insensitive to noise and AC line coupling.
ESD Precautions 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 Electronic semiconductor products are sensitive to Electro Static Discharge (ESD). Always observe Electro Static Discharge control procedures whenever handling semiconductor products.
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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. 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
parameter POSMOV
value 0 1
option Position sensing Movement sensing
PCB top view
V1--V8 SPH1
Select timing options 0 1 Phase 1 of startup sequence is 0.5 sec. Phase 1 of startup sequence is 3 sec. No heatup feature Heatup feature present
side position rotation axis
HEATUPM
0 1
normal rotation axis
SRD1 + SRD2
Select relay and led driver options
changed with the metal mask:
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.
Pinout
Standard package is 8-pin dual inline package or 8pin sop package.
DIP8 1 2 3 4 5 6 7 8
SOP8 Name 2 3 4 5 6 7 8 1 CA1 VSS SUM TEST1 VDD1 LEDP RD CA0
Type Output Supply Input Output Supply Output Output Output
Description Sensor output CA1 Ground Sensor input Test output Power supply Led driver Relay driver Sensor output CA0
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.
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MLX90711 Electrical Specifications
DC Operating Parameters TA = 0oC to 105oC Parameter Symbol Test Conditions Power supply range Zener protection VDD1 IVZ1 IVZ2 Current consumption Idd1 VDD1 = 68V VDD1 = 60V VDD1 = 50V Min 60 10 1 0.8 Typ Max 70 Units V mA mA mA
MLX90711 Internal clock
Parameter Clock period Initial deviation Symbol Tcl Erri -8 -4 -3 Test Conditions Min Typ 48.9 8 4 3 Max Units usec % % %
Deviation over temperature Errt Deviation over Vdd1 Errv
MLX90711 Auto shut-off timing tolerance
Parameter DO auto shut-off time HOR auto shut-off time VERT auto shut-off time Symbol td th tv Test Conditions Min -15 -15 -15 Typ Max 15 15 15 Units % % %
MLX90711 Relay driver
Parameter Leakage current On resistance Symbol Irdlk Rrdon Test Conditions Vrd = Vdd1 At 30mA Min Typ Max 10 90 Units uA ohm
MLX90711 Led driver
Parameter Leakage current On resistance Symbol Iledlk Rledon Test Conditions Vledp = Vdd1--5V At 30mA Min Typ Max 10 50 Units uA ohm
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MLX90711 Power on reset
Parameter Upper level hysteresis Symbol PORHI PORHYS Test Conditions Min 30 5 Typ Max 40 10 Units V V
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Application Example
D1 R1 L
Load
PCB
90711 CA0 CA1
REL1 C1
VDD1 LEDP
LED1 D2
SUM VSS
RD
N
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.
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sensor output measurement
L
Load
PCB
90711 CA0 CA1 SUM RD TEST1 VSS
N 220Kohm 12 V
VDD1 LEDP
signal at TEST1 output detecting UP state
signal at TEST1 output detecting DOWN state
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"A" Package Dimensions
0.20 0.38
6.10 7.11
7.62 10.92 BSC Max
1.1 5 1.7 7
2.54 BSC A 5.33 MAX 2.93 0.39 4.06 Min 0.35 0.55
Notes: 1-All measurements in mm 2-Body dimensions do not include mold flash or protrusion - not to exceed 0.15mm
Dimension
8 Leads Min Max 9.02 10.16
14 Leads 18.67 19.68
16 Leads 18.67 19.68
18 Leads 22.35 23.67
20 Leads 24.89 26.92
24 Leads 31.24 32.51
A
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.
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"L" Package Dimensions
3.80 4.00
5.80 6.20 0.40 1.27
0.33 0.51
1.27 0o to 8o
Notes:
A
1-All nominal measurements in millimeters 2-Body dimensions do not include mold flash or protrusion - not to exceed 0.15mm
2.35 2.65
0.010 min.
Dimension
8 Leads Min Max 4.80 5.00
14 Leads 8.55 8.75
16 Leads 9.80 10.00
A
For the latest version of this document, Go to our website at:
France
Melexis France Tour Arago, 5 rue Bellini, 92806 Puteaux-La-Defense, France. Phone: +33 1 47 78 11 34 Fax: +33 1 47 78 06 35 E-mail: sales_france@melexis.com
www.melexis.com
Or for additional information contact Melexis Direct:
Italy USA
Melexis Inc. 41 Locke Road, Concord, NH 03301 Phone: +1 603 223 2362 E-mail: sales_usa@melexis.com Fax: +1 603 223 9614 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
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 Dusseldorf, Germany Phone: +49 211 5360212 Fax: +49 211 5360250 E-mail: sales_de@melexis.com
Taiwan
Beechwood Int'l Taiwan Co. Room 8, 17F, No. 189, Taipei, Taiwan Phone: +886 2 2739 3322 E-mail: sales_taiwan@melexis.com Fax: +886 2 2739 3090
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