MLX90711

Position/movement Sensing Auto-Shutoff

3901090711

Page 1 of 15

Data Sheet

Rev. 003

Dec/02

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.

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 Code

Option Code*

MLX90711

C ( 0°C to 70°C )

AA (PDIP8)

BB / BC

MLX90711

C ( 0°C to 70°C )

DC (SOIC8)

BB / BC

* See Option Code Table for details

1. Functional Diagram

Regulator & bias

Sequencer

Osc

Relay

Logic

ADC

LED

VSS

VDD1

LEDP

SUM

CA1

CA0

2. Description

The Automatic Shut-Off is a safety system, which
turns off the electrical power of a load based either
on movement detection or 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 a led.

MLX90711

Position/movement Sensing Auto-Shutoff

3901090711 Page

2 of 15 Data Sheet

Rev. 003

Dec/02

TABLE OF CONTENTS

FEATURES AND BENEFITS........................................................................................................................1

APPLICATIONS ............................................................................................................................................1

ORDERING INFORMATION .........................................................................................................................1

FUNCTIONAL DIAGRAM ...................................................................................................................

...1

DESCRIPTION ....................................................................................................................................

...1

ABSOLUTE MAXIMUM RATINGS........................................................................................................3

MLX90711 ELECTRICAL SPECIFICATIONS.......................................................................................3

MLX90711 SPECIFIC SPECIFICATIONS .............................................................................................3

GENERAL DESCRIPTION ....................................................................................................................5

PINOUT DESCRIPTION ........................................................................................................................8

APPLICATIONS INFORMATION ..........................................................................................................9

8.1.

PPLICATION EXAMPLE

.................................................................................................................................. 9

8.2.

ENSOR

UTPUT

EASUREMENT

................................................................................................................. 10

8.3.

PTION

ODE

ABLE

................................................................................................................................... 11

RELIABILITY INFORMATION.............................................................................................................12

10.

ESD PRECAUTIONS ...........................................................................................................................12

11.

PACKAGE INFORMATION .................................................................................................................13

12.

DISCLAIMER .......................................................................................................................................15

MLX90711

Position/movement Sensing Auto-Shutoff

3901090711

Page 3 of 15

Data Sheet

Rev. 003

Dec/02

3. Absolute Maximum Ratings

Supply Voltage, V

DD1

(overvoltage)

73V

Supply Voltage, V

DD1

(operating)

68V

Maximum chip temperature

125

ESD Sensitivity (AEC Q100 002)

2kV

Exceeding the absolute maximum ratings may cause permanent damage. Exposure to absolute
maximum-rated conditions for extended periods may affect device reliability.

4. MLX90711 Electrical Specifications

DC Operating Parameters T

= 0

C to 85

Parameter Symbol

Test

Conditions

Min

Typ

Max

Units

Power supply range

VDD1

= 5 mA

Current consumption

Idd1

VDD1 = 50V

0.1

0.6

3.1

5. MLX90711 Specific Specifications

Internal clock

Parameter Symbol

Test

Conditions

Min

Typ

Max

Units

Clock

period

Tcl

48.9

usec

Initial deviation

Erri

-8

Deviation over temperature

Errt

-4

Deviation over Vdd1

Errv

-3

Auto shut-off timing tolerance

Parameter Symbol

Test

Conditions

Min

Typ

Max

Units

DO auto shut-off time

-15

HOR auto shut-off time

-15

VERT auto shut-off time

-15

Driver Resistance

Parameter Symbol

Test

Conditions

Min

Typ

Max

Units

Relay Driver On resistance

Rrdon

At 30mA

ohm

Led Driver On resistance

Rledon

At 30mA

ohm

MLX90711

Position/movement Sensing Auto-Shutoff

3901090711

Page 5 of 15

Data Sheet

Rev. 003

Dec/02

6. General Description

Introduction

The Automatic Shut-Off is a safety system which
turns off the electrical power of a load based either
on movement detection or 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).

Detection system

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 lengthy 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 position detection or can be
interpreted as 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 Shut-Off 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,
called 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.

MLX90711

Position/movement Sensing Auto-Shutoff

3901090711

Page 6 of 15

Data Sheet

Rev. 003

Dec/02

PCB

Regulator & bias

Sequencer

Osc

Relay

Logic

ADC

LED

VSS

VDD1

LEDP

SUM

CA1

CA0

MLX90711

down

horizontal

copper track

cavity

ball

ball position

Position/Movement 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".

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.

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

VDD1

MLX90711

Relay - Led output configuration

The type of relay should be normally closed (NC).
A NC relay is opened by applying the control

MLX90711

Position/movement Sensing Auto-Shutoff

3901090711

Page 7 of 15

Data Sheet

Rev. 003

Dec/02

voltage on its coil and in this case the module is
in Auto Shut-Off mode.

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.

Movement sensor options

version TASO

TADI

V1 30

sec

30 sec

4 min

V3 4

min 0

V4 1

min 0

V5 10

min

V6 2

min 0

V7 8

min 0

30 sec

8 min

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 TD

V1 30" 30" 4'
V2 30" 30" infinity
V3 30" 5" 8'
V4 30" 30" 8'

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 information of the

position sensor. The frequency depends on the
position of the module. See table below.

- The third code is the information for 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).

*Phase2 is 0.5s for MLX90711 BC. No third code.

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

EMC

Thanks to a special algorithm the sensor is made
very insensitive to noise and AC line coupling.

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.

MLX90711

Position/movement Sensing Auto-Shutoff

3901090711

Page 8 of 15

Data Sheet

Rev. 003

Dec/02

PCB top view

normal rotation axis

side position

rotation axis

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
Shut-Off 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. 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 tests.

Options

Following is a summary of the options that can be
changed with the metal mask:

parameter value

option

POSMOV 0 Position

sensing

Movement

sensing

V1--V8

Select timing options

SPH1 0

Phase 1 of startup

sequence is 0.5 sec.

Phase 1 of startup

sequence is 3 sec.

HEATUPM

No heatup feature

Heatup feature present

SRD1 + SRD2

Select relay and led driver options

7. Pinout Description

PDIP8 SOIC8 Name

Type

Description

CA1

Output

Sensor output CA1

2 7 VSS

Supply Ground

3 8 SUM

Input

Sensor

input

4 1 TEST1 Output Test

output

5 2 VDD1 Supply Power

supply

6 3 LEDP

Output Led

driver

7 4 RD

Output Relay

driver

CA0

Output

Sensor output CA0

MLX90711

Position/movement Sensing Auto-Shutoff

3901090711

Page 9 of 15

Data Sheet

Rev. 003

Dec/02

8. Applications Information

8.1. Application example

Application Example

PCB

VSS

VDD1

LEDP

SUM

CA1

CA0

MLX90711

Load

LED1

REL1

The above drawing shows the electrical
schematic of a typical application with NC relay
type.
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 voltage at VDD1 is limited to
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.

MLX90711

Position/movement Sensing Auto-Shutoff

3901090711

Page 12 of 15

Data Sheet

Rev. 003

Dec/02

9. Reliability

Information

Melexis devices are classified and qualified regarding suitability for infrared, vapor phase and wave
soldering with usual (63/37 SnPb-) solder (melting point at 183degC).
The following test methods are applied:

IPC/JEDEC J-STD-020A (issue April 1999)
Moisture/Reflow Sensitivity Classification For Nonhermetic Solid State Surface Mount Devices
CECC00802 (issue 1994)
Standard Method For The Specification of Surface Mounting Components (SMDs) of Assessed Quality
MIL 883 Method 2003 / JEDEC-STD-22 Test Method B102
Solderability

For all soldering technologies deviating from above mentioned standard conditions (regarding peak
temperature, temperature gradient, temperature profile etc) additional classification and qualification tests
have to be agreed upon with Melexis.

The application of Wave Soldering for SMD's is allowed only after consulting Melexis regarding assurance
of adhesive strength between device and board

For more information on manufacturability/solderability see quality page at our website:

http://www.melexis.com/

10. ESD Precautions

Electronic semiconductor products are sensitive to Electro Static Discharge (ESD).
Always observe Electro Static Discharge control procedures whenever handling semiconductor products.

MLX90711

Position/movement Sensing Auto-Shutoff

3901090711

Page 15 of 15

Data Sheet

Rev. 003

Dec/02

12. Disclaimer

Devices sold by Melexis are covered by the warranty and patent indemnification provisions appearing in
its Term of Sale. Melexis makes no warranty, express, statutory, implied, or by description regarding the
information set forth herein or regarding the freedom of the described devices from patent infringement.
Melexis reserves the right to change specifications and prices at any time and without notice. Therefore,
prior to designing this product into a system, it is necessary to check with Melexis for current information.
This product is intended for use in normal commercial applications. Applications requiring extended
temperature range, unusual environmental requirements, or high reliability applications, such as military,
medical life-support or life-sustaining equipment are specifically not recommended without additional
processing by Melexis for each application.
The information furnished by Melexis is believed to be correct and accurate. However, Melexis shall not
be liable to recipient or any third party for any damages, including but not limited to personal injury,
property damage, loss of profits, loss of use, interrupt of business or indirect, special incidental or
consequential damages, of any kind, in connection with or arising out of the furnishing, performance or
use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow
out of Melexis' rendering of technical or other services.
© 2002 Melexis NV. All rights reserved.

For the latest version of this document,

go to our website at:

www.melexis.com

Or for additional information contact Melexis Direct:

Europe and Japan:

All other locations:

Phone: +32 13 67 04 95

Phone: +1 603 223 2362

E-mail: sales_europe@melexis.com

E-mail: sales_usa@melexis.com

QS9000, VDA6.1 and ISO14001 Certified

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