LAERDAL SUCTION UNIT (LSU) Technical Service Manual and Block Diagrams Rev E

PRO-P16-0001 Rev E

Table of Contents TABLE OF CONTENTS ... 2 1

GENERAL ... 4

2

TECHNICAL SPECIFICATION... 5 2.1 OVERVIEW ... 5 2.1.1 Power Board ... 5 2.1.2 MMI Board ... 5 2.1.3 Battery Board ... 5 2.1.4 Main Rotary Switch... 5 2.1.5 Front Panel ... 6 2.1.6 Block Diagram... 6 2.2 POWER SUPPLY ... 7 2.2.1 Battery ... 7 2.2.2 Environmental conditions ... 7 2.2.3 Battery charging... 8 2.2.4 AC Mains ... 8 2.2.5 According to IEC 60601-1 ... 8 2.2.6 DC Mains ... 9 2.2.7 Indicators ... 9 2.2.7.1 2.2.7.2 2.2.7.3 2.2.7.4 2.2.7.5 2.2.7.6

General ... 9 Operation ...10 External Power...10 Error...10 Battery Capacity and Charging ...10 Vacuum Indicators: ...10

2.3 VACUUM... 11 2.3.1 Vacuum sensor ... 11 2.3.2 Vacuum Valve ... 11 2.4 FLOW ... 12 2.5 NOISE ... 12 2.6 SIZE ... 12 2.7 WEIGHT ... 12 2.8 CLASSIFICATION ... 12 2.8.1 Various classifications of LSU ... 12 2.8.2 Other approvals, regulations etc. ... 12 2.8.3 Relevant regulations ... 12 3

FUNCTIONAL DESCRIPTION ... 13 3.1 ELECTRONIC OVERVIEW... 13 3.1.1 Power Board (ref. 6.8) ... 13 3.1.2 AC/DC (ref. 6.9) ... 13 3.1.3 DC/DC (ref. 6.10) ... 14 3.1.4 Interface... 16 3.1.5 MMI Board ... 16 3.1.5.1 3.1.5.2 3.1.5.3 3.1.5.4 3.1.5.5

Top Level (ref. 6.2)...16 Buck Regulator (ref. 6.3) ...17 Interface for LED Panel (ref. 6.4) ...17 MCU (ref. 6.5) ...18 Vacuum Sensor Amplifier (ref. 6.6) ...19

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PRO-P16-0001 Rev E 3.1.5.6 3.1.5.7 3.1.5.8 3.1.5.9 3.1.5.10 3.1.5.11

3.1.6 3.1.7 3.1.8 3.1.8.1 3.1.8.2

4

Switch Interface & Battery Power Interface (ref. 6.7) ...20 Temperature ...22 Vacuum Sensor...22 NTC vs. Vacuum Sensor temperature ...23 Charging ...25 Switches ...27

Battery Board ... 29 LED Foil ... 30 Internal Cables ... 30 Power – MMI: ...31 Battery – MMI:...31

MECHANICAL CONSTRUCTION ... 33 4.1 PARTS & ASSEMBLY OVERVIEW ... 33 4.2 PUMP AND MOTOR ... 37 4.3 DISASSEMBLY/ASSEMBLY ... 37 4.3.1 Opening the Unit: ... 37 4.3.2 Exchange of the Power PCB: ... 38 4.3.3 Exchange of the Pump: ... 38 4.3.4 Exchange of the MMI PCB: ... 38 4.3.5 Exchange of the display: ... 38 4.3.6 Exchange of the spring for the selector: ... 38 4.3.7 Assembling the unit: ... 38

5

SERVICE AND MAINTENANCE ... 39 5.1 EXCHANGE OF WEAR AND TEAR PARTS IN THE PUMP... 39 5.1.1 Annual maintenance ... 39 5.1.2 3 years’ service ... 40 5.2 TROUBLESHOOTING ... 41 5.2.1 Overflow ... 41 5.3 PARTS LIST: ... 43

6

CIRCUIT & BLOCK DIAGRAMS ... 44 6.1 LSU BLOCK DIAGRAM ... 44 6.2 MMI BOARD, TOP LEVEL ... 45 6.3 MMI BOARD, BUCK REGULATOR ... 46 6.4 MMI BOARD, INTERFACE FOR LED PANEL ... 47 6.5 MMI BOARD, MCU ... 48 6.6 MMI BOARD, VACUUM SENSOR AMPLIFIER ... 49 6.7 MMI BOARD, SWITCH INTERFACE & BATTERY POWER ... 50 6.8 POWER BOARD, TOP LEVEL... 51 6.9 POWER BOARD, AC/DC FLYBACK CONVERTER... 52 6.10 POWER BOARD, DC/DC FORWARD CONVERTED ... 53

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1

General

The information provided in this manual is limited to what is required for checking, maintenance and board replacement. The intended users of this manual are technical personnel who have been trained in the safe and proper servicing of the LSU. Detailed information regarding controls, operation and capabilities of the suction unit can be found in the Direction for Use that was shipped with the product. This Technical Manual assumes you are familiar with the controls and with the basic operations. The information of this manual is subject to changes without notice. Laerdal Medical shall not be liable for errors contained herein or for incidental or consequential damage in connection with the furnishing, performance, or use of this manual.

LSU w/Disposable Bemis Canister (US only)

LSU w/Serres System

LSU w/Reusable Canister

Important: After opening the pump for any service and repair, a Performance Verification has to be performed ref. “Performance Verification for Laerdal Suction Unit (LSU), Att 1 to 00002339”.

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2

Technical Specification

2.1

Overview

The LSU electronics consists of three PCB’s (Power Bd., MMI Bd. and Battery Bd.), internal cables, and a Front Panel (LED foil). Main features:  Operation from a 12V / 2Ah Nickel Metal Hydride (NiMH) battery  Operation and charging from an external AC power supply (110-240VAC 50/60 Hz).  Operation and charging from an external DC power source (12-28VDC).  The external power source has priority over the internal battery.  When two external power sources are connected, the AC has the highest priority.  An LSU in “OFF” mode automatically enters charging mode if connected to an external power source.  Fast charging (80% capacity in 3 hrs.) 2.1.1

Power Board

The Power Board incorporates two separate galvanic isolated power supplies, one AC/DC converter and one DC/DC converter. Both supplies are able to supply power to the LSU during 1) operation and 2) charging. The Power Bd. output is a “raw” DC voltage of roughly 18 – 20 V. 2.1.2

MMI Board

The MMI Board includes a C system for control of all functions in the LSU. The two main functions of the C software are 1) Suction control and 2) Charging control. During suction the C controls both flow and vacuum applied to the patient (according to the pre-set flow/vacuum level). During charging The C provides efficient charging of the internal battery. The motor is supplied from the external power source whenever the unit is connected to either an external AC or a DC supply. Simultaneous charging and operation from external power is not possible. 2.1.3

Battery Board

The Battery Board connects the battery to the MMI Bd. This board also includes a communication port, RS-232 (logic levels not RS232 levels), for C programming, calibration, assembly testing and future software upgrades. 2.1.4

Main Rotary Switch

The LSU main rotary switch consists of three optical switches and a micro switch placed on the MMI Bd. The micro switch disconnects the battery if the internal SLA battery is the only

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available power source AND the LSU is in “Off” position. The position of the main rotary switch (i.e. decoding of the optical receivers) decides both the flow and the vacuum parameters. 2.1.5

Front Panel

The LSU is equipped with a Front Panel (LED foil) with indicators and a test button. The Front Panel has a vacuum indicator bar graph that indicates the vacuum applied to the patient. The foil also has LEDs indicating ”ON”, “External power”, “Error” and remaining battery capacity. 2.1.6

Block Diagram

NiMH

Figure 1

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2.2

Power Supply

2.2.1

Battery

Voltage/capacity:

12 V / 2Ah

Type:

Nickel Metal Hydride (NiMH) battery

Size (h*l*w):

62.0 mm * 182.0 mm * 23.85 mm

Weight:

380 g +/- 50 g

Battery lifetime:

Replace the battery when it does not pass the Battery Quality Check (ref. DfU) or after 3 years, whichever comes first.

Fuse Type:

5A / 125V (slow)

2.2.2

Environmental conditions

Operating/Charging Temperature: 0°C (32°F) to +40°C (104°F) Recommended Charging Temperature: 15°C (59°F) to +25°C (77°F) Long term Storage Temperature: 0°C (32°F) to +40°C (104°F) Max. 24 hour Storage Temperature: -30°C (-22°F) to +70°C (158°F) Humidity (Operating & Storage): 5 – 95% RH non-condensing

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2.2.3 -

2.2.4

Battery charging Only use batteries approved by Laerdal Medical To maintain satisfactory operation of the battery, it is recommended to place the LSU on continuous charge when not in use Fast charging i.e. 80% restored capacity in 3 hrs. (fast charging function at 20C). Full capacity within 24 hours. Temperature compensated charging voltage.

AC Mains

The AC Mains supply is a switch mode power supply that is part of the Power Board. The AC/DC supply converts 110-240VAC to a 20VDC output. The output voltage is a raw voltage for the Buck converter on the MMI board. A fully electrical isolation barrier between the primary circuit and the applied part that may come in contact with the secondary part (due to filter failure) is ensured by the use of transformers and opt couplers. A 2-pin type appliance inlet according to IEC 60320-1 is used as AC input. Rating: Classification: Dimensions and Compatibility: Lifetime: 10 years) Other: Fuse type: Varistor operating voltage: Input voltage range: Input frequency:

2.2.5

250VAC / 10A according to IEC 60320-1 6 Class II, cold conditions according to IEC 60320-1 7.1 Standard sheet C18 according to IEC 60320-1 9 > 3600 cycles (one connection / disconnection daily for UL/CSA approval 2A / 250VAC (slow) 275V 100 VAC to 240 VAC +10/-15 % 50 or 60  3 Hz (100 - 240VAC),

According to IEC 60601-1:

The equipment is so designed that 1 second after disconnection of the plug the voltage between the supply pins of the plug and between either supply pin or the enclosure does not exceed 60V. Output voltage:

20.0 VDC +1.0/-0.5 VDC

Max input power occurs at 85VAC input voltage and is at a load of [email protected]: 59W  4W

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2.2.6

DC Mains

The DC Mains supply is a switch mode power supply that is part of the Power Board. The DC/DC supply converts 12-28VDC to an 18VDC output. The output voltage is raw voltage for the Buck converter on the MMI board. A fully electrical isolation barrier between the primary circuit and the applied part that may come in contact with the secondary part (due to filter failure) is ensured by the use of transformers and opt couplers. A 2-pin type custom designed appliance inlet according to IEC 60320-1 is used as DC input. Lifetime:

> 3600 cycles (one connection/ disconnection daily for 10 years)

Keying / polarity indication: Other: Fuse type:

Yes UL/CSA approval 5A / 125V (slow)

Varistor operating voltage:

40V

The keying of the connector will protect the electronics against wrong polarity while using cables supplied by Laerdal. Input voltage range: 12VDC to 28VDC 10 % Max input power occurs at 12VDC input voltage and is at a load of [email protected]: 59W  4W Output voltage: Average output power, Paverage @ 18.2VDC: Peak output power, Ppeak @ 18.2VDC:

18.2 VDC +0.5 / -1.0 VDC approx. 27.0W 45.0W

Note: These values are given for the “500+” setting of the LSU.

2.2.7

Indicators

2.2.7.1 General The Front Panel (LED foil) has 18 LEDs: - One “Operation” indicator - One “External power” indicator - One “Error” indicator

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-

Four LEDs indicating “Remaining Battery Capacity”, “Low Battery” and “Charging”. Eleven LEDs indicating “Vacuum level”

2.2.7.2 Operation Colour: Max current (pr. LED): At D.C. 1/8 and 2ms pulse: Controlled by the C:

Green Max 80mA Yes

2.2.7.3 External Power Colour: Max current: Controlled by the C:

Green 20mA - continuous No

2.2.7.4 Error Colour: Max current: Controlled by the C:

Red 20mA - continuous Yes

2.2.7.5 Battery Capacity and Charging Number of LEDs: Colour: Pulse width: Duty cycle: Max current (pr. LED): At D.C. 1/8 and 2ms pulse: Controlled by the C:

Four Green 2ms 1/8 Max 80mA Yes

2.2.7.6 Vacuum Indicators: Number of LEDs: Colour: Pulse width: Duty cycle: At D.C. 1/8 and 2ms pulse: Continuous: Controlled by the C:

Eleven Green 2ms 1/8 Max 80mA Max 20mA Yes

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2.3

Vacuum

2.3.1

Vacuum sensor A piezoresistive pressure sensor, Honeywell No. 22PCCFB6G, is used to measure the vacuum during operation.

2.3.2

Vacuum range: Accuracy: Voltage output range: AD_VAC_SENS voltage tolerance:

0 - 550mmHg  20 mmHg 0.5 – 4.5 V  0.15 V

Sensitivity shift compensation (0 < t < 45°C):

- 0.22 % / °C

Vacuum Valve The vacuum is controlled using the C and an air valve. During free flow the valve is closed. The C opens the valve when the pre-set vacuum is exceeded. An open valve results in a leakage that decreases the vacuum. Type: Operational voltage: Power consumption: Current consumption:

Normally Closed (NC) +5 V 1.2W 210mA

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2.4

Flow

12sl/min at 80 mmHg, 25sl/min at 500+ mmHg 2.5

Noise

46 dBA at 80 mmHg, 56 dBA at 500+mmHg 2.6

Size

l*w*d: 315 mm (12,4 in) x 330mm (13 in) x 160 mm (6,3in) 2.7

Weight

4 kg (8.9 lbs.) including battery 2.8

Classification

2.8.1

Various classifications of LSU

-

“Electrically Powered Suction Equipment” according to NS-EN ISO 10079-1 (1999)

-

“For field and transport use” according to NS-EN ISO 10079-1 (1999) “High vacuum / high flow” according to NS-EN ISO 10079-1 (1999) “Class II type BF” according to IEC 60601-1 “Splash-proof IP34D” according to EN 60529 (2013) Risk class IIA according to MDD (93/42/EEC), annex IX, rule 2, 11.

2.8.2

Other approvals, regulations etc. CE marking according to Medical Device Directive (93/42/EEC) FDA: 510(k) registration UL/CSA approval Japanese approval Australian approval (Tick It system)

-

2.8.3

Relevant regulations 

Medical Device Directive (93/42/EEC) (European Union and EEA-countries)



FDA Quality System Regulation (United States of America)

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3

Functional Description

3.1

Electronic Overview

3.1.1

Power Board (ref. 6.8)

The Power Board includes two switch mode power supplies. The AC/DC supply converts 110-240VAC to a 20VDC output, and the DC/DC supply converts 12-28VDC to an 18VDC output. The output voltages from both supplies are raw voltages for the Buck converter on the MMI board. A fully electrical isolation barrier between the primary circuit and the applied part that may come in contact with the secondary part (due to filter failure) is ensured by the use of transformers and optocouplers.

3.1.2

AC/DC (ref. 6.9)

The AC/DC converter is based on the switching regulator IC TOP227Y (U6) from Power Integration. The regulator has a built-in switching power-FET. Power input is from an AC mains connector. The converter is protected against over voltage by varistor RV1 (275V) and a 1.5A fuse, F1, limits the current drawn. Inductors L3, L9 and common mode inductor L2 together with capacitors C32 and C33, provide EMC protection. The mains voltage is rectified and filtered in BR1 and C30. This voltage is applied through the transformer primary to the regulator.

The transformer T2 has one primary and two secondary windings. One secondary winding produces the output voltage while the other generates power to the regulator (U6). The regulator has three connections. The Control pin is a combined power supply pin and feedback from the output (regulated) voltage. Source is the SOURCE-terminal on the internal power-FET transistor and is connected to GND. Drain is the DRAIN-terminal on the powerFET and is connected to the “low side” of the primary winding of the transformer. At start-up the regulator is for a short period supplied from the rectified mains. When the converter has started, the regulator IC will get power and feedback from the one of the secondary windings, via the optocoupler, U7. The other secondary winding produces the output voltage. The output is rectified by diode D8 and filtered in C28 and C40. Controlling the voltage on the ‘Control’-pin of the regulator regulates the output voltage. The output voltage is divided through resistors R35, R34 and R5 to provide a voltage to the reference-pin of U3. U3, LM431, is an adjustable zener/regulator. When the reference input, pin2, reaches 2.5V the regulator starts to conduct.

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A current through the LED of the optocoupler results, the transistor of the optocoupler starts to conduct and the voltage of the Control pin will increase leading to reduction of the output voltage. The output voltage is thus regulated to a voltage producing 2.5V at the reference-pin of U3. D19 and D20 limit the voltage peaks applied to regulator. Snubber components C39, R20, R21, R41 and R42, as well as C34, reduce EMC. To protect the output rectifier, D8, the tranzorber, D2, is used. Snubber components C11, R12, R14, R29 and R30 reduce voltage spikes and EMC. The diode D9 prevents current to enter this circuit when there is no AC mains present. C38, 1nF/4kV safety type capacitor, provides an AC path between primary and secondary GND. This capacitor is important for EMC reduction.

3.1.3

DC/DC (ref. 6.10)

The DC/DC converter is based on the switching regulator SI9114A, from Vishay Siliconix, with an external switching power-FET, Q1. Power input is from a DC power source of 12V-28V. The converter is protected against over voltage by varistor RV2 (40V) and a 5A fuse, F2, limits the current drawn. The unit’s electronics is protected from wrong polarity by diode D14, but the fuse will blow. Common mode filters L4 and L1 together with capacitors C15 and C14 and C20 provide EMC protection. C9 and C16 provide energy storage.

To power the regulator U9, power-FET driver and the feedback, a 12V supply is requested. The adjustable version of LM2931 does not take the high input voltage that can occur at the highest input voltages, a fixed 5V regulator is, therefore, used. To obtain 12V, the ground pins are ‘lifted’ by means of the zenerdiode D21. R4 provides current to the zener and C3 reduces the impedance over the zener. The diode D1 limits the positive voltage of GND-pins of the regulator, relative to the output pin, which can occur for a short period after the input supply has been removed. This prevents any problem in getting the regulator started if there is a voltage “bouncing” while connecting power. R51 and C52 set the operation frequency of the switching regulator. In this application the operating frequency is about 220kHz. Output from the switching regulator is the on/off signal to the switching transistor, Q1. The two-stage buffer consisting of Q10-Q13 buffers this signal. R13 slows the gate drive somewhat, for EMC reasons.

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R49 produces a signal proportional to the current through Q1. This signal is filtered by R56 and C44 and fed back to the regulator, this signal is an important regulation parameter. The switching regulator gets feedback from the output voltage via the optocoupler, U10. Components R44-R47 and C49-C49 set the operation point, amplification and stability for the regulator feedback op-amp. The transformer, T1, has two windings on the primary side. They have the same number of turns. The one connected between pin 2 and 4, carries the switched current while the other one together with D22, dissipate the energy from the rest inductance. D10, R11, R58 and C57 form a snubber network to reduce peak voltage on Q1. Also, snubber network C53, R8 and R51 help reduce peak voltage on Q1.

One secondary winding on the transformer produces the output voltage. Double-diode D4 is a combined rectifier and freewheeling diode. Inductor L6 is power storage for the feed forward converter. C17 and C18 are output filtering and energy reservoir. The freewheeling diode is protected by a tranzorbers D5 and D6. Two resistors are connected in series with the tranzorbers to share some of the energy dissipated. Also, there are snubbers on both halves of D4, consisting of C13, R9 and R19 for the rectifier and C56, R10 and R10 for the freewheeling diode. The snubbers have influence on voltage peaks on D4 and Q1 as well as on EMC.

Feedback from output voltage to the regulator is through the optocoupler. The output voltage is divided through resistors R3, R6, R7 and R18 to provide a voltage to the reference-pin of U2. U2, LM431, is an adjustable zener/regulator. When the reference input, pin2, reaches 2.5V the regulator starts to conduct. A current through the LED of the optocoupler results and the transistor of the optocoupler starts to conduct. The voltage across R48 will increase and hence the voltage on the regulator’s feedback terminal (FB), leading to reduction of the output voltage. The output voltage is thus regulated to a voltage producing 2.5V at the reference-pin of U2. The diode D7 prevents current to enter this circuit when there is no DC mains present. C54, 10nF/250V safety type capacitor, provides an AC path between primary and secondary GND. This capacitor is important for EMC reduction.

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3.1.4

Interface

AC and DC input: Connector type: Molex Art. No: RFQ9ER47017 (Custom design) Pin # 1 2 3 4

Signal Name

Description AC input AC input + DC input - DC input

Power Board to MMI Board: Connector type: Molex Art. No: 43650-0203 Pin # 1 2 3.1.5

Signal Name GND 18/20V

Description GND 18 / 20 V output to MMI Bd.

MMI Board

The MMI Board includes a micro-controller, a switch mode voltage regulator (Buck converter) for motor control and battery charging, a switch mode 5V supply, a magnet air valve and a vacuum sensor for vacuum control, and drivers for the LEDs on the front panel (LED-foil). An EEPROM contains 1) Set up parameters, 2) Calibration data, 3) Operating data. The MMI Board also contains circuits to detect the position of the Operating Knob. The micro controller:  Regulates the motor speed according to selected level, by adjusting the Buck converter and measuring the Buck regulator output voltage.  Keeps the vacuum at or below the selected level, by measuring the actual vacuum and letting in air through the air valve, when required.  Estimates the remaining battery capacity.  Controls charging of the internal battery whenever the unit is in OFF position and there is external power connected.  Presents measured vacuum and battery status by means of LEDs on the front panel. The MMI Board electronics are explained in order of schematic sheets.

3.1.5.1 Top Level (ref. 6.2) This sheet gives an over view of schematic sheets with inter sheet signal connections. Also, shown are the input and output connectors (except the LED foil connector), transistor Q1 that switches the MOTOR on/off, transistor Q12 that switches the AIR VALVE on/off,

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resistor R68 that is used to measure the charging current to the battery and D14 that prevents current to flow back from battery to the charging circuit. 3.1.5.2 Buck Regulator (ref. 6.3) Power line 9-20V is supplied from Power Board when external power is connected. If no external power is connected, 9-20V is powered from battery if Operation Knob is in any position other than “0”. A voltage level detector detects an input voltage of more than about 15V, turning on Q3 and, thereby, turning ON the LED_EXT_PWR on the front panel. Motor and charging voltage is regulated by the Buck converter, which consists of regulator, U1, inductor L1, freewheel diode D5, input and output capacitors. The voltage divider R12, R22, R92 and R13 define absolute maximum output voltage. The regulator will always try to regulate the output voltage to get 1.21V at the feedback terminal (FB). By adding a voltage to the voltage divider, the regulator can be forced to reduce the output voltage to maintain the feedback terminal at 1.21V. The microcontroller generates a PWM signal according to required voltage. The PWM signal is demodulated/LP-filtered in U3 to present a DC voltage at the summing point, R25. The diode, D2, prevents the demodulator from drawing a current from the summing point and thus increases output voltage. C48 blocks a DC high from a faulty microcontroller, to result in maximum high voltage from the Buck regulator. Diode D18 limits the negative voltage on the base of Q2. Q2 shapes the incoming pulse-train to square 5V pulses for the demodulator/filter. Regulator U2, with surrounding components, also makes up a buck converter. Divider R17 and R11 set the output voltage to nominally 5.25V. This is the system’s “+5V” supply. 3.1.5.3 Interface for LED Panel (ref. 6.4) This sheet shows the LED drivers. The microcontroller controls the LED matrix by means of 4 column and 4 row signals. Resistors R30-R33 limits current through the LEDs. Capacitors on all lines provide ESD protection. LED_ERROR and LED_EXT_PWR have separate controls. The LED_ERROR is controlled by the microcontroller, while the external voltage detector controls LED_EXT_PWR. The signal TEST_BTN is a HIGH if test button on the front panel is pressed.

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3.1.5.4 MCU (ref. 6.5) The microcontroller is a PIC16C77 controller from Microchip. This is a 44-pin PLCC chip with an 8-bit A/D converter, 8K x 14 Words Program Memory and 368 x 8 RAM. The table below gives the pin assignments: Pin# 1 2 3 4 5 6 7

Pin Name NC xMCLR/Vpp RA0/AN0 RA1/AN1 RA2/AN2 RA3/AN3/Vref RA4/T0CK1

Signal Name

Function

Note

AD_MOTOR_VOLTAGE AD_BATT_TEMP AD_BATT_VOLTAGE Vref HW_VER_BIT0

8 9

RA5/xSS/AN4 RE0/xRD/AN5

AD_VAC_SENS AD_CURRENT

10

RE1/xWR/AN6

9-20V

11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

RE2/xCS/AN7 VCC GND OSC1/CLKIN OSC2/CLKOUT RC0/T1OSO/TICK1 NC RC1/Y1OSI/CCP2 RC2/CCP1 RC3/SCK/SCL RD0/PSP0 RD1/PSP1 RD2/PSP2 RD3/PSP3 RC4/SDI/SDA RC5/SDO RC6/TX/CK NC RC7/RX/DT

AI from Buck reg. AI from NTC at battery AI from battery +5V reference for ADC DI - HW address Bit 0 (LSB) AI from vacuum sensor AI from charging current measurement AI from PWR Bd. and battery voltage. AI from +5V (½)

30 31 32 33 34 35 36 37 38

RD4/PSP4 RD5/PSP5 RD6/PSP6 RD7/PSP7 GND VCC RB0/INT RB1 RB2

+5V 0-5V 0-5V 0-5V +5V GND 0-5V 0-5V 0-5V

RELEASE_VALVE

CLK In CLK Out DO to air valve

0-5V +5V GND 4MHz 4MHz L/H

PWM_VOLTAGE HW_VER_BIT1 SCL LED_COL_1 LED_COL_2 LED_COL_3 LED_COL_4 SDA HW_VER_BIT2 TXD

PWM to Buck. Reg. DI - HW address Bit 1 Serial Clock for I2C bus DO for LED control DO for LED control DO for LED control DO for LED control Serial Data for I2C bus DI - HW address Bit 2 Transmit – Serial Com.

4kHz GND L/H L/H L/H L/H L/H L/H L/H L/H

RXD

Receive – Serial Com.

L/H

LED_ROW_1 LED_ROW_2 LED_ROW_3 LED_ROW_4 GND VCC ON_SWITCH TEST_BTN MOTOR

DO for LED control DO for LED control DO for LED control DO for LED control

L/H L/H L/H L/H GND +5V L/H L/H L/H

VCC GND

DI from SW1 DI from Test Button DO to connect the motor to the Buck. Reg.

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39

RB3

LED_ERROR

DO to switch ERROR LED

L/H

40

NC

41

RB4

OPTO_ON

L/H

RB5 RB6 RB7

OPTO_C OPTO_B OPTO_A

DO to activate opto sensors DI from opto sensor C DI from opto sensor B DI from opto sensor A

42 43 44

L/H L/H L/H

Transistors Q10 and Q14 only connects the AD_BATT_VOLTAGE to the controller when the +5V is present, i.e. an external power supply is present or the Operating Knob is in any position other than “0”. U5 provides a 5V-reference voltage for the A/D converter. NTC1 is a termistor used to measure temperature and located close to the vacuum sensor. Temperature is used to compensate the vacuum measurement and the battery charging voltage. All signals to the A/D converter are filtered and some also have a voltage divider to adjust the input voltage to the A/D converter range of 0-5V. Y1 is a 4MHz resonator controlling the processor clock. Diode D19 prevents programming voltage to enter the +5V during in circuit programming. Diode D3 and resistor R79 provides a limitation of Vcc input to the controller. Diodes D16 and D17 provide over voltage protection for the serial communication inputs. EEPROM, U8, keeps various parameters and operation/service data. The controller communicates with the EEPROM on an I2C bus. Resistors R97-R99 and R101-R103 are used to indicate the HW and/or SW version. 3.1.5.5 Vacuum Sensor Amplifier (ref. 6.6) The sensor output is amplified in a differential amplifier with fixed amplification of about 30, U7A-U7C. Op-amp U7D provides additional adjustable amplification as well as LP-filtering. POT1 is a dual digital potentiometer. POT1A is used to adjust the offset of the sensor. POT1B is used to adjust the amplification in U7D to produce the requested output signal for maximum vacuum. POT1C is the communication part of the potentiometer. The microcontroller communicates with the potentiometer on an I2C bus. During calibration the offset is set to 0.5V and the amplification is adjusted to give 4.5V output at 550mmHg.

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PRO-P16-0001 Rev E

3.1.5.6 Switch Interface & Battery Power Interface (ref. 6.7) To determine the position of the Selector Knob the optical sensors D10-D12 are utilized. The Selector Knob has several flags that pass through the sensors as the knob is operated.

Each position of the Selector Knob generates a unique combination of sensor output OPTO_A, OPTO_B and OPTO_C. The microcontroller turns the sensor LEDs on only during read-periods, by means of transistor Q8. Decoding of the optical receivers: Opto A 0 1 0 1 1 0 0 1

Opto B 1 0 0 0 1 0 1 1

Opto C 1 0 1 1 0 0 0 1

Hex value 0x03 0x04 0x01 0x05 0x06 0x00 0x02 0x07

“Setting” O 80 120 200 350 500 N/A N/A

The Selector Knob also, operates the micro-switch SW1. With the Selector Knob in position “0”, the micro-switch shorts signal ON_SWITCH to GND. If an external supply is connected, this will start battery charging. Any other positions of the Selector Knob will switch SW1 to connect between 1 and 3, this opens Q21 and the battery will be connected to “9-20V” through D6. Regardless of power source, the unit will be switched ON and operation is according to the position of Selection Knob. If an external supply is connected, a voltage higher than the battery voltage is applied to “9-20V” and no power is drawn from battery. D4 and D7 limit power supply voltage for U4 (and U7 sheet 5) to a maximum of about 14.2V. Charging current measurement is built around op-amp U4. Input (I_sens+ and I_sens-) is taken from across resistor R68. Resistors R5, R6, R9 and R10 are high precision to achieve high common mode rejection in the differential amplifier, U4A. The ratio between R5,R6 and R9,R10 ensures that that the common mode voltage on the input of U4A is sufficiently lower than the power supply to the op-amp. U4D provides additional amplification. Voltage divider R90 and R88 together with U4B generate a reference voltage, one volt above GND, for the amplifier. This ensures that the signal passed to the A/D converter is always positive, even when op-amp offset and common mode “signal” caused by resistor errors will produce a negative voltage.

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