WO1998013922A1 - Circuit servant a proteger des circuits electroniques contre une inversion de tension d'entree - Google Patents

Circuit servant a proteger des circuits electroniques contre une inversion de tension d'entree Download PDF

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Publication number
WO1998013922A1
WO1998013922A1 PCT/US1997/016466 US9716466W WO9813922A1 WO 1998013922 A1 WO1998013922 A1 WO 1998013922A1 US 9716466 W US9716466 W US 9716466W WO 9813922 A1 WO9813922 A1 WO 9813922A1
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WO
WIPO (PCT)
Prior art keywords
battery
terminal
electrically connected
circuit
input voltage
Prior art date
Application number
PCT/US1997/016466
Other languages
English (en)
Inventor
Kenneth E. Garde
Original Assignee
Becton Dickinson And Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Becton Dickinson And Company filed Critical Becton Dickinson And Company
Priority to AU44204/97A priority Critical patent/AU4420497A/en
Publication of WO1998013922A1 publication Critical patent/WO1998013922A1/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
    • H02H11/002—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result in case of inverted polarity or connection; with switching for obtaining correct connection
    • H02H11/003—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result in case of inverted polarity or connection; with switching for obtaining correct connection using a field effect transistor as protecting element in one of the supply lines

Definitions

  • the present invention relates to a circuit for protecting circuitry in an electronic device, such as an iontophoretic drug delivery device, against the large flow of reverse current when a battery is installed backwards in the device.
  • a battery reversal protection circuit is required because a large reverse current could damage the electronic circuitry in the device and may cause the device to act unpredictably.
  • Iontophoretic devices are used to introduce drugs by means of an electric current into the tissues of the body for therapeutic purposes.
  • One important characteristic of these devices is that the amount of drug delivered to the patient is directly proportional to the amount of electric current applied. By controlling the amount of current over time, the amount of drug delivered to the patient can be precisely and advantageously controlled. Accordingly, iontophoretic devices have, in recent years, become an increasingly important means for administering therapeutic agents as they provide this and other advantages not achievable by other methods of administration, such as by passive drug patches, by ingestion or by injection through the skin.
  • Iontophoretic devices use at least two electrodes which are in contact with the skin of the patient's body; a first electrode, the active electrode, delivers the ionic substance or drug into the body by iontophoresis, and the second electrode, the return electrode, closes the electrical circuit that includes the first electrode and the patient's body.
  • a battery provides the electrical current used to drive the drug from the first electrode through the skin and into the tissue of the patient.
  • An electronic controller circuit electrically connected between the electrodes and the battery controls the amount of current applied to the electrodes over time and thus the amount of drug delivered to the patient
  • the electronic controller must be small, lightweight and portable so it can be carried easily by nurses and be worn by the patient comfortably. It uses low power circuitry so that most of the battery's energy can be used to deliver drugs to the patient in the iontophoresis circuit Thus, power losses in the electronic controller circuitry, including any caused by the battery reversal protection circuit, must be kept as small as possible
  • the controller must also be capable of delivering a large dosage of drugs in a short time period, which requires a large amount of current
  • any battery reversal protection circuit must be capable of operating efficiently during large current surges
  • the electronic controller, including the battery reversal protection circuit must be cost-effective so the iontophoretic device can compete in the marketplace with other methods of drug delivery
  • a battery BT1 when installed correctly, that is, in a forward direction, and has a voltage greater than the cutin voltage of a diode Dl, the diode is said to be in a forward-bias state.
  • the diode In this forward-bias state, the diode has a forward voltage drop approximately between 0 2 and 1 0 volts, typically around 0 3 volts for a Schottky diode and 0 6 volts for a silicon diode, and thus conducts current in a forward direction, shown by arrow 10
  • Fig 1 A shows the cathode 12 of the diode Dl connected to the cathode 2 of the battery BT1, the anode 1 1 of the diode Dl connected to a terminal 22 of electronic circuitry 20, and the other terminal 21 of the electronic circuitry connected to the anode 1 of the battery BT1.
  • IB shows the case in which the anode 1 1 of the diode D2 is connected to the anode 1 of the battery BT1.
  • the diode has a very large reverse resistance on the order of several hundred kiloohms or more. Only an extremely low amount of current is conducted in the reverse direction 13, thus protecting the circuitry connected to the diode.
  • the voltage drop across a diode generally varies more than the voltage drop across a MOSFET. This is because the diode has a higher on-resistance. This relatively greater variation in voltage drop makes a diode poorly suited for use in low voltage applications where the current variation is greater, such as in the above-described iontophoretic device, since the diode will experience a relatively larger change in voltage drop as current increases. This is generally known to those in the art as "load regulation”.
  • the single diode circuits shown in Figs 1 A and IB prevent a large forward flow of current when the battery is reversed thus protecting the connected circuitry. In doing this, however, the diode also turns off the connected circuitry.
  • Another well-known circuit using a different technique for protecting circuitry against battery reversal is a four diode or transistor bridge rectifier circuit, as described in U.S. Patent 4,473,757 (Farago et al.).
  • the bridge rectifier circuit of Farago et al. accepts either a positive or negative polarity input voltage, and by switching off certain diodes or transistors, depending on the input voltage polarity, generates a positive polarity output voltage.
  • the connected circuitry will not be damaged by a large reverse current if the battery is installed backwards, because only forward currents can be generated by the bridge rectifier. Unlike the single diode, however, the connected circuitry will operate when the battery is installed backwards.
  • Farago et al. shows MOS field effect transistors (MOSFETs) in the bridge rectifier circuit.
  • MOSFETs MOS field effect transistors
  • a minimum of four MOSFETS may be used in the bridge rectifier, but only if the MOSFETs are made using costly silicon-on-sapphire technology.
  • a diode or MOSFET bridge rectifier as shown in Farago et al. requires at least four times as many components than a single diode or transistor circuit, and is relatively expensive.
  • the bridge rectifier requires additional circuitry to overcome the forward biasing of the intrinsic pn diodes of the MOSFETs.
  • eight MOSFETs must now be used to eliminate the problems caused by the forward biasing of intrinsic pn diodes between the respective sources and substrates of the MOSFETs (see col. 4, lines 8-49, of Farago et al ).
  • a battery reversal protection circuit that includes a single MOSFET transistor.
  • a circuit for protecting load circuitry from a reversed application of an input voltage, the load circuitry having a first and a second terminal.
  • the circuit includes an n-channel MOSFET transistor having a gate, a source and a drain.
  • the gate is to be normally electrically connected to the positive terminal of the input voltage.
  • the gate is electrically connected to the first terminal of the load circuitry.
  • the drain is to be normally electrically connected to the negative terminal of the input voltage.
  • the source terminal is electrically connected to the second terminal of the load circuitry.
  • a switch having a first and a second terminal is provided in the circuit.
  • a p-channel MOSFET is used instead of an n-channel MOSFET.
  • Figs. 1A, IB and 1C depict conventional diode circuits for protecting circuitry against battery reversal
  • Figs. 2A and 2B depict circuits using a single N-MOSFET transistor in accordance with a first embodiment of the present invention
  • Figs. 3A and 3B depict circuits using a single P-MOSFET transistor in accordance with a second embodiment of the present invention.
  • Fig. 4 depicts a conventional Schottky diode circuit used in a first and second comparative tests
  • Fig. 5 depicts a circuit corresponding to the first embodiment of the present invention used in the first and second comparative tests.
  • Fig 6 depicts a circuit corresponding to the second embodiment of the present invention used in the first and second comparative tests
  • Fig. 7 depicts a circuit corresponding to the first embodiment of the present invention used in a third comparative test DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • the present invention relates to electronic medical devices, and in the preferred embodiments, iontophoretic drug delivery devices. However, it is to be understood that this invention may be applied to any electronic circuitry, and in particular any battery-operated circuitry.
  • the present invention is most advantageously applicable to low voltage devices in which the prevention of battery reversal is a critical issue, such as to ensure safe operation of the device First Embodiment In the first embodiment of the invention, as shown in Figs.
  • a single n-channel MOSFET (NMOS) transistor Ql is used to provide protection against battery reversal as follows As shown in Fig 2A, gate 201 of NMOS Ql is electrically connected to both the anode 1 of the battery BT1 and the first terminal 21 of the load circuitry 20 Drain 202 of NMOS Ql is electrically connected to the cathode 2 of the battery, and source 203 of NMOS Ql is electrically connected to the second terminal 22 of the load circuitry 20
  • NMOS Ql When the battery is correctly installed, as shown in Fig. 2A, NMOS Ql is fully enhanced because the voltage of gate 201 is pulled up above the voltage of the source 203 by an amount approximately equal to the battery voltage V Of course, the battery voltage V is assumed to be greater than the minimum voltage require to turn the transistor "on" Thus, current will flow from source 203 to drain 202 in a forward direction as shown by arrow 200 However, if a battery is installed backwards with its cathode connected to gate 201 and its anode connected to drain 203, as shown in Fig 2B, NMOS Ql stays "off' because the gate voltage is negative with respect to the source voltage. The intrinsic drain-source diode is reverse-biased When the NMOS Ql is off, only a minute current flows in the reverse direction 230, and thus the load circuitry 20 will not be damaged.
  • Figs. 3 A and 3B show a second embodiment of the present invention using a p-channel MOSFET (PMOS) Q2.
  • PMOS p-channel MOSFET
  • the gate 301 of PMOS Q2 is electrically connected to both the cathode 2 of the battery BT1 and the second terminal 22 of a load circuitry 20.
  • Drain 302 of PMOS Q2 is electrically connected to the anode 1 of the battery and source 303 of NMOS Q2 is electrically connected to the first terminal 21 of the load circuitry 20 and the substrate of PMOS Q2.
  • the operation of the second embodiment is substantially similar to the first embodiment.
  • the gate voltage is pulled down below the source voltage by an amount equal to the battery voltage, and current flows in a forward direction 300 from the drain 302 to the source 303.
  • the gate 301 is at a positive voltage with respect to the source 303, Q2 is off and only a minute current flows in the reverse direction 330, thus protecting the load circuitry 20.
  • a single NMOS or a single PMOS transistor thus provides protection to the load circuitry against battery reversal.
  • Fig. 4 depicts a conventional diode circuit using a Schottky diode D4 (1N5819 made by General Instrument).
  • the anode 404 of the battery BT2 is connected to the anode 401 of the diode D4, the cathode 402 of the diode is connected to one end of a resistor load 400 of R L ohms ( ⁇ ) and the cathode 405 of the battery BT2 is connected to the other end of the resistor load 400.
  • Figs. 5 and 6 depict circuits using NMOS and PMOS transistors respectively corresponding to the first and second embodiments of the present invention. In Fig.
  • gate 501 of the NMOS transistor Q5 (TN0104N8 made by Supertex) is connected to the battery anode 404 and to one end of the resistor load 400, the drain 502 is connected to the battery cathode 405, and the source 503 and the transistor's substrate are connected to the other end of the resistor load 400.
  • gate 601 of the PMOS transistor Q6 (TP0104N8 made by Supertex) is connected to the battery cathode 405 and to one end of the resistor load 400, the drain 602 is connected to the battery anode 404, and the source 603 is connected to the other end of the resistor load 400.
  • the battery BT2 has a voltage V j .
  • the voltage V 0 across the resistor load 400 was measured. From this measurement, the voltage drop V d across the diode D4 (or across the drain and source in the case of the MOSFETs) and the circuit current I were respectively calculated using the formulas:
  • V 0 Measurements of V 0 were taken for resistor loads R L of 10 K ⁇ , 1 K ⁇ , 200 ⁇ , 100 ⁇ , 50 ⁇ and 20 ⁇ and for battery voltages V ; of 3 volts and 2.5 volts.
  • test results for the diode D4 and the NMOS transistor Q5 are shown below in Table A, and for the diode D4 and the PMOS transistor Q6 in Table B.
  • a resistor load R L equal to 1 k ⁇ and a battery voltage V, of 3 volts (see Table A)
  • both the n- and p-MOSFETs Q5 and Q6 respectively significantly outperform the diode D4 when the load resistance R L is relatively high. These performance characteristics are similar to the case in which the battery voltage V ; is 2.5 volts.
  • the reverse current was measured when the battery was installed into the circuit of Fig. 7 backwards.
  • V 0 was measured to be less than 0.1 millivolts, generating a reverse current of less than 0.1 miUiamperes.
  • V 0 was measured to be approximately 0.5 millivolts, generating a reverse current of approximately 0.5 nanoamperes.
  • the n-MOSFET Q7 is effectively an open switch and will thus protect the load circuitry.
  • a switch 800 may be placed in the gate line, that is, between the gate 201 or 301 and the node N between the battery BTl and the load circuitry 20, to facilitate on/off control of the device.
  • Fig. 8 A shows a switch used with NMOS transistor Ql
  • Fig. 8B shows a switch used with PMOS transistor Q2.
  • This switch can be either a mechanical or an electronic switch, or any well-known device that functions as a switch.
  • embodiments of the present invention may be made of discrete components or may be part of an integrated circuit.

Landscapes

  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

L'invention se rapporte à un circuit de protection de circuits de charge électroniques contre une installation inverse d'une batterie. Ledit circuit comprend un transistor MOF à canal N ou un transistor à canal P, qui a une grille, une source et un drain. La grille est normalement connectée électriquement à l'anode (dans un transistor MOF à canal N) ou à la cathode (dans un transistor MOF à canal P) de la batterie, et est connectée électriquement à une extrémité des circuits de charge. Le drain est normalement connecté électriquement à l'autre extrémité de la batterie. La source est connectée électriquement à l'autre extrémité des circuits de charge. Si la batterie est installée correctement, le transistor MOF fonctionne comme un commutateur fermé, qui permet au courant de se diriger vers les circuits de charge; si la batterie est installée inverse, le transistor MOF fonctionne comme un commutateur ouvert et empêche qu'un flux important de courant inverse n'endommage les circuits de charge.
PCT/US1997/016466 1996-09-26 1997-09-17 Circuit servant a proteger des circuits electroniques contre une inversion de tension d'entree WO1998013922A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU44204/97A AU4420497A (en) 1996-09-26 1997-09-17 Circuit for protection of electronic circuitry against input voltage reversal

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US72138096A 1996-09-26 1996-09-26
US08/721,380 1996-09-26

Publications (1)

Publication Number Publication Date
WO1998013922A1 true WO1998013922A1 (fr) 1998-04-02

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PCT/US1997/016466 WO1998013922A1 (fr) 1996-09-26 1997-09-17 Circuit servant a proteger des circuits electroniques contre une inversion de tension d'entree

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WO (1) WO1998013922A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1076362A2 (fr) * 1999-08-13 2001-02-14 Micronas GmbH Circuit à semi-conducteur
DE102005031478A1 (de) * 2005-07-04 2007-01-11 Conti Temic Microelectronic Gmbh Netzteil für Kfz-Steuergeräte mit einem Schaltwandler
WO2019086285A1 (fr) * 2017-11-03 2019-05-09 Continental Teves Ag & Co. Ohg Circuit de protection contre l'inversion de polarité, procédé de fonctionnement du circuit de protection contre l'inversion de polarité et utilisation correspondante

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3535788A1 (de) * 1985-09-03 1986-02-20 Siemens AG, 1000 Berlin und 8000 München Verpolungsschutz fuer schaltungsanordnungen
EP0305936A2 (fr) * 1987-08-31 1989-03-08 National Semiconductor Corporation Protection de circuits intégrés MOS contre l'inversion des bornes de la batterie
DE3741394A1 (de) * 1987-12-07 1989-06-15 Siemens Ag Schaltungsanordnung zum schutz vor verpolungsschaeden fuer lastkreise mit einem mos-fet als schalttransistor
WO1994003952A1 (fr) * 1992-07-31 1994-02-17 Siemens Aktiengesellschaft Protection contre les inversions de polarite avec element a surface reduite

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3535788A1 (de) * 1985-09-03 1986-02-20 Siemens AG, 1000 Berlin und 8000 München Verpolungsschutz fuer schaltungsanordnungen
EP0305936A2 (fr) * 1987-08-31 1989-03-08 National Semiconductor Corporation Protection de circuits intégrés MOS contre l'inversion des bornes de la batterie
DE3741394A1 (de) * 1987-12-07 1989-06-15 Siemens Ag Schaltungsanordnung zum schutz vor verpolungsschaeden fuer lastkreise mit einem mos-fet als schalttransistor
WO1994003952A1 (fr) * 1992-07-31 1994-02-17 Siemens Aktiengesellschaft Protection contre les inversions de polarite avec element a surface reduite

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1076362A2 (fr) * 1999-08-13 2001-02-14 Micronas GmbH Circuit à semi-conducteur
EP1076362A3 (fr) * 1999-08-13 2001-06-20 Micronas GmbH Circuit à semi-conducteur
US6556400B1 (en) 1999-08-13 2003-04-29 Micronas Gmbh Reverse polarity protection circuit
DE102005031478A1 (de) * 2005-07-04 2007-01-11 Conti Temic Microelectronic Gmbh Netzteil für Kfz-Steuergeräte mit einem Schaltwandler
WO2019086285A1 (fr) * 2017-11-03 2019-05-09 Continental Teves Ag & Co. Ohg Circuit de protection contre l'inversion de polarité, procédé de fonctionnement du circuit de protection contre l'inversion de polarité et utilisation correspondante
US11664659B2 (en) 2017-11-03 2023-05-30 Continental Teves Ag & Co. Ohg Polarity-reversal protection arrangement, method for operating the polarity-reversal-protection arrangement and corresponding use

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Publication number Publication date
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