Device and method for operating a device

Abstract

A device (200) is provided. The device has at least one processor (222) configured to implement the following: performing an operation using energy provided by an external reading device (104), wherein, during the performance of the operation, an input voltage of a near-field radio receiver (228) is regulated to a predetermined first input voltage value, and, after completion of the operation, while the near-field radio receiver (228) is still in the electromagnetic field generated by the external reading device (104), regulating the input voltage (VRX) of the near-field radio receiver (228) to a second input voltage value that is lower than the first input voltage value.

Description

[0001] The invention relates to a device and a method.

[0002] Security controllers in contactless applications, e.g. in a contactless device such as a smartcard, will be damaged in the long run if a relatively high voltage is frequently applied to their antenna contact pins.

[0003] However, such a high voltage is used to achieve high communication performance, e.g., a high signal strength for sending a signal or a high reception quality of the signal in the contactless device.

[0004] The stress caused by the high voltage at the safety controller (or generally at a chip connected to the antenna) must be taken into account as a parameter when calculating an expected lifetime.

[0005] An example from the state of the art concerns a payment transaction using a contactless payment card. Such a payment transaction typically takes less than half a second after the card is inserted into a reading area (also referred to as the operating area) and has several transmission phases. The card is usually removed from the reading area relatively quickly once the transaction is complete.

[0006] Occasionally, however, a card remains in the reading area for longer than half a second. For example, the card might not be removed for one or two seconds. In this case, the reader typically performs repeated presence checks, which involve high voltages. These high voltages reduce the lifespan of the (contactless) card.

[0007] In various embodiments, a device is provided. This device can be a contactless chip device, for example a chip card, or another portable contactless chip device such as a wearable.

[0008] In various embodiments, the device is configured so that the high voltage is only provided as an input voltage when it is actually required by the device. In various embodiments, the device can be configured to initially provide the high voltage (for example, when the card is activated, e.g., by inserting the card into the reading area of ​​an active reader) and then reduce the voltage level after an operation is completed. In various embodiments, the device can be configured to initially provide a comparatively low voltage (for example, when the card is activated, e.g., by inserting the card into the reading area of ​​an active reader), which is sufficient, for instance, to determine whether an operation requiring a high voltage is planned, and if so, to selectively increase the voltage.After the operation is completed, the voltage level can be reduced again.

[0009] By limiting the periods in which the input voltage of the device is comparatively high to those periods in which the high input voltage is actually needed for operations to be performed, the service life of the (contactless) device is increased.

[0010] In various embodiments, the device comprises at least one processor configured to implement the following: performing an operation using energy provided by an external reading device, wherein, during the execution of the operation, an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value, and, after completion of the operation while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, regulating the input voltage of the near-field radio receiver to a second input voltage value that is lower than the first input voltage value.

[0011] The device can thus be configured in various embodiments to provide the high input voltage at the near-field radio receiver only for those operations (e.g., providing authentication data, financial transactions, etc.) that require very good (e.g., optimal) signal quality, and to immediately reduce the input voltage provided at the input of the near-field radio receiver to a value sufficient for basic functions, such as presence verification or the transmission of an "operation completed" signal.

[0012] In various embodiments, a device is provided which has at least one processor configured to implement the following: performing an operation using energy provided by an external reading device, wherein, during the performance of the operation, an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value, and, if a voltage increase criterion is met, while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, regulating the input voltage of the near-field radio receiver to a second input voltage value that is higher than the first input voltage value.

[0013] This makes it possible to operate the device generally with a less harmful, lower input voltage of the near-field radio receiver, and only to raise the input voltage of the near-field radio receiver to a required value when a relevant operation is planned that requires high, e.g. optimal, transmission quality.

[0014] Exemplary embodiments of the invention are shown in the figures and are explained in more detail below.

[0015] They show Fig. 1A an illustration of the use of a chip card according to various examples; Fig. 1B and Fig. 1C each a flowchart for the use of the chip card according to different implementation examples; Fig. 2A and Fig. 2B each a schematic representation of a device according to different embodiments; Fig. 3 a schematic representation of a chip card according to various embodiments; and Fig. 4A and Fig. 4B each contains a flowchart for the use of the device according to different embodiments.

[0016] The following detailed description refers to the accompanying drawings, which form part thereof and illustrate specific embodiments in which the invention can be implemented. In this context, directional terminology such as "top," "bottom," "front," "back," "anterior," "rear," etc., is used with reference to the orientation of the described figure(s). Since components of embodiments can be positioned in a number of different orientations, the directional terminology serves only for illustration and is in no way limiting. It is understood that other embodiments may be used and structural or logical modifications may be made without deviating from the scope of protection of the present invention.It is understood that the features of the various exemplary embodiments described herein can be combined with one another, unless specifically stated otherwise. The following detailed description is therefore not to be interpreted in a limiting sense, and the scope of protection of the present invention is defined by the appended claims.

[0017] Within the scope of this description, the terms "connected," "attached," and "coupled" are used to describe both direct and indirect connections, direct or indirect links, and direct or indirect couplings. In the figures, identical or similar elements are labeled with identical reference symbols where appropriate.

[0018] Fig. Figure 1A shows an illustration 100 of a use of a chip card 102 according to various embodiments, which includes a device 200 according to various embodiments.

[0019] Fig. 1B and Fig. Figures 1C and 120 each show a flowchart for the use of the chip card 102 according to different embodiments, and Fig. 2A and Fig. Figures 2B each show a schematic representation of a device 200 according to different embodiments.

[0020] The device 200 can have at least one processor 222. The processor 222 can, for example, be a microprocessor or have a microprocessor, or another type of suitable processor.

[0021] The 222 processor can, for example, be designed as a voltage controller and / or as a shunt regulator.

[0022] The processor 222 can be electrically connected to (two) inputs 230. The inputs 230 can be chip inputs, for example, inputs of a chip 220 for providing near-field communication (NFC). Accordingly, the chip can also be referred to as an NFC chip 220.

[0023] The device 200 can further comprise a near-field radio receiver 228, which is configured to provide an input voltage V at the inputs 230. RX to provide.

[0024] In Fig. 2A and Fig. Figure 2B illustrates the near-field radio receiver 228 as an antenna. The near-field radio receiver 228 (e.g., the antenna) can be configured in various embodiments to interact directly with an external reading device 104 or an electromagnetic field generated by it, thereby receiving energy which can be supplied at the inputs 230.

[0025] In various cases, the near-field radio receiver 228 (e.g., the antenna) can be configured to interact indirectly with the reading device 104 or an electromagnetic field generated by it, thereby receiving energy that can be supplied at the inputs 230. For example, the near-field radio receiver 228 (e.g., the antenna) can be inductively coupled to an additional antenna (not shown), e.g., a booster antenna, which in turn couples electromagnetically to the electromagnetic field supplied by the reading device 104.

[0026] For communication with the external reading device, the device may further include a modulator / demodulator 224, which may be configured to modulate the input voltage V RX , which is received at inputs 230, to demodulate into a data signal, and conversely, to modulate a transmitted data signal onto the input voltage.

[0027] The device 200 may also include additional components, for example a second processor 226 or (micro)controller for application control.

[0028] In the case of security-relevant applications, such as payment transactions and / or authentication processes, the second processor 226 can, for example, be a so-called security processor set up for cryptographic procedures.

[0029] In various embodiments, the processor 222, the second processor 226 and / or the modulator / demodulator 224 can be implemented as separate elements, integrated, or together as a system-on-chip (the system-on-chip is in Fig. 2B schematically depicted, where the processor 222, the second processor 226 and the modulator / demodulator 224 are connected to each other; corresponding connections are also present when designed as separate elements - e.g. on separate chips).

[0030] The processor 222 can be configured in various embodiments to implement the execution of an operation using energy provided by an external reading device 104 (e.g., in the form of an electromagnetic field, for example, in accordance with near-field communication standards), wherein an input voltage V is applied during the execution of the operation. RX The near-field radio receiver 228 is regulated to a predetermined first input voltage value.

[0031] Unless the processor 222 and the second processor 226 are integrated, the implementation of the execution can be understood as the processor 222 enabling or supporting the operation to be performed by the second processor 226.

[0032] If the processor 222 and the second processor 226 are integrated, for example by having the voltage regulation and the execution of the operations performed by a single processor 222, 226, then implementing the execution can be understood as performing.

[0033] The operation can, for example, be an operation typically provided for via near field communication, such as a financial transaction (like a payment process) and / or involve authentication.

[0034] The operation can, for example, require a comparatively high input voltage V RX required to ensure high signal quality.

[0035] The operation can be performed using the second processor 226 in various cases.

[0036] The processor 222 can also be configured, after the operation has ended, while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, to supply the input voltage V RX to regulate the near-field radio receiver 228 to a second input voltage value that is lower than the first input voltage value.

[0037] The completion of the operation can be indicated to processor 222, for example, by means of the second processor 226.

[0038] The 222 processor can be configured to regulate the input voltage V RX to the second (lower) input voltage value essentially immediately after the operation is completed, e.g., essentially immediately after receiving the information that the operation is finished. A typical duration for performing an operation might, for example, range from 100 ms to about 5 s.

[0039] In particular, operations with a long overall duration may have several sub-operations, which make it possible to additionally reduce the input voltage to the second input voltage value between the execution of the individual sub-operations.

[0040] The control system can, for example, involve controlling a shunt which, depending on the control signal, either removes or does not remove a predetermined amount of excess energy.

[0041] Fig. Figure 1B illustrates the procedure described above: When the device 200 (in this case as part of a chip card 102) is inserted into a reading area of ​​the external reading device, the input voltage is initially provided at the higher first input voltage value (for example, in a range of about 4 V to about 5 V, for example, in a range of about 4.2 V to about 4.8 V, for example, by about 4.5 V), the operation is completed, and then the input voltage is reduced to the second, lower input voltage value (for example, in a range of about 3 V to less than 4 V, for example, in a range of about 3.2 V to about 3.8 V, for example, by about 3.5 V).

[0042] In the time arrow on the left, the period in which the input voltage has the high first value is shown with hatching, and the period in which the input voltage has the lower second value (also known as the "reliability state") is shown with dots.

[0043] After removing chip card 102 (and thus device 200) from the reading area, the input voltage drops to zero volts.

[0044] In various embodiments, a device 200 is provided which corresponds structurally to the device 200 described above.

[0045] Its processor can be configured to implement a (first) operation using energy provided by the external reading device 104, whereby, during the operation, an input voltage of a near-field radio receiver 228 is regulated to a predetermined first input voltage value.

[0046] In contrast to the case described above, the (first) operation can be designed in such a way that it does not require a high input voltage value.

[0047] For example, the first operation may involve charging an internal energy storage device, and / or determining which operation is planned next.

[0048] In other words, in various embodiments, the input voltage can initially be provided at a low input voltage value, which is sufficient for basic applications.

[0049] The processor 222 can further be configured to implement that, when a voltage increase criterion is met while the near-field radio receiver 228 is still in the electromagnetic field generated by the external reading device 104, the input voltage of the near-field radio receiver 228 is regulated to a second input voltage value that is higher than the first input voltage value.

[0050] This means that the input voltage is only increased when there is a need for a higher input voltage, which can be indicated to processor 222, for example, by means of the second processor 226.

[0051] A corresponding illustration can be found in Fig. Figure 1C shows that when the device 200 (again as part of a chip card 102) is inserted into a read area of ​​the external reader 104, the input voltage is initially provided at the lower first input voltage value (for example, in a range of approximately 3 V to less than 4 V, for example, in a range of approximately 3.2 V to approximately 3.8 V, for example, by approximately 3.5 V) and a (first) operation is performed. After determining that a higher input voltage is required, the input voltage is increased to the second, higher input voltage value (for example, in a range of approximately 4 V to approximately 5 V, for example, in a range of approximately 4.2 V to approximately 4.8 V, for example, by approximately 4.5 V).

[0052] After increasing the input voltage, a second operation can be performed, which may, for example, correspond to the operation described above in connection with Fig. 1B was explained.

[0053] In various embodiments, after the second operation has been completed, the input voltage can be lowered again, similar to the process described in... Fig. 1B explained the procedure.

[0054] After removing chip card 102 (and thus device 200) from the reading area, the input voltage drops to zero volts.

[0055] In the time arrow on the left, the period in which the input voltage has the high second value is shown with hatching, and the period in which the input voltage has the lower first value is shown with dots.

[0056] In various embodiments, the processor can further be configured to detect an additional state of the device, to compare the detected additional state with an additional voltage matching criterion, and, if the additional voltage matching criterion is met, to adjust the input voltage.

[0057] The additional condition may, for example, be the current lifetime of the device, which may be below or equal to a maximum value for a tolerable lifetime or above it; the temperature of the device 200, for example the processor 222, which should not exceed a maximum temperature; and / or the number of unsuccessful attempts to perform the operation, where exceeding a maximum number may not be useful.

[0058] The device 200 may have appropriate sensors and / or memory, for example one or more temperature sensors for measuring the temperature, memory for storing a lifetime counter and / or for summing up unsuccessful attempts during the execution of the operation, or similar functions that depend on a reduction of the input voltage V RX can benefit.

[0059] In the above-mentioned examples of the additional state, adjusting the input voltage can accordingly result in a decrease in the input voltage.

[0060] In various embodiments, the additional state can include the detection of faulty communication.

[0061] This may mean that the provided input voltage is not high enough to provide sufficient signal quality.

[0062] Accordingly, adjusting the input voltage can result in an increase in the input voltage.

[0063] Fig. Figure 3 is a schematic representation of a chip card 102 according to various embodiments.

[0064] The chip card 102 can be used to control a device 200 according to various embodiments, for example as described above, for example in connection with Fig. 1A to 2B.

[0065] The chip card 102 can further comprise a chip card body 330. The device 200 can be arranged in or on the chip card body 330, for example, embedded in the chip card body 330.

[0066] In various embodiments, the near-field radio receiver 228 can surround a large area of ​​the chip card body, for example as an antenna running along an edge of the chip card body 330, whereas the processor can cover a comparatively small area of ​​the chip card body 330.

[0067] In various embodiments, the near-field radio receiver 228 of the device 200 can also cover a small area, for example, be arranged together with the chip 220 on a chip module. Optionally, a booster antenna can be arranged in the chip card body 330, with which the near-field radio receiver 228 can couple for indirect coupling with the external reading device 104.

[0068] It should be understood that the chip card 102 is representative of a multitude of possible devices that may have the device, for example other wearables such as smartwatches, smart rings or similar.

[0069] Fig. Figure 4A shows a flowchart 400 for the use of the device according to various embodiments, for example a device 200 as described above.

[0070] The method comprises performing an operation using energy provided by an external reading device, wherein during the performance of the operation an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value, (410), and, after completion of the operation, while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, regulating the input voltage of the near-field radio receiver to a second input voltage value which is less than the first input voltage value (420).

[0071] Fig. Figure 4B shows a flowchart 400 for the use of the device according to various embodiments, for example a device 200 as described above.

[0072] The method comprises performing an operation using energy provided by an external reading device, wherein during the performance of the operation an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value (411), determining whether a voltage increase criterion is met while the near-field radio receiver is in an electromagnetic field of the reading device (421), and if so, regulating the input voltage of the near-field radio receiver to a second input voltage value that is higher than the first input voltage value (431).

[0073] The following is a summary of some examples.

[0074] Exemplary embodiment 1 is a device comprising at least one processor configured to implement the following: performing an operation using energy provided by an external reading device, wherein, during the performance of the operation, an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value, and, after completion of the operation, while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, regulating the input voltage of the near-field radio receiver to a second input voltage value that is lower than the first input voltage value.

[0075] Exemplary embodiment 2 is a device according to exemplary embodiment 1, wherein the operation includes a financial transaction and / or an authentication.

[0076] Exemplary embodiment 3 is a device according to exemplary embodiment 1 or 2, wherein the operation comprises a plurality of sub-operations, wherein the processor is further configured to regulate the input voltage of the near-field radio receiver to the second input voltage value between each of the plurality of sub-operations and to regulate the input voltage of the near-field radio receiver to the first input voltage value for each of the plurality of sub-operations.

[0077] Exemplary embodiment 4 is a device comprising at least one processor configured to implement the following: performing an operation using energy provided by an external reading device, wherein, during the performance of the operation, an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value, and, if a voltage increase criterion is met while the near-field radio receiver is still within the electromagnetic field generated by the external reading device, regulating the input voltage of the near-field radio receiver to a second input voltage value that is higher than the first input voltage value.

[0078] Exemplary embodiment 5 is a device according to exemplary embodiment 4, which is further configured to perform a second operation using energy provided by the external reading device with the second input voltage value.

[0079] Exemplary embodiment 6 is a device according to exemplary embodiment 5, which furthermore, after completion of the second operation, while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, has a regulation of the input voltage of the near-field radio receiver to the first input voltage value.

[0080] Exemplary embodiment 7 is a device according to exemplary embodiment 5 or 6, wherein the second operation includes a financial transaction and / or authentication.

[0081] Exemplary embodiment 8 is a device according to one of the exemplary embodiments 5 to 7, wherein the second operation has a plurality of sub-operations, wherein the processor is further configured to regulate the input voltage of the near-field radio receiver to the second input voltage value between each of the plurality of sub-operations and to regulate the input voltage of the near-field radio receiver to the first input voltage value for each of the plurality of sub-operations.

[0082] Exemplary embodiment 9 is a device according to one of the exemplary embodiments 1 to 8, which further comprises a shunt, wherein the processor is configured to control the input voltage of the near-field radio receiver by controlling the shunt.

[0083] Exemplary embodiment 10 is a device according to one of the exemplary embodiments 1 to 9, wherein the processor is further configured to detect an additional state of the device, to compare the detected additional state with an additional voltage matching criterion, and, if the additional voltage matching criterion is met, to adjust the input voltage.

[0084] Exemplary embodiment 11 is a device according to exemplary embodiment 10, wherein the additional state comprises a group of states comprising or consisting of a current lifetime of the device, a temperature of the device, and a number of unsuccessful attempts to perform the operation.

[0085] Exemplary embodiment 12 is a device according to exemplary embodiment 10 or 11, wherein the adjustment of the input voltage involves a reduction of the input voltage.

[0086] Exemplary embodiment 13 is a device according to exemplary embodiment 10, wherein the additional state includes the detection of faulty communication.

[0087] Exemplary embodiment 14 is a device according to exemplary embodiment 10 or 13, wherein the adjustment of the input voltage involves increasing the input voltage.

[0088] Exemplary embodiment 15 is a device according to one of the exemplary embodiments 1 to 14, wherein the near-field radio receiver has an antenna which is electrically connected to inputs for providing the input voltage and is configured to couple electromagnetically, directly or indirectly, to the external reading device.

[0089] Exemplary embodiment 16 is a chip card comprising a chip card body and a device according to one of the exemplary embodiments 1 to 15.

[0090] Exemplary embodiment 17 is a method for operating a device. The method comprises performing an operation using energy provided by an external reading device, wherein, during the performance of the operation, an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value, and, after completion of the operation, while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, the input voltage of the near-field radio receiver is regulated to a second input voltage value that is lower than the first input voltage value.

[0091] Exemplary embodiment 18 is a method for operating a device. The method comprises performing an operation using energy provided by an external reading device, wherein, during the performance of the operation, an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value, and, if a voltage increase criterion is met while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, the input voltage of the near-field radio receiver is regulated to a second input voltage value that is higher than the first input voltage value.

[0092] Further advantageous embodiments of the device will result from the description of the method and vice versa.

Claims

[1] Device (200) comprising: at least one processor (222) configured to implement the following: • Performing an operation using energy provided by an external reading device (104), wherein, during the performance of the operation, an input voltage of a near-field radio receiver (228) is regulated to a predetermined first input voltage value; and • After the operation has ended, while the near-field radio receiver (228) is still in the electromagnetic field generated by the external reading device (104), regulate the input voltage (V RX ) of the near-field radio receiver (228) to a second input voltage value that is lower than the first input voltage value. [2] Device (200) according to claim 1, wherein the operation includes a financial transaction and / or authentication. [3] Device (200) according to claim 1 or 2, the operation comprises a plurality of sub-operations; wherein the processor (222) is further configured to adjust the input voltage (V) between each of the plurality of sub-operations RX ) of the near-field radio receiver (228) to regulate to the second input voltage value and to adjust the input voltage (V) for each of the plurality of sub-operations RX ) of the near-field radio receiver (228) to regulate to the first input voltage value. [4] Device (200) comprising: at least one processor (222) configured to implement the following: • Performing an operation using energy supplied by an external reading device (104), wherein an input voltage (V) is applied during the performance of the operation RX ) of a near-field radio receiver (228) is regulated to a predetermined first input voltage value; and • if a voltage increase criterion is met while the near-field radio receiver is still in the electromagnetic field generated by the external reading device (104), regulate the input voltage of the near-field radio receiver (228) to a second input voltage value that is higher than the first input voltage value. [5] Device (200) according to claim 4, further comprising: Performing a second operation using energy provided by the external reading device (104) with the second input voltage value. [6] Device (200) according to claim 5, further comprising: After completion of the second operation, while the near-field radio receiver is still in the electromagnetic field generated by the external reading device (104), regulation of the input voltage (V RX ) of the near-field radio receiver (228) to the first input voltage value. [7] Device (200) according to claim 5 or 6, wherein the second operation comprises a financial transaction and / or authentication. [8] Device (200) according to one of claims 5 to 7, wherein the second operation comprises a plurality of sub-operations; wherein the processor (222) is further configured to adjust the input voltage (V) between each of the plurality of sub-operations RX ) of the near-field radio receiver (228) to regulate to the second input voltage value and to adjust the input voltage (V) for each of the plurality of sub-operations RX ) of the near-field radio receiver (228) to regulate to the first input voltage value. [9] Device (200) according to any one of claims 1 to 8, further comprising: a shunt; wherein the processor (222) is set up to control the input voltage (V) by means of the shunt RX ) of the near-field radio receiver (228). [10] Device (200) according to any one of claims 1 to 9, wherein the processor (222) is further configured as follows: to detect an additional state of the device (200); to compare the detected additional state with an additional voltage matching criterion; and if the additional voltage matching criterion is met, the input voltage (V RX ) to adapt. [11] Device (200) according to claim 10, wherein the additional state comprises a group of states comprising or consisting of: a current lifetime of the device (200); a temperature of the device (200); a number of unsuccessful attempts to perform the operation. [12] Device (200) according to claim 10 or 11, wherein the adjustment of the input voltage (V RX ) a reduction in the input voltage (V RX ) exhibits. [13] Device (200) according to claim 10, wherein the additional state includes the detection of faulty communication. [14] Device (200) according to claim 10 or 13, wherein the adjustment of the input voltage (V RX ) an increase in the input voltage (V RX ) exhibits. [15] Device (200) according to any one of claims 1 to 14, wherein the near-field radio receiver has an antenna equipped with inputs for providing the input voltage (V RX ) is electrically conductive and is configured to couple directly or indirectly with the external reading device (104) electromagnetically. [16] Chip card (102), comprising: a chip card body (330); and a device (200) according to any one of claims 1 to 15. [17] Method for operating a device comprising the method: • Performing an operation using energy supplied by an external reading device, wherein, during the performance of the operation, an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value (410); and • After the operation has ended, while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, regulate the input voltage of the near-field radio receiver to a second input voltage value that is lower than the first input voltage value (420). [18] Method for operating a device comprising the method: • Performing an operation using energy supplied by an external reading device, wherein, during the performance of the operation, an input voltage of a near-field radio receiver is regulated to a predetermined first input voltage value (411); and • if a voltage increase criterion is met while the near-field radio receiver is still in the electromagnetic field generated by the external reading device, regulate the input voltage of the near-field radio receiver to a second input voltage value that is higher than the first input voltage value (421, 431).

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