CN201259693Y - Wake-up circuit used for ETC vehicle-mounted unit - Google Patents

Abstract

The utility model provides a wake-up circuit used for an ETC vehicle-mounted unit. The wake-up circuit is a two-stage signal processing structure, wherein, the first stage uses the low-power integrated operational amplification and realizes mV weak signal amplification; and the second stage adopts a low-power integrated comparator and realizes the further amplification of the wake-up signal to make the signal digitized. The utility model adopts the low-power integrated operational amplification and the low-power integrated comparator; compared with the common wake-up circuit of the ETC vehicle-mounted unit, the utility model can work at low power consumption which is less than 7 microamp and can receive the wake-up detection signals with the frequencies varying from 14kHZ to 256kHz, so as to easily ensure the performance consistency of the wake-up circuit and facilitate mass production.

Description

A kind of wake-up circuit that is used for the ETC board units

Technical field

The utility model is about intelligent transportation field, especially in regard to a kind of wake-up circuit of ETC board units.

Background technology

The ETC system mainly comprises roadside unit and board units, is used for the charge automatically of not stopping in highway, bridge and tunnel.The research and development starting of domestic ETC system is than later, and in May, 2007, country just formally issued relevant criterion.

The wake-up circuit of ETC board units often adopts discrete component to realize, as bipolar transistor, field effect transistor etc., this method for designing makes wake-up circuit comparatively complicated, and power consumption is bigger, is unfavorable for that battery powered ETC board units works long hours.In addition, because the index parameter discreteness of discrete component is bigger, be difficult to guarantee the consistance of circuit performance, the quiescent point that can only adjust transistor or field effect transistor reaches uniformity in product performance, has caused very big difficulty for producing in batches like this.

The utility model has used the two-stage signal treatment circuit of low-power consumption integrated transporting discharging and low power consumption comparator to realize the arousal function of ETC board units, and power consumption is extremely low, and is easy to guarantee the consistency of performance of wake-up circuit, is beneficial to batch process.

The utility model content

This wake-up circuit has designed a kind of the two poles of the earth signal processing circuit structure, has adopted the integrated circuit of low-power consumption, has used peripheral cell seldom, adapt to and wake the rectified signal wide frequency range up, low in energy consumption, and guarantee easily the consistency of performance of wake-up circuit to be beneficial to batch process.

The circuit structure schematic diagram as shown in Figure 1.The principle of work of this wake-up circuit is summarized as follows:

This wake-up circuit is a kind of two-stage signal Processing Structure, and the first order has been used the low-power consumption integrated transporting discharging, has realized the amplification of millivolt level feeble signal; The low-power consumption integrated comparator has been used in the second level, realizes the further amplification to wake-up signal, and makes its digitizing.

Wake-up circuit first order signal Processing.Wake rectified signal up and receive the reverse input end of low-power consumption integrated transporting discharging U50 by coupling capacitance C52, resistance R 56.Supply voltage is received the input end in the same way of amplifier U50 after resistance R 51, R52 dividing potential drop, as reference voltage.Rectified signal through U50 has been exaggerated 20 times, and enlargement factor A computing formula is as follows:

$A=\frac{R61}{R56}$

Wake-up circuit second level signal Processing.Received the reverse input end of low power consumption comparator U51 by coupling capacitance C53 by the rectified signal after the first order amplification.Supply voltage is received the input end in the same way of comparer U51 after resistance R 53, R54 dividing potential drop, when the rectified signal of U51 backward end greater than the magnitude of voltage of end in the same way, wake-up signal end output high level then, on the contrary output low level has realized the digitizing of wake-up signal.Board units relies on the variation edge that detects this high-low level, realizes arousal function.

This wake-up circuit has not only been realized the arousal function at the frequency discrimination signal of wide region, and low in energy consumption, and working current is less than 7 microamperes, and the very easy consistance that guarantees the wake-up circuit performance.

Description of drawings

Fig. 1 is a circuit structure schematic diagram of the present utility model;

Embodiment

The utility model cooperates the arousal function of finishing board units as the part in the ETC system onboard unit circuit with radio circuit and board units CPU.

Claims (4)

1. wake-up circuit that is used for the ETC board units is characterized in that:

This utility model is a kind of two-stage signal Processing Structure for the ETC board units has designed a kind of wake-up circuit, and the first order has been used the low-power consumption integrated transporting discharging, has realized the amplification of millivolt level feeble signal; The low-power consumption integrated comparator has been used in the second level, realizes the further amplification to wake-up signal, and makes its digitizing.

2. circuit according to claim 1 is characterized in that having used two-stage signal treatment circuit structure.

3. circuit according to claim 1 is characterized in that first order signal Processing used low-power consumption integrated transporting discharging MAX9910.

4. circuit according to claim 1 is characterized in that second level signal Processing used low-power consumption integrated comparator MAX9021.

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