DA5546 [TEMIC]

Telecom Circuit, 1-Func, CMOS, PDSO20, SOIC-20;


型号：	DA5546
厂家：	TEMIC SEMICONDUCTORS
描述：	Telecom Circuit, 1-Func, CMOS, PDSO20, SOIC-20 电信光电二极管电信集成电路
文件：	总5页 (文件大小：54K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

DA5546

Single Chip Ultrasonic Alarm Processing Circuit

Description

The DA5546 is a single chip ultrasound signal The synchronous demodulator system which monitors

processing IC, intended for automotive applications for both the magnitude and phase of the return signal gives

detecting intrusion into an ultrasound field where a significant improvement in sensitivity and noise

automatic gain control (AGC) is not required or in rejection compared to more basic systems. The logic

applications with a user sensitivity adjustment. The IC level alarm output of the DA5546 enables it to be part

was developed as an Application Configurable System of a microprocessor controlled security system. The

Cell (ACSC), either to be used as a stand alone circuit, DA5546 is implemented in a 1.2um double poly double

or as part of a larger custom circuit designed to suit metal CMOS process and runs from a single 5V supply

specific application requirements. The DA5546 with a basic power consumption of 5mW (excluding

contains all the circuit functions necessary to implement transmit sensor power). The device is available in a 20

an advanced low power, high sensitivity ultrasonic pin SOIC package.

movement detection system.

Features

· Complete stand alone system

· A low noise 40kHz preamplifier for the receive

sensor

· Sensitive to both amplitude and phase disturbances

· 5mW active power consumption

· Synchronous demodulator to extract Doppler tones

caused by moving objects

· A master clock oscillator with an external ceramic

resonator

· Second order low-pass and high-pass filters to define

the Doppler frequency range and reduce the effect of

thermal air movement inside the vehicle

· Threshold detector and time averaging integrator

reduces the effect of transient noise and wind

· Compact 20 pin SOIC package

· A clock divider and transmit sensor driver

System Overview

The front-end bandpass filter removes out of band noise 0.1m/s to 2m/s. Further gain is applied to the signal

and interference, particularly the effects of EMC, and together with a second high-pass/low-pass filter, to

prevents amplifier overload.

The output of the remove the effects of slow air movement caused by

amplifier is fed to a synchronous demodulator. This convection currents inside the vehicle. The output of

gives an output that is proportional to both the the second filter is monitored by a window comparator

amplitude and phase of the return signal giving a with +/-200mV thresholds: any Doppler tones larger

significant increase in sensitivity, as the phase of the than this will cause the integration capacitor connected

return signal varies much more rapidly than the to the CEV pin to be charged up. When this capacitor

amplitude when intrusions occur. An additional benefit is charged to 2.5V the alarm output pin ALR will go

is the high degree of rejection of wideband noise since high. If no Doppler tones are present then the

only signals coherent with the transmitter excitation are integration capacitor is discharged at a much slower

recognised.

rate. With a capacitor of 47nF fitted between the CEV

pin and ground, Doppler tones must be present for a

least 400ms before the ALR output goes high.

The demodulator output is high-pass and low-pass

filtered and amplified to extract the Doppler tones

caused by moving object with velocities in the range of

Dialog Semiconductor

Rev. B, 4-October-97

DA5546

Functional Block Diagram

VDD

VSS

IBIAS

AGND

Bias

V_mid

Generator

TXH

TXL

4MHz

Oscillator

Clock

Divider

RXH

RXL

EMC Filter

20-80KHz

40KHz

Preamplifier

Synchronous

Demodulator

PSD

BOP

Doppler

Filter

+0.2

FIN

Window

comparator

BIN

ALR

30dB gain

-0.2

Event integrator

CEV

CAL

CAH

FOP

Application Notes

A single 5 volt power supply is required. The resistor The DA5546 must be used with 40kHz piezoelectric

connected between IBIAS and VDD is used to define heads. These are available from several manufacturers

the internal operating bias currents. The chip alone in a wide variety of sizes and styles. In general the

typically takes approximately 1mA without a transmit smaller transducers have lower sensitivity. The DA5546

head connected, and 2 - 3 mA with a typical transmit chip provides a differential output drive at the TXH &

head. The chip generates its own mid-rail reference TXL pins to drive the transmit head at 10 volts pk-pk.

supply of 2.5V which is brought out at the A

pin The polarity of the transmit head is unimportant. If a

GND

for decoupling (mandatory). Most of the internal reduced output can be accepted, then the transmit head

analog circuitry is referenced to this voltage. The may be connected between either TXH or TXL and 0

operating current of the internal circuitry is set by the volts to reduce the power consumption.

resistor between the I

pin and the 5 volt supply.

BIAS

The receive head should be connected with the case or

'low' side to RXL and the isolated or 'high' side to RXH.

The DA5546 requires a 4MHz ceramic resonator which

may be of the two or three pin variety. If the resonator

has two pins (as shown) then the correct loading

capacitors must be connected as specified by the

resonator manufacturer. If a three pin resonator is used

then these capacitors are included internally and the

user simply needs to ground the centre pin.

Note that the RXL pin is connected to the A

reference voltage internally and should not be

GND

connected to 0V externally.

Dialog Semiconductor

Rev. B, 4-October-97

DA5546

Application Notes (Continued)

The capacitor connected between pins CEV and ground

sets the integration time. A value of 47nF will give

approximately 400ms. Intrusions must persist for this

time before the ALR pin goes high.

increase both the series 15nF capacitor connected to

CAH and the parallel 4.7nF capacitor between FIN

and FOP. To increase the lower Doppler limit,

decrease the parallel 47nF capacitor between CAH

and CAL and decrease the series 100nF capacitor

connected to PSD.

Convection current effects cause air movement which

increase rapidly as the interior temperature of the car

rises. Opening the ventilation outlets on the dashboard

also increases these problems. The effect of air

movement is to create large Doppler signals in the 0 to

1 Hz frequency band, whereas signals caused by

intrusions are in the 10 to 170 Hz band. Since the air

movement effects occupy a different frequency band

than the wanted signals, they can be removed by

filtering. However, these signals can be very much

larger than the wanted signals (up to 50dB), so

discrimination is improved with a higher order filter.

For single vehicle type applications, a fixed gain may

be employed as the interior parameters of the

application will not change. In this case, the 20kW

variable resistor may be omitted and the other filter

components optimised.

- Figure 3 shows a 3rd order active filter with variable

gain using the uncommitted buffer op-amp available

at pins BIN and BOP. This will give improved

discrimination between air movement and slow

moving objects over the passive filters shown in

Figure 2. To decrease the upper Doppler limit,

increase both the series 15nF capacitor connected to

CAH and the parallel 2.2nF capacitor between FIN

and FOP. To increase the lower Doppler limit,

decrease the parallel 47nF capacitor between CAH

and CAL and decrease the two series 100nF

capacitors connected to PSD.

In the diagrams below (Figures 2 & 3) various

configurations of air movement filter are shown :

- Figure 2 shows a simple 2nd order passive high-pass

filter with variable gain. This is necessary for correct

operation of the system as it provides good

discrimination between air movement and slow

moving objects. To increase the sensitivity, increase

the value of the 180kW resistor and decrease the value The ALR pin is the active high alarm output and is both

of the parallel 4.7nF capacitor connected between FIN TTL and CMOS level compatible.

and FOP. To decrease the upper Doppler limit,

47nF

40KHz

receiver

33pF

BIN

BOP

4MHz

CEV

RXH

A_VSS

ceramic

resonator

33pF

A_VDD

RXL

+5V

AVDD

IBIAS

VDD

10mF

15nF

CAH

AGND

10mF

47nF

AVSS

CAL

PSD

VSS

TXH

68KW

40KHz

100nF

4.7nF

transmitter

FIN

TXL

ALR

FOP

180KW

ALR

20K

W min

Figure 2 - Simple Filter

Dialog Semiconductor

Rev. B, 4-October-97

DA5546

47nF

33pF

40KHz

receiver

100k

BIN

BOP

4MHz

ceramic

resonator

CEV

RXH

A_VSS

33pF

A_VDD

RXL

+5V

AVDD

IBIAS

VDD

10mF

15nF

CAH

AGND

10mF

47nF

AVSS

CAL

PSD

VSS

TXH

130KW

40KHz

100nF

transmitter

FIN

TXL

ALR

FOP

330KW

2.2nF

ALR

20KW min

Figure 3 - Extra Air Movement Rejection Filter with Variable Gain

Pin Description

Pin Number^.

Pin Name

BIN

Functional Description

Input to buffer amplifier

CEV

RXH

RXL

IBIAS

CAH

CAL

PSD

Integrator filter capacitor

Receive transducer signal input

Receive transducer signal common

Bias current input for internal circuitry

2nd LP/HP capacitor

2nd HP capacitor

Demodulator output to 1st filter

1st filter input

FIN

FOP

1st filter output

ALR

TXL

TXH

VSS

Active high alarm output

Transmit transducer anti-phase drive

Transmit transducer in-phase drive

Negative supply

AGND

VDD

Internally derived mid-rail reference

Positive supply

Oscillator input from ceramic resonator

Oscillator output to ceramic resonator

Not connected

BOP

Output from buffer amplifier

Dialog Semiconductor

Rev. B, 4-October-97

DA5546

Absolute Maximum Ratings

V_DDto V_SS______________________________________-0.3V, + 7V

All other pins ___________________________ V_SS- 0.3V, V_DD+0.3V

Continuous power dissipation __________________________500mW

Operating temperature range _____________________-40°C to +85°C

Storage temperature range _____________________ -65°C to +1 60°C

Lead temp (Soldering, 10 sec) __________________________+300°C

Stresses beyond those listed under 'Absolute Maximum Ratings' may

cause permanent damage to the device. These are stress ratings only and

functional operation of the device at these or any other conditions beyond

those indicated in the operational sections of the specification is not

implied. Exposure to absolute maximum rating conditions for extended

periods may affect device reliability.

Electrical Characteristics

Specified at V

= +5V and V = 0V and T

= 25°C, F

= 4MHz, I

= 4µA

amb

xtal

bias

Parameter

Min

0.2

Max

Units

Return signal at RXH pin for correct operation

Input impedance at RXH pin

mV rms.

200

±220

2.6

Window comparator thresholds

AGND out voltage

±180

2.4

1.0

4.0

TXH, TXL output swing with 1kW load

V_DDsupply current without Tx head

1.5

NB. Typical transmit heads will add 0.5 - 5mA to the supply current depending on the head type and whether

differential or single ended drive is used.

About TEMIC Semiconductors

TEMIC is the microelectonics enterprise of Daimler- Circuit) is the key to true system integration. TEMIC

Benz. The Semiconductor Division of TEMIC includes Semiconductors’ years of experience in mixed signal

Telefunken Semiconductors, Siliconix, Matra MHS, ASIC technology gives our customers the ability to

and Dialog Semiconductor. A leader in the design of achieve the integrated solutions their systems need.

semiconductor

products

for

communications, TEMIC Semiconductors’ extensive mixed signal design

automotive, computer, hi-rel, industrial, and consumer and manufacturing expertise was acquired vial the

applications, TEMIC’s worldwide semiconductor specialist company Dialog Semiconductor, which

operations include ISO-9001 certified manufacturing became part of the TEMIC group in 1992. TEMIC

facilities in Europe, the United States, and Asia/Pacific. Semiconductors is a leading supplier of mixed signal

Sales are handled by the worldwide TEMIC network technology, and we support all types of mixed signal

and by regional sales representatives and distributors.

solutions in CMOS, from the initial idea through to

volume production.

Successfully combining analog and digital functions on

the same ASIC (Application-Specific Integrated

This Publication is issued to provide outline information only which (unless agreed by Dialog Semiconductor in writing) may not be used, applied or

reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to products or services concerned. Dialog

Semiconductor reserves the right to alter without notice the specification , design, price or conditions of supply of the product. Customer takes note that

Dialog Semiconductor’s products are not designed for use in devices or systems intended for supporting or monitoring life nor for surgical implants into

the body. Customer shall notify the company of any such intended use so that Dialog Semiconductor may determine suitability. Customer agrees to

indemnify Dialog Semiconductor for all damages which may be incurred due to use without the company’s prior written permission of product in such

applications.

Dialog Semiconductor

Rev. B, 4-October-97

DA5546 [TEMIC]

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