Datasheet

Smart Sensor

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Electrical Characteristics over Recommended Ranges of Supply Voltage

and Operating Free-Air Temperature

PARAMETER TEST COND. MIN TYP MAX UNIT

Input Current BLNK, BINH, INIT** V

= 2.1 V 1 mA

High-level Output Current, I

ECHO, OSC, INIT** V

= 5.5V 100 μA

Low-level Output Voltage, V

, ECHO, OSC, INIT** I

O L

= 1.6 mA 0.4 V

Internal Blanking Interval 2.38 ms

XMIT Drive Signal Duration 1.1 ms

Frequency During 16-pulse OSC output 49.4 kHz

Transmit Period XMIT output 49.4 kHz

Frequency After 16-pulse OSC output 93.3 kHz

Transmit Period XMIT output 0 kHz

Supply Current, During transmit period 2000 mA

After transmit period 100 mA

** INIT is a TTL compatible input for External Triggering; INIT is a TTL compatible output for Internal Triggering

Operation

The Series 600 Smart Sensor has two basic modes of operation: Single-echo mode and multiple-echo mode. The

application of power (V

), the application of the initiate (INIT) input, the resulting transmit output, and the use of the

Blanking Inhibit (BINH) input are basically the same for either mode of operation. After applying power, a minimum of 5

milliseconds must elapse before the INIT signal can be taken high. During this time, all internal circuitry is reset and the

internal oscillator stabilizes. When INIT is raised to a high level, a transmit drive to the ultrasonic sensor (XDCR) occurs.

Sixteen pulses at 49.4 kHz are transmitted from the ultrasonic sensor. At the end of the 16 transmitted pulses, a 200 VDC

bias remains on the ultrasonic sensor (as recommended) for optimum receiving operation.

In order to eliminate the inherent ringing of the ultrasonic sensor after transmitting from being detected as a returning echo,

the Receive (REC) input of the ranging control IC is inhibited by internal blanking for 2.38 milliseconds after the initiate

(INIT) signal. If a reduced blanking time is desired, then the input BINH can be taken high to end the blanking of the

Receive input any time prior to internal blanking. This may be desirable to detect objects closer than 1.33 feet

(corresponding to 2.38 milliseconds) and may be done if ultrasonic sensor damping is sufficient so that ringing is not

detected as a return signal.

Single Echo Mode

In the single-echo mode of operation (Figure 1), all that must be done next is to wait for the return of the transmitted signal,

traveling at approximately 0.9 milliseconds per foot out and back. The returning signal is amplified and appears as a high

logic level echo output. The time between INIT going high and the Echo (ECHO) output going high is proportional to the

distance of the target from the ultrasonic sensor. If desired, the cycle can now be repeated by returning INIT to a low logic

level and then taking it high when the next transmission is desired.