TL851

SONAR RANGING CONTROL

SLSS004 – SEPTEMBER 1983 – REVISED MARCH 1988

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POST OFFICE BOX 655303

Ranging Modules Like the SN28827

Transducers

description

Instruments TL852 sonar ranging receiver integrated circuit.

The TL851 is designed for distance measurement from six inches to 35 feet. The device has an internal oscillator

that uses a low-cost external ceramic resonator. With a simple interface and a 420-kHz ceramic resonator, the

device will drive a 50-kHz electrostatic transducer.

The device cycle begins when Initiate (INIT) is taken to the high logic level. There must be at least 5 ms from

ceramic-resonator-controlled oscillator to stabilize. The device will transmit a burst of 16 pulses each time INIT

is taken high.

The oscillator output (OSC) is enabled by INIT. The oscillator frequency is the ceramic resonator frequency

divided by 8.5 for the first 16 cycles (during transmit) and then the oscillator frequency changes to the ceramic

resonator frequency divided by 4.5 for the remainder of the device cycle.

When used with an external 420-kHz ceramic resonator, the device internal blanking disables the receive input

(REC) for 3.8 ms after initiate to exclude false receive inputs that may be caused by transducer ringing. The

internal blanking feature also eliminates echos from objects closer than 1.3 feet from the transducer. If it is

necessary to detect objects closer than 1.3 feet, then the internal blanking may be shortened by taking the

blanking inhibit (BINH) high, enabling the receive input. The blanking input (BLNK) may be used to disable the

receive input and reset ECHO to a low logic level at any time during the device cycle for selective echo exclusion

or for a multiple-echo mode of operation.

The device provides a synchronous 4-bit gain control output (12 steps) designed to control the gain of the TL852

sonar ranging receiver integrated circuit. The digital gain control waveforms are shown in Figure 2 with the

nominal transition times from INIT listed in the Gain Control Output Table.

The threshold of the internal receive level detector is 1.2 V. The TL851 operates over a supply voltage range

of 4.5 V to 6.8 V and is characterized for operation from 0

°C to 40°C.

Copyright

© 1988, Texas Instruments Incorporated

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

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XMIT

GND

GCD

GCA

GCB

GCC

REC

BLNK

BINH

INIT

FILT

XTAL2

XTAL1

OSC

ECHO

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