L4620 查看數據表（PDF） - STMicroelectronics

零件编号

产品描述 (功能)

比赛名单

L4620

LIQUID LEVEL ALARM

STMicroelectronics 

L4620

PIN FUNCTION (Block Diagram)

N°

Name

Function

1 Oscillator

A capacitor Cosc connected to ground and a resistor Rosc connected to pin 5 (supply

voltage) set the frequency of the internal oscillator. The period is given by: Tosc = 0.693

(Rosc + 5000) Cosc

2 Sensor Output A squarewave is available at this pin to drive the external sensor. The output

frequency is 1/32 of the internal oscillator fosc, i.e. 50Hz using the values of

Rosc = 180kΩ and Cosc = 4.7nF for the external components.

3 Sensor Input Connection for liquid level sensing. During the zero level of the squarewave signal at

pin 2, the internal sensing circuit is disabled. During the high level of the wave shape

the input is compared with a threshold which depends on the output sensor volta

VSENSH = 0.4V2 (typ). If the input voltage becomes higher than the above VSENSH, the

Vsens value is reduced to VSENSL = 0.22V2 (typ), providing an hysteresis available with

both the programmable polarities.

4 GND

This pin must be connected to ground.

5 Supply Voltage Supply voltage input. A 4.5V (typical) zener is present at the input. The external

resistor limits the current through the zener for high supply voltages. Moreover when

the voltage at this pin is down 2.5V (typical) the internal reset circuit is activated

6 Alarm Driver An internal open collector stage is available at this pin to drive the external alarm

Output

indicator by a rectangular waveshape. The output period depends on the external

component Rosc and Cosc. Using the recommended values of block diagram th

7 Alarm Delay

Select

This program pin selects the alarm delay to activate the output stage after a low liquid

level indication of the sensor. The delay depends on the internal oscillator frequency.

Refer to application circuit, if this pin is kept low the typical delay is 10.

8 Sensor Polarity Through this pin it is possible to program both the sensor polarity with respect to the

Select Output internal threshold and the duty-cycle of the output waveform which drives the alarm.

Duty-cycle

When this pin is kept low the output rectangular wave duty cycle is 1:64

Select

(T = 320ms, t = 5ms in fig. 2) and the output is activated, after the delay time, if the

voltage at pin 3 is higher than VSENS. When the voltage at this pin is high the output

duty cycle is 50% (t = 160ms) and the output goes on, after the delay

3/9

Share Link: