CS289 datasheet(5/6 Pages) CHERRY

Part #	CS289

Description	20mA Air-Core Tachometer Drive Circuit

PDF	6 Pages

Scroll/Zoom	100%

Manufacturer	CHERRY [Cherry Semiconductor Corporation]

Direct Link	http://www.cherrycorp.com/

Logo

5 / 6 page

IIN

0.7V

2.1V

IOUT/EQ

10k

TRIM

VF/V

OUT = 2.1 + Frequency x CT x RT (VREG -0 .7)

The above equations were used in calculating the follow-

ing values, where VF/V

OUT = 7.1V at =270¡ and CT = 0.01 F.

4 cylinder: Freq = 200Hz, RT = 320k½

6 cylinder: Freq = 300Hz, RT = 220k½

8 cylinder: Freq = 400Hz, RT = 150k½

Tachometer Application

RPM

x # OF CYL.

= Frequency

Typical values shown above apply to a nominal value of

VREG of 8.5 volts. It must be realized that trimming of RT

will be necessary to compensate for variations in regula-

tor voltage from one unit to another.

An alternative to this adjustment is to replace R2 with a

potentiometer, as shown in Figure 2.

Partial schematic shown in Figure 3 represents one met-

hod for use with DC applications instead of frequency.

Figure 2: Alternate Trimming Method

Figure 3: DC Application

CS289 Datasheet(PDF) 5 Page - Cherry Semiconductor Corporation