CS8190ENF16G Ver la hoja de datos (PDF) - ON Semiconductor

Número de pieza

componentes Descripción

Fabricante

CS8190ENF16G

Precision Air−Core Tach/Speedo Driver with Return to Zero

ON Semiconductor 

CS8190

VREG

R3

VC(t)

+

−

FREQIN

SQOUT

CCP

R4

+

QSQUARE

−

2.0 V

0.25 V

CP+

Q1

2.0 V

+

F/VOUT

CP−

Q3

−

RT

F to V

C4

Q2

Figure 7. Partial Schematic of Input and Charge Pump

VCC

tDCHG

T

tCHG

FREQIN 0

SQOUT

VREG

0

ICP+

VCP+

0

Figure 8. Timing Diagram of FREQIN and ICP

Ripple voltage on the F/V output causes pointer or needle

flutter especially at low input frequencies.

The response time of the F/V is determined by the time

constant formed by RT and C4. Increasing the value of C4

will reduce the ripple on the F/V output but will also increase

the response time. An increase in response time causes a

very slow meter movement and may be unacceptable for

many applications.

The CS8190 has an undervoltage detect circuit that disables

the input comparator when VCC falls below 8.0 V(typical).

With no input signal the F/V output voltage decreases and the

needle moves towards zero. A second undervoltage detect

circuit at 6.0 V(typical) causes the function generator to

generate a differential SIN drive voltage of zero volts and the

differential COS drive voltage to go as high as possible. This

combination of voltages (Figure 2) across the meter coil

moves the needle to the 0° position. Connecting a large

capacitor(> 2000 mF) to the VCC lead (C2 in Figure 9)

increases the time between these undervoltage points since

the capacitor discharges slowly and ensures that the needle

moves towards 0° as opposed to 360°. The exact value of the

capacitor depends on the response time of the system,the

maximum meter deflection and the current consumption of

the circuit. It should be selected by breadboarding the design

in the lab.

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