AD628

Rev. F | Page 18 of 20

+IN

–IN

G = +0.1

10k

Ω

A1

–IN

100k

Ω

5V

+IN

–IN

A2

OUT

AD628

100k

Ω

10k

Ω

OTHER

BATTERIES IN

CHARGING

CIRCUIT

CHARGING

CIRCUIT

+1.5V

BATTERY

10k

Ω

+IN

10k

Ω

0V TO 5V

TO ADC

Figure 34. Battery Voltage Monitor

FILTER CAPACITOR VALUES

filter. The capacitor value is

()

μF

15.9/

t

f

C =

Table 7 shows several frequencies and their closest standard

capacitor values.

Table 7. Capacitor Values for Various Filter Frequencies

Frequency (Hz)

Capacitor Value (μF)

10

1.5

50

0.33

60

0.27

100

0.15

400

0.039

1 k

0.015

5 k

0.0033

10 k

0.0015

KELVIN CONNECTION

In certain applications, it may be desirable to connect the

inverting input of an amplifier to a remote reference point.

This eliminates errors resulting in circuit losses in interconnect-

ing wiring. The AD628 is particularly suited for this type of

connection. In Figure 35, a 10 kΩ resistor added in the feedback

matches the source impedance of A2. This is described in more

detail in the Gain Adjustment section.

+IN

–IN

A2

5V

–IN

+IN

OUT

CIRCUIT

LOSS

LOAD

+IN

–IN

G = +0.1

A1

AD628

10k

Ω

10k

Ω

10k

Ω

100k

Ω

100k

Ω

10k

Ω

Figure 35. Kelvin Connection