TA31275FN/ TA31275FNG

03-01-23

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12. Control Terminal for Quick Charge Circuit (CHARGE)

CHARGE (15 pin) is control terminal for quick charge circuit. REF (20 pin) control terminal for quick

charge a given period by time constant of internal resistance and outside capacitance. Enabling the

CHARGE pin requires an external capacitor. In normal operation, connect a capacitor having the same

capacitance as that of the capacitor connected to the REF pin (pin 20).

If the connected external capacitor (C11) is 0.1

µF, the quick charge time is 7 ms (typically).

13. Bit Rate Filter for FM

The current FM bit rate filter is used as a tertiary filter.

If the filter is to be used at a rate other than 1200 bps, please change the filter constant.

Quadratic Filter (NRZ)

R10

R9

R8

C20

C19

C18

1200 bps

68 k

Ω

68 k

Ω

68 k

Ω

0.01

µF

560 pF

3300 pF

2400 bps

68 k

Ω

68 k

Ω

68 k

Ω

4700 pF

270 pF

1500 pF

4800 bps

68 k

Ω

68 k

Ω

68 k

Ω

2200 pF

150 pF

680 pF

14. Bit Rate Filter for AM

The current AM bit rate filter is used as a quadratic filter.

If the filter is to be used at a rate other than 1200 bps, please change the filter constant.

Quadratic Filter (NRZ)

(the bit rate filter time constant takes into account the internal resistance RSSI (30 k

Ω))

R

R10

C20

C19

1200 bps

36 k

Ω

68 k

Ω

4700 pF

1500 pF

2400 bps

36 k

Ω

68 k

Ω

2200 pF

680 pF

4800 bps

36 k

Ω

68 k

Ω

1000 pF

390 pF

When the filter constants shown below are used, it is not necessary to set the R constant value.

R

R10

C20

C19

1200 bps



30 k

Ω

6800 pF

2200 pF

2400 bps



30 k

Ω

3300 pF

1500 pF

4800 bps



30 k

Ω

1800 pF

820 pF

In addition, the current AM bit rate filter can be used as a tertiary filter.

If the filter is to be used at a rate other than 1200 bps, please change the filter constant.