TK10931VTL 데이터 시트보기 (PDF) - Toko America Inc

부품명

상세내역

제조사

TK10931VTL

NARROW BAND FM/AM IF SYSTEM

Toko America Inc  

TK10931V

CIRCUIT DESCRIPTION (CONT.)

(7) AM-ON/OFF Circuit

This IC provides an ON/OFF function for the AM block.

Because this was necessary for the stand-by state for the

AM block, it can be used as a power-save operation. The

input part equivalent circuit is shown in Figure 15.

By directly controlling the transisor-base as shown in the

equivalent circuit, the AM portion ON/OFF input control is

possible below a very small current of 50 µA. Regarding

Pin 14, the AM portion is in operation at 2 V and above; it

is in non-operation at 0.2 V and below. In non-operation,

the consumption current is down to approximately 2.4 mA.

The circuits that can be non-operational in AM OFF are

shown as follows.

Non-operation circuits:

AM IF circuit, AM IF-AGC circuit, AM detector circuit.

Always operating circuits:

RF-AGC output, Noise squelch circuit, Mixer circuit, Local

oscillator circuit, FM IF circuit, FM detector circuit.

Feedback through the power supply line from the cold side

of the phase shifter is common. To keep the signal level of

the phase shifter at its highest, treatment of its cold side is

very important.

Grounding the cold side with bypass a capacitor is impor-

tant. Adding a decoupling circuit that uses a CR or LC is

effective. An example is shown in Figure 16.

Avoid using high resistance values in the offset of the

multiplier in the FM detector. When using under about 1

kΩ, there is no effect because the inflow current in Pin 11

is under several µA.

3. When the signal is returned to the mixer from the

detector, the stability is at its worst. It is ideal that these

peripheral components are provided with different sides of

a double-sided board and that the reverse side is the GND

pattern.

47 µF

VCC

BI AS

50 k

AM

AM

ON

OFF

220 Ω

to 1 kΩ

0.1 µF

0.1 µF

FIGURE 15

(8) Attention to Pattern Layout

This product will provide stable operation. However, when

using this product, pay attention to the following (1-3) for

stable operation because the operating frequency is high.

Moreover, the standard application board of this product is

shown on page 25.

1. The VCC terminal capacitor is individually grounded by

the shortest distance to a GND terminal.

VCC Terminal (Pin 4) • GND Terminal (Pin 23)

2. Overall, the IF signal level is higher than other points.

Also, this point is the final stage in the limiter amplifier.

Therefore, this point easily provides positive feedback to

the first stage. Since feedback to the pre-stage depends

on radiation, use the shortest distance etch patterns pos-

sible.

January 2001 TOKO, Inc.

FIGURE 16: EXAMPLE OF STRONG DECOUPLING

AROUND THE PHASE SHIFTER

Page 23

Share Link: