TA8220HQ 데이터 시트보기 (PDF) - Toshiba

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TA8220HQ

30W BTL × 2ch Audio Power Amplifier

Toshiba 

TA8220HQ

The total closed loop gain GV of this IC can be obtained by expression below when the closed loop voltage gain of

amp1 is GV1.

GV1

=

20log

R1

+ (Rf + R2

Rf + R2

)

(dB)LLL (1)

The closed loop voltage gain of power amp, amp3 and amp4 is fixed at GV3≒GV4 = 20dB.

Therefore, the total closed circuit voltage gain GV is obtained through BTL connection by the expression below.

GV = GV1 + GV3 + 6 (dB)………(2)

For example, when Rf = 0Ω, GV is obtained by the

expressions (1) and (2) as shown below.

GV≒24 + 20 + 6 = 50dB

The voltage gain is reduced when Rf is increased.

(Fig.2)

With the voltage gain reduced, since (1) the

oscillation stability is reduced, and (2) the pop noise

changes when VCC is set to on, refer to the items 3

and 4.

2. Stand−by SW function

By means of controlling (4)pin (stand−by terminal) to

high and low, the power supply can be set to on and off.

The threshold voltage of (4)pin is set at 2.1V (3VBE), and

the power supply current is about 1µA (typ.) at the

stand−by state.

Control voltage of (4)pin: V (SB)

Stand−By

Power

V (SB) (V)

On

Off

0~2

Off

On

3~VCC

<Adjustage of stand−by SW>

(1) Since VCC can directly be controlled to on / off by the microcomputer, the switching relay can be omitted.

(2) Since the control current is microscopic, the switching relay of small current capacity is satisfactory for

switching.

3

2006-04-28

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