TEA7530DP datasheet(6/11 Pages) STMICROELECTRONICS

6 / 11 page

Amplifier DC Supply

In transmission mode, the supply voltage is con-

trolled by the internal shunt DC regulator. For this

reason, the TEA7530 should be supplied from a

current source (see: supply considerations).

An antidistortion system is embodied which pro-

vides AGC control to avoid loudspeaker distortion

under current-limited conditions.

AGC Circuit action

When the supply VLS is insufficient, the voltage at

pin 8, falls below the reference voltage 1.2V, re-

sulting in transistor (TR) being switched off, re-

sulting zero current flow in resistor R. This state

enables the gain control system. Under these

conditions, the shunt DC supply will switch at a

rate determined by the time constant of the RC

network on pin 2.

This

switching

action

accomodates

normal

speech characteristic under low supply condi-

tions.

The AGC will be switched ON when the level on

Pin 2 is greater than a reference voltage of 0.4V.

Supply Considerations

a) Current MODE - Pin 8 is open (VLS =VLS1)or

connected to ground with an external resistor

(Rext) higher than 16K

Ω. The typical value of VLS

is :

VLS = 1.2V

40.5K

Ω+( 27K

Ω⁄ ⁄ REXT )

( 27KΩ ⁄⁄ REXT )

The AGC section is working as described in the

previous paragraph.

b) Voltage MODE - Pin 8 is shorted or connected

to GND with a resistor (REXT) lower than 16K

Ω.In

this condition the circuit must be supplied with a

DC voltage of 3 to 5.5V. In this case the AGC

section is permanently ON. Pin 2 must be shorted

to GND (in voltage mode only) to avoid perma-

nent attenuation of the signal at audio input

PIN FUNCTIONS

PIN 1: GND.

PIN 2: AUTOMATIC GAIN CONTROL FILTER

The antidistortion system response is adjusted by

the R-C network on this pin.

The AGC will be switched ON when the level on

pin 2 is greater than a reference voltage of 0.4V,

the RC-network charges (current source ON) or

discharges (current source OFF) according to

supply voltage.

Figure 11

TEA7530

6/11

TEA7530DP Datasheet(PDF) 6 Page - STMicroelectronics

TEA7530DP Datasheet(HTML) 6 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11

Datasheet Download

Link URL