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TEA7063

SPEECH CIRCUIT WITH POWER MANAGEMENT

STMicroelectronics 

TEA7063

7. INTERNAL DESCRIPTION OF CURRENT

MANAGEMENT

7.1 Internal Power Supply Management

R9 fixes the line power supply management.

R9 fixes the values of: Iear, Iup, Iref and ILS.

A current line information is used to modifie the

values of Iear, Iup, Iref and ILS between a minimum

and a maximum values.

On Fig 10:

The transmit output stage is represented by a cur-

rent source (Itr). The Itr value depends of the DC

voltage on VLINE (pin 16) and RZAC value.

The other internal stages connected to VLINE (pin

16) are represented by a constant 1.3mA current

source.

7.2 DC Characteristics (internal)

The DC characteristic is equals to:

VLINE (pin 16) = VC (pin 17) + R6 • Iint

Iint is the sum of all the current sources con-

nected on VC (pin 17):

[Ip + Iref + Vpin17 / (r7 + r8)]

- Ip is the bias internal operational amplifiers

power supply.

- Iref = 1 / 3 • (Vrefi / R9); with Vrefi = 470mV

- Iref = 156 / R9 mA

The current line information changes Iint value;

at low line current (6mA): Iint = 4V / R9 + 60µA

at low line current (IL = ILb): Iint =8V / R9 + 60µA

7.3 Microcontroller Supply (internal)

Iup = [(p2 / r2) • Iref + 0.3] mA = [(p2 / r2) • 156 /

R9) + 0.3] mA

The current line information changes p2/r2 value;

at low line current (6mA): p2 / r2 = 70

at a line current (IL = ILb): p2 / r2 = 820

7.4 Earphone Current Supply (internal)

Iear = (p1 / r1) • Iref mA = (p1 / r1) • (156 / R9) mA

The current line information changes p1/r1 value;

at low line current (6mA): (p1 / r1) = 200

at a line current (IL = ILb): p1 / r1 = 2700

The maximum peak dynamic on the earphone is:

Vpear = Zear • Iear

7.5 Transmit Output Stage (internal)

The output stage bias current depends of the DC

voltage on pin 16 and on RZAC impedance.

0.1425

Itr =

•

VLINE

RZ

−

0.517

(RZ is the resistor

connected betwee pin3 and the ground)

7.6 Loudspeaker Current Source (internal)

The current source for external peripherals has

two slopes:

- First slope; before Iear, Iup, Itr and Iint are stabi-

lized at their maximum values: (IL = ILb)

ILS = 0.285 • IL

- Second slope; after Iear, Iup, Itr and Iint are sta-

bilized at their maximum values: (for IL > ILb)

∆ (ILS) = 0.91 • ∆(ILINE

Iear, Iup, Itr and Iint are stabilized at their maximum

values between 16 and 26mA, the absolute IL

value depends of R9 value. The line current (ILb)

where Iear, Iup, Itr, Iint are stabilized at their maxi-

mum values and where the slope of ILS change

is:

ILb = Iear

+

Iup

+ Itr +

0.715

Iint

+

1.3

7.7 Numerical Example

1) R9 = 100KΩ; R6 = 25KΩ

♦ DC characteristic = 6V for Iint max:

= 5V for Iint min:

Iint min (IL = 6mA) = 4 /100K + 60 = 100µA

Iint min (IL = ILb) = 8 /100K + 60 = 140µA

Vpin17 = 2.5V ⇒ R6 = 25KΩ ⇒

Vpin16 min (IL = 6mA) = 2.5 + 25 • 100E - 3 = 5V

Vpin16 max (IL = ILb) = 2.5 + 25 • 140E - 3 = 6V

♦ Current Sources

Iup min (IL = 6mA) = 0.4mA

Iup max (IL = ILb) = 1.6mA

Iear min (IL = 6mA) = 0.3mA

Iear max (IL = ILb) = 4.2mA

with RZ = 75Ω

Itr min (IL = 6mA) = 2.6mA

Itr max (IL = ILb) = 4.5mA

ILS min (IL = 6mA) = 1.3mA

♦ ILb

ILb =

1.6

+

4.2

+ 4.5 +

0.715

0.14

+

1.3 mA

ILb = 16.5mA

ILS (for IL = ILb) = 0.285 • ILb = 4.7mA

♦ at IL = 100mA:

∆(ILS) = 0.91 • ∆(IL) = 0.91 • (100 - 16.5) = 76mA

ILS = 4.7 + 76 = 80.7mA

2) R9 = 56KΩ; R6 = 18KΩ

♦ DC characteristic = 6.1V for Iint max:

♦ ∆Χ χηαραχτε = 4.8V for Iint min:

11/15

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