TDA3602 datasheet(13/26 Pages) PHILIPS

13 / 26 page

July 1994

Philips Semiconductors

Product speciﬁcation

Multiple output voltage regulator

TDA3602

APPLICATION INFORMATION

Noise

Table 3

Noise at regulator outputs dependent on

capacitive load (CL).

Note

1. Regulators loaded with 100mA; noise in

µV RMS

(B = 10 Hz to 1 MHz).

The available noise at the output of the regulators depends

on the bandwidth of the regulators, which can be adjusted

by means of the load capacitors. The noise figures are

given in Table 3.

Although stability is guarenteed when CL is higher than

µF (over temperature range) with tan (φ) = 1 in the

frequency range 1 kHz to 20 kHz, it is recommended to

use a 47

µF load capacitor for Regulators 1 and 2. When

a microprocessor is supplied by Regulator 3 much noise

can be produced by this microprocessor. This noise is not

influenced by increasing the load capacitor of Regulator 3.

The noise on the supply line depends on the supply

capacitor. When a high frequency capacitor of 220 nF with

an electrolytic capacitor of 100

µF in parallel is placed

directly over pin 1 (VP) and pin 6 (ground) the noise is

minimized.

The stabilizer is in 'power on' after the supply is

reconnected (Vbu> 7.9 V) and 0.1 < Vsc < 2.2 V.

Application circuits

STABILIZER WITHOUT MICROPROCESSOR 1

The low end application is illustrated in Fig.7. When switch

SW1 is closed, a pulse is generated at the state control

input by C5 and R1, and the regulator is switched from

power off to the on mode (all three regulators are on). The

HOLD signal can be used to control the mute signal for the

power amplifiers. This signal is HIGH when all the

regulators are in regulation and VP1 Schmitt trigger is true.

REGULATOR

(NOTE 1)

REG

µF47 µF

220

µF

150 mA

800

µV

220

µV

160

µV

100 mA

500

µV115 µV

50 mA

350

µV

190

µV

STABILIZER WITHOUT MICROPROCESSOR 2

Fig.8 illustrates the application circuit for a low end radio

set with push switches when no microprocessor is used.

The stabilizer can be switched to the on mode by pressing

switch SW1. In this mode, Regulators 1 and 2 are switched

on, so transistor T1 takes over from switch SW1. The

stabilizer can only be switched off by connecting the base

of T1 to ground (SW1 not pressed). This can be achieved

by pressing switch SW2.

The hold signal is only HIGH when the device is in the on

mode and both VP and the regulators are available, so that

this signal can be used to control the power stages (mute).

During a fault condition, this signal turns LOW

immediately.

When the stabilizer is connected to the supply for the first

time, the initial state will be the power-on stage, so

Regulators 1 and 2 are not switched on.

STABILIZER USED WITH MICROPROCESSOR

For a good understanding of the high end application,

shown in Fig.10, consult the flow chart of Fig.9.

When the set is off, a reset can be generated by

connecting the set to the supply for the first time (stabilizer

in power-on), or by pressing any key on the key matrix

(stabilizer in reset mode). When the reset is generated, the

stabilizer is held in the reset mode for a short period by T1.

The microprocessor has to take over control by making

reset mode equal to 0. The microprocessor can then

proceed with the initializing process. After this action, the

microprocessor has to check if the correct key has been

pressed. If so, the radio can be switched on by making on

equal to 0; if not, the microprocessor must switch the

device to the coma mode again, by making reset mode

and on both equal to 1; (wake mode is entered after a short

time constant, determined by R1

× C7 × constant), and

switch itself to sleep mode.

When the reset is generated for the first time (power-on

mode), the mode of the device can be detected by the hold

signal. If on = 0 and hold remains LOW, then the

microprocessor is in the power-on mode. In this event, the

microprocessor must go to the switch-off routine (making

on and reset mode both equal to 1).

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