TDA8588J Datasheet, PDF (11/54 Pages) NXP Semiconductors – I2C-bus controlled 4 x 50 Watt power amplifier and multiple voltage regulator

Philips Semiconductors
I²C-bus controlled 4 × 50 Watt power
amplifier and multiple voltage regulator
Product specification
TDA8588J; TDA8588xJ
VOLTAGE REGULATORS
The voltage regulator section contains:
• Four switchable regulators and one permanent active
regulator
• Two power switches with loss-of-ground protection
• Reset push-pull output
• Backup functionality.
The quiescent current condition has a very low current
level of 150 µA typical with only regulator 2 active. The
TDA8588 uses low dropout voltage regulators for use in
low voltage applications.
All of the voltage regulators except for the standby
regulator can be controlled via the I²C-bus. The voltage
regulator section of this device has two power switches
which are capable of delivering unregulated 400 mA
continuous current, and has several fail-safe protection
modes. It conforms to peak transient tests and protects
against continuous high voltage (24 V), short-circuits and
thermal stress. A reset warning signal is asserted if
regulator 2 is out of regulation. Regulator 2 will try to
maintain output for as long as possible even if a thermal
shut-down or any other fault condition occurs. During
overvoltage stress conditions, all outputs except
regulator 2 will switch off and the device will be able to
supply a minimum current for an indefinite amount of time
sufficient for powering the memory of a microcontroller.
Provision is made for an external reserve supply capacitor
to be connected to pin BUCAP which can store enough
energy to allow regulator 2 to supply a microcontroller for
a period long enough for it to prepare for a loss-of-voltage.
Backup capacitor
The backup capacitor is used as a backup supply for the
regulator 2 output when the battery supply voltage (V_P)
cannot support the regulator 2 voltage.
Backup function
The backup function is implemented by a switch function,
which behaves like an ideal diode between pins V_P
and BUCAP; the forward voltage of this ideal diode
depends on the current flowing through it. The backup
function supplies regulator 2 during brief periods when no
supply voltage is present on pin V_P. It requires an external
capacitor to be connected to pin BUCAP and ground.
When the supply voltage is present on pin V_P this
capacitor will be charged to a level of V_P − 0.3 V. When the
supply voltage is absent from pin V_P, this charge can then
be used to supply regulator 2 for a brief period (t_backup)
calculated using the formula:
t_backup
=
C_b
a
ck
up
×
R_L
×


V-----_P----–_-----(_{--V-V---O-O---(-(-R-R---EE---G-G---2-2--))---}–_{----0----.-5----})_{-}
Example: V_P = 14.4 V, V_O(REG2) = 5 V, R_L = 1 kΩ and
C_backup = 100 µF provides a t_backup of 177 ms.
When an overvoltage condition occurs, the voltage on
pin BUCAP is limited to approximately 24 V; see Fig.5.
Regulator 2
Regulator 2 is intended to supply the microcontroller and
has a low quiescent current. This supply cannot be shut
down in response to overvoltage stress conditions, and is
not I²C-bus controllable to prevent the microcontroller from
being damaged by overvoltage which could occur during a
disturbance of the I²C-bus. This supply will not shut down
during load dump transients or during a high
thermal-protection condition.
2004 Feb 24
11