TDA8596_15 Datasheet, PDF (7/48 Pages) NXP Semiconductors – I2C-bus controlled 4 ´ 45 W power amplifier with symmetrical inputs

NXP Semiconductors
TDA8596
I²C-bus controlled 4 × 45 W power amplifier with symmetrical inputs
7.4.1 SOAR protection
The output transistors are protected by a Safe Operating ARea (SOAR) protection. The
TDA8596 has a two-stage SOAR protection:
• If the differential output voltage across the load (V_o) is less than 1 V, and the current
through the load (I_L) exceeds 4 A, the amplifier channel will be switched off during
16 ms. To prevent spurious switch-off events (which may occur for instance in case of
inductive loads or very high input signals), the fault condition (V_o < 1 V and I_L > 4 A)
must exist for more than 300 µs.
• If the differential output voltage across the load (V_o) is more than 1 V, and the current
through the load (I_L) exceeds 8 A, the amplifier channel will be switched off during
16 ms.
7.4.2 Speaker protection
To prevent damage of the speaker when one side of the speaker is connected to ground, a
missing-current protection is implemented. When the current in the high side power
transistor of one amplifier channel is not equal to the current through the corresponding
low side power transistor, a fault condition is assumed and the concerning channel will be
switched off. The boundary conditions for the activation of this speaker protection are:
• V_o < 1.55 V and I_missing > 1 A for 80 µs
• V_o > 1.55 V and I_missing > 3 A for 80 µs
7.5 Standby and mute operation
The functionality of the STB pin depends on the mode of operation of the device (i.e.
legacy- or I²C-bus mode).
7.5.1 I²C-bus mode
When the STB pin is LOW (< 1 V), the device is in standby condition. The I²C-bus lines
will not be loaded and the quiescent current will be low. When the STB pin is switched
HIGH (> 2.5 V) the TDA8596 switches to operating condition and performs a Power-On
Reset (POR). This will cause the DIAG pin to be pulled LOW. The TDA8596 will start-up
when bit D0 of instruction byte IB1 is set. Bit D0 will also reset the ‘power-on reset
occurred’ bit (DB2[D7]) and releases the DIAG pin.
The soft- and fast-mute functions can be activated by means of I²C-bus instructions. The
soft mute can be activated independently for the front (1 and 3) and rear (2 and 4)
channels, and mutes the audio in 20 ms. The fast mute is activated for all channels
simultaneously and mutes the audio in 0.1 ms. Releasing the mute will always occur via a
soft mute and will take 20 ms.
When the STB pin is switched LOW and the amplifier is in Operating mode, the fast mute
will be activated prior to shut-down. This enables the option to fast mute the amplifier by
means of the STB pin in case of, for instance an engine start, thus preventing audible pop
noise.
7.5.2 Legacy mode (pin ADSEL connected to ground)
In legacy mode, the function of the STB pin changes into a three level (standby, mute and
operating) enable pin and the amplifier will directly start-up when the STB pin is put into
Mute or Normal operating mode. Mute operation is controlled through an internal timer
TDA8596_2
Product data sheet
Rev. 02 — 8 November 2007
© NXP B.V. 2007. All rights reserved.
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