tda8592j NXP Semiconductors, tda8592j Datasheet - Page 7

• Manufacturer Part Number: tda8592j
• Description: I?c-bus Controlled 4 X 50 W Power Amplifier
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 13007
Preliminary data sheet
7.10 Input and AC ground capacitor values
7.11 DC-load detection
7.12 I
7.13 AC-load detection
7.8 Speaker protection
7.9 Line driver mode
If one side of a speaker is connected to ground, a missing current protection is
implemented to prevent damage to the speaker. A fault condition is detected in a channel
when there is a mismatch between the power current in the high side and the power
current in the low side; during a fault condition the channel will be switched off.
The load status of each channel can be read via the I
the speaker connected to ground), short to V
and shorted load.
An amplifier can be used as a line driver by switching it to low gain mode. In normal mode,
the gain between single-ended input and differential output (across the load) is 26 dB. In
low gain mode the gain between single-ended input and differential output is 20 dB.
The negative inputs to all four amplifier channels are combined at pin ACGND. To obtain
the best performance for supply voltage ripple rejection and unwanted audible noise, the
value of the capacitor connected to pin ACGND must be as close as possible to 4 times
the value of the input capacitor connected to the positive input of each channel.
When DC-load detection is enabled, during the start-up cycle, a DC offset is applied
slowly to the amplifier outputs, and the output currents are measured. If the output current
of an amplifier rises above a certain level, it is assumed that there is a load of less than
6
detected.
Because the offset is measured during the amplifier start-up cycle, detection is inaudible
and can be performed every time the amplifier is switched on.
If in the application more amplifiers are used, the I
TDA8592Q can be changed with an external resistor: see
AC-load detection can be used to detect that AC-coupled speakers are connected
correctly during assembly. This requires at least 3 periods of a 19 kHz sine wave to be
applied to the amplifier inputs. The amplifier produces a peak output voltage which also
generates a peak output current through the AC-coupled speaker. The 19 kHz sine wave
is also audible during the test. If the amplifier detects three current peaks that are greater
than 550 mA, the AC-load detection bit D1 of instruction byte IB1 is set to logic 1. Three
current peaks are counted to avoid false AC-load detection which can occur if the input
signal is switched on and off. The peak current counter can be reset by setting bit D1 of
instruction byte IB1 to logic 0. To guarantee AC-load detection, an amplifier current of
more than 550 mA is required. AC-load detection will never occur with a current of less
2
C-bus address selection
and bit D5 is reset in the associated data byte register to indicate that a load is
Rev. 01 — 8 June 2004
TDA8592J; TDA8592Q
I
2
C-bus controlled 4
P
(one side of the speaker connected to V
2
C-bus address of the TDA8592J;
2
C-bus: short to ground (one side of
Section
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
8.
50 W power amplifier
7 of 33
P
),