TDA8596 NXP Semiconductors, TDA8596 Datasheet - Page 18

• Manufacturer Part Number: TDA8596
• Description: The TDA8596 is a quad Bridge Tied Load (BTL) audio power amplifier with symmetricalinputs, made in BCDMOS technology
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8596_2
Product data sheet
7.13 DC load detection
7.14 AC load detection
When the DC load detection is enabled (IB1[D1] = 1), a DC offset is slowly applied at the
outputs of the amplifiers during the start-up sequence (see
load currents as a result of the applied offset are measured. Based on this measurement
the load impedance can be determined to differentiate between normal, line driver and no
load (see
When the amplifier is used in line driver mode and the external booster has an input
impedance between 100
DBx[D5:D4] = 10 independent of the selected gain setting (see
Table 5.
[1]
By reading the I
amplifier whether a speaker or an external booster is connected and initiate the proper
selection of the amplifier gain, i.e. 26 dB for normal mode or 16 dB for line driver mode.
Gain selection will occur without audible pop noise when the amplifier is in mute.
The DC load bit DBx[D4] is shared with the AC load detection. This implies that
only valid when AC load detection is disabled (IB1[D2] = 0). When the AC load detection is
enabled (IB1[D2] = 1) the bits DBx[D4] will show the result of the AC load detection. After
disabling the AC load detection data bit DBx[D4] will show the result of the DC load
measurement, which was stored during the AC load measurement.
When AC load detection is enabled (IB1[D2] = 1), AC coupled speakers (e.g. tweeters)
can be detected during the assembly process. The detection is performed by means of
applying an audible input sine wave (e.g. 19 kHz) to the inputs of the amplifier. The AC
current into the load is measured with a 460 mA peak current detector to detect the
presence of an AC load. In order to prevent spurious AC load detection (e.g. due to
amplifier on/off switching), the AC load detection bit will only be set when the peak current
threshold is triggered at least three times. Besides the 460 mA peak current threshold, a
secondary threshold level at 230 mA is present. In case this level is not triggered, a high
ohmic DC load (e.g. line driver) is assumed (also refer to
DC load bits
DBx[D5]
0
1
1
0
Fig 12. DC load detection levels
Only when IB1[D2] = 0.
Figure
DC load detection translation table
DETECTION
LEVEL
LOAD
2
I
C-bus bits the microprocessor can determine after the start-up of the
12).
2
C-bus controlled 4
Rev. 02 — 8 November 2007
and 800
DBx[D4]
0
0
1
1
NORMAL
(DC-coupled), the DC load bits will be set at
45 W power amplifier with symmetrical inputs
20
100
LINE DRIVER MODE
Figure
800
Figure 4
Load indication
normal load
line driver load
open load
not valid
Table
5 k
13).
OPEN-CIRCUIT
and
5).
TDA8596
© NXP B.V. 2007. All rights reserved.
Figure
001aad176
[1]
5) and the
Table 5
18 of 48
is