TDA7296S STMicroelectronics, TDA7296S Datasheet - Page 6

• Manufacturer Part Number: TDA7296S
• Description: IC AMP AUDIO 60W AB MULTIWATT15
• Manufacturer: STMicroelectronics
• Type: Class ABr

Specifications of TDA7296S

• Output Type: 1-Channel (Mono)
• Max Output Power X Channels @ Load: 60W x 1 @ 8 Ohm
• Voltage - Supply: ±10 V ~ 35 V
• Features: Depop, Mute, Short-Circuit and Thermal Protection, Standby
• Mounting Type: Through Hole
• Package / Case: Multiwatt-15 (Vertical, Bent and Staggered Leads)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

TDA7296S
INTRODUCTION
In consumer electronics, an increasing demand
has arisen for very high power monolithic audio
amplifiers able to match, with a low cost, the per-
formance obtained from the best discrete de-
signs.
The task of realizing this linear integrated circuit
in conventional bipolar technology is made ex-
tremely difficult by the occurence of 2nd break-
down phoenomenon. It limits the safe operating
area (SOA) of the power devices, and, as a con-
sequence, the maximum attainable output power,
especially in presence of highly reactive loads.
Moreover, full exploitation of the SOA translates
into a substantial increase in circuit and layout
complexity due to the need of sophisticated pro-
tection circuits.
To overcome these substantial drawbacks, the
use of power MOS devices, which are immune
from secondary breakdown is highly desirable.
1) Output Stage
The main design task in developping a power op-
erational amplifier, independently of the technol-
ogy used, is that of realization of the output stage.
The solution shown as a principle shematic by
Fig3 represents the DMOS unity - gain output
buffer of the TDA7296S.
This large-signal, high-power buffer must be ca-
pable of handling extremely high current and volt-
age levels while maintaining acceptably low har-
monic distortion and good behaviour over
frequency response; moreover, an accurate con-
trol of quiescent current is required.
Figure 3: Principle Schematic of a DMOS unity-gain buffer.
6/11
A local linearizing feedback, provided by differen-
tial amplifier A, is used to fullfil the above require-
ments, allowing a simple and effective quiescent
current setting.
Proper biasing of the power output transistors
alone is however not enough to guarantee the ab-
sence of crossover distortion.
While a linearization of the DC transfer charac-
teristic of the stage is obtained, the dynamic be-
haviour of the system must be taken into account.
A significant aid in keeping the distortion contrib-
uted by the final stage as low as possible is pro-
vided by the compensation scheme, which ex-
ploits the direct connection of the Miller capacitor
at the amplifier’s output to introduce a local AC
feedback path enclosing the output stage itself.
2) Protections
In designing a power IC, particular attention must
be reserved to the circuits devoted to protection
of the device from short circuit or overload condi-
tions.
Due to the absence of the 2nd breakdown phe-
nomenon, the SOA of the power DMOS transis-
tors is delimited only by a maximum dissipation
curve dependent on the duration of the applied
stimulus.
In order to fully exploit the capabilities of the
power transistors, the protection scheme imple-
mented in this device combines a conventional
SOA protection circuit with a novel local tempera-
ture sensing technique which " dynamically" con-
trols the maximum dissipation.
In addition to the overload protection described