STA540 STMicroelectronics, STA540 Datasheet - Page 16

• Manufacturer Part Number: STA540
• Description: IC AMP AUD DUAL/QUAD MULTIWATT15
• Manufacturer: STMicroelectronics
• Type: Class ABr

Specifications of STA540

• Output Type: 2-Channel (Stereo) or 4-Channel (Quad)
• Max Output Power X Channels @ Load: 38W x 2 @ 4 Ohm; 16W x 4 @ 4 Ohm
• Voltage - Supply: 8 V ~ 22 V
• Features: Short-Circuit and Thermal Protection, Standby
• Mounting Type: Through Hole
• Package / Case: Multiwatt-15 (Vertical, Bent and Staggered Leads)
• Amplifier Class: AB
• No. Of Channels: 4
• Output Power: 24W
• Supply Voltage Range: 8V To 22V
• Thd + N: 0.02% @ 4W, 4ohm, VS=14.4V
• Load Impedance: 8ohm
• Operating Temperature Range: -40°C To +150°C
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-8880-5

Practical information
6.6
6.6.1
6.6.2
16/23
Output stage
The fully complementary output stage is possible with the power ICV PNP component.
This novel design is based on the connection shown in
exploitation of its capabilities. The clear advantages this new approach has over classical
output stages are described in the following sections.
Rail-to-rail output voltage swing without bootstrap capacitors
The output swing is limited only by the V
range of 0.3 Ω (R
Classical solutions adopting composite PNP-NPN for the upper output stage have higher
saturation loss on the top side of the waveform.
This unbalanced saturation causes a significant power reduction. The only way to recover
power includes of the addition of expensive bootstrap capacitors.
Absolute stability without external compensation
With reference to the circuit shown in
than unity, that is, approximately 1 + R2/R1. The DC output level (VCC / 2) is fixed by an
auxiliary amplifier common to all the channels.
By controlling the amount of this local feedback it is possible to force the loop gain (A*β) to
less than unity at frequency where the phase shift is 180°. This means that the output buffer
is intrinsically stable and not prone to oscillation.
The above feature has been achieved even though there is very low closed-loop gain of the
amplifier.
This contrasts with the classical PNP-NPN stage which makes use of external RC networks,
namely the Boucherot cells, for reducing the gain at high frequencies.
Figure 22. The new output stage
sat
) each.
Figure
CEsat
22, the low frequency gain V
of the output transistors, which are in the
Figure 22
and allows the full
out
/V
in
is greater
STA540