TPA3251D2 - 2 x 175W stereo 350W Mono class-D amplifier
- Differential analog inputs 2Vrms
- Efficiency 90% (4 ohms)
- 12-36V power supply
- 2 x 175 Watts into 4 Ohms BTL (10% THD)
- 2 x 220W into 3 ohms BTL (10% THD)
- 350W at 2 ohms PBTL (10% THD)
- 2 x 140W into 4 Ohms BTL (1% THD)
- 2 x 175W 3 ohms BTL (1% THD)
- 285W at 2 ohms PBTL (1% THD)
- Possible configurations are: Stereo (2 x BTL), Quad (4 x SE), Mono (PBTL), 2.1 Stereo Sub (2 x SE 1 x BTL)
- 100 kHz bandwidth
- 60dB PSRR, <60uV output noise, >111dB SNR
Update (05.08.2015): Rev 0.A PCBs are ordered at Elecrow
Update (30.08.2015): Rev 0.A Erstes Testmuster aufgebaut
Update (14.03.2016): “Shrink Mod” TPA3251D2 in 60x60mm
100 x 100 mm² should be possible, cooling might be challeging.
The fully differential inputs require an external driver, the TPA3251D2 itself has an internal gain of 20 DB.
Variant with a PNP differential amplifier
Variant with operational amplifiers
Based on data from Texas instruments.
Anti-Pop – Spannungsüberwachung
The following circuit is used to avoid noise when switching off the amplifier stage on the EVM. Depending on the used step down converter and power supply that works more or less well. Be observed can, that the "power monitor" must be set to a safe shutdown of noise-free bit "sharper". That through reduction of R31 (> = 33 k < 100 k) as well as parallel connection of a further Widerstandds to # 17. Unfortunately you bought a higher sensitivity to shocks of the supply voltage at higher levels in the event that the power supply can supply enough not "hard" it. In addition, temperature-induced effects arise.
Alternatively a circuit can be used, as shown below, - where to set the threshold on the related power supply and whose state of tension.
TPA3251D2 – Revision 0.A
TPA3251D2 – Shrink Mod
Reduction of the system on 60x60mm with active cooling and dual coils.
Heat sink temperature for 2x25W and 2x75W compared to the EVM by Texas instruments.
A significant improvement in results when using 8mm of spacers/standoffs under the Board.
The following measurements were carried out with 8 mm of spacers/standoffs under the Board.
System temperature at idle with a special focus on the Coilcraft MSs1210 inductors used.
The following chart gives the Coilcraft MSS1210 relative to the ambient temperature. Interesting here, the temperature decreases to central services (75W per channel).
The corresponding heat sink temperature is to:
Surface temperatures (idle) is summarized in a heatmap.