NXP Semiconductors Product specification 3 W mono BTL audio amplifier with DC TDA7056AT volume control FUNCTIONAL DESCRIPTION The maximum gain of the amplifier is fixed at 35.5 dB. The DC volume control stage has a logarithmic control The TDA7056AT is a mono BTL output amplifier with DC characteristic. volume control. It is designed for use in TVs and monitors but is also suitable for battery-fed portable recorders and The total gain can be controlled from +35.5 to −44 dB. radios. If the DC volume control voltage is below 0.3 V, the device In conventional DC volume circuits the control or input switches to the mute mode. stage is AC-coupled to the output stage via external The amplifier is short-circuit proof to ground, V capacitors to keep the offset voltage low. In the P and across the load. A thermal protection circuit is also TDA7056AT the DC volume control stage is integrated into implemented. If the crystal temperature rises above the input stage so that no coupling capacitors are required. +150 °C the gain will be reduced, thereby reducing the With this configuration, a low offset voltage is still output power. Special attention is given to switch-on and maintained and the minimum supply voltage remains low. switch-off clicks, low HF radiation and a good overall The BTL principle offers the following advantages: stability. • Lower peak value of the supply current Power dissipation • The frequency of the ripple on the supply voltage is twice the signal frequency. Assume VP = 12 V; RL = 16 Ω. The maximum sine wave dissipation is 1.8 W. Consequently, a reduced power supply with smaller capacitors can be used which also results in cost The Rth vj-a of the package is 60 K/W. reductions. For portable applications there is a trend to Therefore Tamb(max) = 150 − 60 × 1.8 = 42 °C. decrease the supply voltage, resulting in a reduction of output power at conventional output stages. Using the BTL principle increases the output power. LIMITING VALUES In accordance with the Absolute Maximum Rating System (IEC 134). SYMBOLPARAMETERCONDITIONSMIN.MAX.UNIT VP supply voltage − 18 V V5, 7 input voltage pins 5 and 7 − 5 V IORM repetitive peak output current − 1.25 A IOSM non-repetitive peak output current − 1.5 A P < tot total power dissipation Tcase 60 °C − 1.5 W Tamb operating ambient temperature −40 +85 °C Tstg storage temperature −55 +150 °C Tvj virtual junction temperature − 150 °C tsc short-circuit time − 1 h THERMAL CHARACTERISTICSSYMBOLPARAMETERCONDITIONSVALUEUNIT Rth(j-a) thermal resistance from junction to ambient in free air 60 K/W 1998 Feb 23 5 Document Outline Features General description Quick reference data Ordering information Block diagram Pinning Functional description Power dissipation Limiting values Thermal characteristics Characteristics Test and application information Test conditions Voltage gain Output power Switch-on/switch-off Thermal behaviour: Short-circuit protection: Package outline Soldering Introduction Reflow soldering Wave soldering Repairing soldered joints Data sheet status Disclaimers
