Class D/1-Bit Audio Power Amplifier Output Stage

The AD1991 is a two-channel BTL or four-channel single-ended class-D audio power output stage. The AD1991 is arranged internally as four transistor pairs, which can be used as two H bridge outputs (Two-Channel Mode), or as four single ended outputs (Four-Channel Mode), using either two or four TTL compatible inputs to control the transistors. The output stage can be operated over a range of power supply voltage from 8 V to 20 V. A dead time is automatically provided between the switching of the high side transistor and low side transistor when the control inputs change level to ensure that both the high side transistor and low side transistor are never on at the same time. The part is configured during RESET to be in either two-channel mode or four-channel mode.

To protect the IC as well as the connected speakers, the AD1991 provides turn-on and turn-off pop suppression, short circuit protection and overtemperature shut down. To control the IC, a Power Down/Reset input plus a mute pin are available.

Pricing and Availability

The AD1991 Class D Output Stage is available in a 52-pin TQFP package and is rated for the industrial -40°C to +85°C temperature range. The AD1991 is in Production, and Samples are available. Prices begin at $7.91 in 1,000-piece quantities.