Summary
The AK7844 is a stereo audio power amplifier with a power booster designed to drive a piezo-electric speaker. The device employs AKM’s original Class-D amp architecture enabling stable audio output without the need of specific parts to drive such a capacitive load as a piezo-electronic speaker.
The built-in power booster based on DCDC converter technology produces a power rail of 8.75V from low supply voltage of down to 2.7V, allowing to provide high power in such as a low supply voltage application as Li-ion battery operation with very minimal external components.
AK7844 is available in a 31-pin WLCSP of 3x3mm body, and ideal for portable audio applications requiring serious saving of part space and power consumption.

Features

1. Stereo Class-D amplifier
   - Piezo-Electric (Ceramic) speaker or some capacitive load driver
   - 5Vrms BTL output with built-in power Booster
   - Filter-free for output stage
   - Supply current with no-input: 16mA
   - Shutdown current: 1A
   - Selectable Gain: +10.9dB to +31.9dB, 3dB step
   - Short-circuit and thermal protection
2. Boost DCDC converter
   - Boost voltage: 8.75V (Power supply: 2.7V to 4.5V)
   - Power Supply Rejection ratio: 50dB
3. Input amplifier
   - Analogue signal input for single-ended
   - Selectable LPF cut-off frequency (4, 8, 16kHz)
   - Pop noise suppressor
4. Operational voltage and temperature
   - Power supply: 2.7V to 4.5V
   - Power supply for digital interface: 1.65V to 4.5V
   - Operational temperature: -30deg to +85deg
5. Package 31-pin WLCSP (3.0mm 3.0mm )