AN2031 APPLICATION NOTE

2/12

that have an adjustment range from +48dB to -78dB in 0.5dB increments. In addition, the mat-

er volume is adjustable from 0dB to -127dB in 0.5dB steps.

Tone control registers boost or cut the treble and bass by +/-12dB, in 2dB steps.

EQ filters are IIR biquads configurable by programmable coefficients.

2.4 POWER OUTPUT

The power level signals are applied to passive two-pole low pass filter, and provide low distor-

tion audio power to the load. The output filter functions to prevent unwanted high frequency

switching signals from reaching the load. Filter designs for 2

Ω. Peak voltage on power pins

must not exceed 35V.

Snubber networks are employed to protect the output MOSFETs from inductive transients,

which can reach levels higher than the supply voltage.

Output snubber filter values are R18/C66 and R14/C53.

The other critical components for device reliability are C47, C51, C58, C63 (1uF) and C48,

C52, C59, C64 (100nF); these bypass capacitors from Vcc and power GND pins of STA508.

These capacitors must be X7R Ceramic or Tantalum SMD construction and must be located

as close as possible to the device pins.

The STA508 shuts down when it reaches 150°C.

2.5 JUMPERS CONNECTOR

The STA308-508//-EVB provides some jumpers to configure the board.

2.5.1 JUMPERS:

JP1: (INT-SEL-EXT): short on EXT-SEL to use different power supplies; short on INT-SEL to

use only one power supply;

JP2: (2.5A): short (with solder tin) if STA308 IC is solder on the board. If there is the STA308A

this jumper could be opened;

JP3: (2.5A): short (with solder tin) if STA308 IC is solder on the board. If there is the STA308A

this jumper could be opened;

JP4: short this jumper to use two different power supply;

JP5: (OPTIC- SPDIF -ELEC): short the central pin with ELEC pin to use Electric S/PDIF; short

the central pin with OPTIC pin to use the optical S/PDIF.

JP6: short (with solder tin) 3.3A and center if STA308A IC is solder on the board. If there is the

STA308A this jumper could be short on 3.3V and center

JP7: this pin must be open.

2.5.2 CONNECTORS:

J1: Logic supply (5V)

J2: Power Supply (10V to 35V)

J3: Male 20 pin connector for plug control board

J4: RCA connector electric S/PDIF

J5: Optical S/PDIF SHARP GP1F31R

J6: Connector for output load A