TS2012EIJT datasheet(23/32 Pages) STMICROELECTRONICS

23 / 32 page

DocID026152 Rev 1

23/32

TS2012EI

Application information

4.5

Decoupling of the circuit

Power supply capacitors, referred to as CS1 and CS2, are needed to correctly bypass the

TS2012EI.

The TS2012EI has a typical switching frequency of 280 kHz and an output fall and rise time

of approximately 5 ns. Due to these very fast transients, careful decoupling is mandatory.

A 1 µF ceramic capacitor (CS1) between PVCC and PGND and one additional ceramic

capacitor 0.1 µF (CS2) are enough. A 1 µF capacitor must be located as close as possible to

the device PVCC pin in order to avoid any extra parasitic inductance or resistance created

by a long track wire. Parasitic loop inductance, in relation with di/dt, introduces overvoltage

that decreases the global efficiency of the device and may cause, if this parasitic inductance

is too high, a breakdown of the TS2012EI. For filtering low-frequency noise signals on the

power line, you can use a CS1 capacitor of 4.7 µF or more.

In addition, even if a ceramic capacitor has an adequate high frequency ESR (equivalent

series resistance) value, its current capability is also important. A size of 0603 is a good

compromise, particularly when a 4

 load is used.

Another important parameter is the rated voltage of the capacitor. A 1 µF/6.3 V capacitor

used at 5 V, loses about 50% of its value. With a power supply voltage of 5 V, the decoupling

value, instead of 1 µF, could be reduced to 0.5 µF. As CS has particular influence on the

THD+N in the medium-to-high frequency region, this capacitor variation becomes decisive.

In addition, less decoupling means higher overshoots, which can be problematic if they

reach the power supply AMR value (6 V).

4.6

Wake-up time (tWU) and shutdown time (tSTBY)

During the wake-up sequence when the standby is released to set the device ON, there is a

delay. The wake-up sequence of the TS2012EI consists of two phases. During the first

phase tWU-A, a digitally-generated delay, mutes the outputs. Then, the gain increasing

phase tWU-A begins. The gain increases smoothly from the mute state to the preset gain

selected by the digital pins G0 and G1. This startup sequence avoids any pop noise during

startup of the amplifier. Refer to Figure 37: Wake-up phase

TS2012EIJT 데이터시트(PDF) 23 Page - STMicroelectronics