TS4621ML Datasheet, PDF (27/40 Pages) STMicroelectronics – High-performance class-G stereo headphone amplifier

TS4621ML
Application information
4.3
4.3.1
External component selection
The TS4621ML requires few external passive components to operate correctly. Each
component is described in the following sections.
Step-down inductor selection (L1)
The TS4621ML needs one inductor for the internal step-down DC/DC converter. This
inductor must fit the following constraints:
● Typical value: 2.2 µH to 3.3 µH (3.3 µH is recommended)
● Maximum current in operating mode: 400 mA
● Minimum inductor value at maximum current: 1.5 µH
● Maximum inductor value at zero current: 4.3 µH
● DC resistance: from 50 mΩ up to 450 mΩ
Table 6 shows the part number that should be used according to the inductor value.
Table 6. Recommended inductor
Manufacturer
Part number
LQM21PN3R3NGRD
Murata
LQM2MPN3R3G0L
FDK
LQM2MPN2R2G0L
MIPSZ2012D3R3
MIPSZ2012D2R2
Value
3.3 µH
3.3 µH
2.2 µH
3.3 µH
2.2 µH
4.3.2
Step-down output capacitor selection (C_t)
For the internal DC/DC step-down converter, the TS4621ML needs one output capacitor.
The three criteria for selecting the output capacitor are the range value of the capacitor
including self tolerance, DC variation and the minimum ESR value, which is mandatory to
avoid oscillation of the converter. Therefore the following constraints must be observed.
● Typical capacitor value: 10 µF at DC = 0 V
● Maximum capacitor value: 12 µF at DC = 0 V
● Minimum capacitor value: 4.8 µF at DC = 2 V
● Voltage range across this capacitor: from 1.1 V to 2 V
● Minimum DC ESR value: 5 mΩ
A ceramic capacitor in a 0603-type package is also recommended because of its close
placement to the TS4621ML, which makes it easier to minimize parasitic inductance and
resistance that have a negative impact on the audio performance.
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