DA7202 Datasheet, PDF (23/25 Pages) Dialog Semiconductor – 10 W Mono Class-D Amplifier for 2S Battery Devices

DA7202
10 W Mono Class-D Amplifier for 2S Battery Devices
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bias conditions. X5R or X7R dielectrics with a voltage rating of greater than 16 V are recommended
for best performance. Y5V and Z5U dielectrics are not recommended.
The voltage stability of a capacitor is strongly influenced by the capacitor size and its voltage rating.
In general, a capacitor in a larger package or with a higher voltage rating exhibits better stability. The
temperature variation of the X5R dielectric is about 15% over the −40°C to +85°C operating
temperature range of the DA7202, and is not a function of package or voltage rating.
Figure 21: Performance plot of the sample capacitor used in the example (below)
Use the following equation to determine the worst case capacitance, accounting for capacitor
variation over temperature, component tolerance, and voltage.
Where:
C_OUT = C_EFF × (1 − TEMPCO) × (1 − TOL)
● C_EFF is the effective capacitance at the operating voltage
● TEMPCO is the worst-case capacitor temperature coefficient, specified as a value between 0 and
1.
● TOL is the worst-case component tolerance, specified as a value between 0 and 1.
In this example, the worst case temperature coefficient (TEMPCO) over −40°C to +85°C is assumed
to be 15% for an X5R dielectric. The tolerance of the capacitor (TOL) is assumed to be 10%, and
CEFF is 4.620 μF at 7.2 V, as shown in Figure 21. Substituting these values into the equation yields
C_OUT = 4.620 μF × (1 − 0.15) × (1 − 0.1) = 3.53 μF
The capacitor chosen in this example therefore meets the minimum capacitance requirement of the
LDO over temperature and tolerance at the chosen output voltage.
To guarantee the performance of the DA7202, it is imperative that the effects of DC bias and
temperature on the behaviour of the capacitors are evaluated for each application.
Datasheet
CFR0011-120-00 Rev 5
Revision 3a
23 of 25
20-Aug-2015
© 2015 Dialog Semiconductor