AN10907
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© NXP B.V. 2010. All rights reserved.
Application note
Rev. 1 — 28 December 2010
53 of 82
NXP Semiconductors
AN10907
TEA1613T resonant power supply control IC
The amount of compensation needed to obtain a more constant performance, can be
determined during a few practical trials. This should give an indication of the target for the
total impedance of the divider.
Example:
Nominal SNSBOOST voltage is 2.5 V with I
cmp
= 1
A.
The required burst frequency f
HB(burst)
= 90 kHz which corresponds to SNSFB = 5.4 V.
Best compensation performance found with R
BURST1
is approximately 91 k
.
(25)
(26)
R
BURST2
= 176 k
To obtain a better overview of the relationship between SNSBOOST and SNSBURST,
regarding the compensation design, the calculation sheet can used. The sheet provides
more details and the possibility to visualize the result of value variation.
In the calculation sheet, an indicator is calculated on the amount of boost compensation
that is obtained for a certain situation. The indicator gives the change in
burst frequency preset (above which frequency level, the regulation enters burst mode)
due to the change in boost voltage.
For the given example this indicator amounts to: 72 Hz/V
9.5.3 Advanced design of SNSBURST circuit using a series resistor
V
SNSFB
3.5
V
R
BURST1
I
cmp
R
BURST1
3.5
V
R
BURST2
---------------------
+
+
5.4
V
=
=
R
BURST1
1
A
3.5
V
R
BURST2
---------------------
+
1.9
V
=
Fig 41. Designing the burst mode level using a series resistor
019aaa358
3.2 V
8 V
1.5
k
Ω
SNSFB
SNSBURST
RBURST1
RBURST2
RSBURST
TEA1613
CONTROL
HOLDHBC
3.5 V
0.1 V
compensation of burst
voltage level by boost voltage
SNSBOOST
SPIKE
FILTER
4
1
1.7
SNSBOOST [V]
I
cmp
[
μ
A]
2.5
