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| TLD5045EJ_15 Datasheet, PDF (22/30 Pages) Infineon Technologies AG – 700mA High Integration - DC/DC Step-Down Converter | |||
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Infineon® LITIX⢠Power
TLD5045EJ
Application Information
8.2
Switching Frequency Determination
With the external RFREQ, CFREQ and RCOMP network, it is possible to adjust the switching frequency of the regulator.
To ensure a stable frequency over a broad range of input voltage VREC an external resistor RCOMP can be used.
The following setup applies for the table displayed in Figure 8-3: VREC=12V, VLED=7.2V, LSW=220µH, RSET=14kΩ.
1
VREC
FREQ 6
RCOMP
TLD5045
GND
7
RFREQ
CFREQ
Figure 8-2 Setting tOFF Time of Regulator with External RFREQ, CFREQ Network
Rcomp
255.8kΩ
115.8kΩ
69.7kΩ
46.8kΩ
72.8kΩ
52.7kΩ
Rfreq
17.1kΩ
7.7kΩ
4.6kΩ
3.1kΩ
4.9kΩ
3.5kΩ
Cfreq
220pF
220pF
220pF
220pF
100pF
100pF
fsw
50kHz
100kHz
150kHz
200kHz
250kHz
300kHz
toff
6.47μs
3.19μs
2.12μs
1.59μs
1.27μs
1.06μs
Figure 8-3 RFREQ, CFREQ versus fSW Table
Data Sheet
22
Revision 1.0
2015-05-28
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