Data Sheet

TB67S279FTG, TB67S289FTG, TB67S249FTG Application Note
2018-03-07
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Preliminary
11.2. Internal oscillation frequency
OSCM oscillation frequency can be adjusted by changing the constant numbers of external
capacitor and resistor. In adjusting, it is recommended to change the resistor, while fixing the
capacitor to 270 pF.
Chopping frequency can be also changed by adjusting OSCM frequency. Please refer to below table
in adjusting the chopping frequency.
Product name: TB67S279FTG, TB67S289FTG, and TB67S249FTG
Board: Our company’s evaluation board
Power supply voltage: 24 V
COSC: 270 pF
Table 11.2 Relation of external resistor (ROSC) and internal oscillation frequency (f
OSCM
), chopping
frequency (f
chop
) (for reference only)
ROSC
f
OSCM
fchop
kΩ
MHz
kHz
1.5
2.63
164.38
1.8
2.37
148.13
2.0
2.23
139.38
2.2
2.08
130.00
2.7
1.80
112.50
3.0
1.67
104.38
3.3
1.55
96.88
3.9
1.34
83.75
4.7
1.15
71.88
5.1
1.07
66.88
5.6
0.98
61.25
6.8
0.83
51.88
8.2
0.70
43.75
10.0
0.58
36.25
Note: Values in above table are reference data. They are not guaranteed.
Setting chopping
frequency range
40 kΩ to 150 kHz
←
Typical value