BQ2000_15 Datasheet, PDF (13/29 Pages) Texas Instruments – Programmable Multi-Chemistry Fast-Charge Management IC

bq2000
www.ti.com
SLUS138D – JANUARY 2008 – REVISED DECEMBER 2009
voltage and/or inductor value or decreasing C_HYS and/or the R_f × C_f filter corner frequency will increase the
switching frequency. Figure 10 and Figure 11 show empirical data on the variation in switching frequency based
on adjusting R_f and C_f. This data was taken with an input voltage of 12V, inductor value of 220 µH, R_SNS value of
50 mΩ, and C_HYS value of 4.7 pF. Typical switching frequencies for the bq2000 are between 100 and 200 kHz,
though it is possible to achieve switching frequencies in excess of 300kHz.
180
160
R_f = 748W
140
120
100
80
60
40
20
0
220 720 1220 1720 2220 2720 3220 3720 4220
C_f - pF
Figure 10. Switching Frequency vs Capacitance
210
190
C_f = 1000pF
170
150
130
110
90
70
50
200 300 400 500 600 700 800 900 1000 1100 1200
R_f - W
Figure 11. Switching Frequency vs Resistance
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