Application Information
OUTPUT VOLTAGE SELECTION FOR ADJUSTABLE
(LM3674-ADJ)
The output voltage of the adjustable parts can be programmed
through the resistor network connected from VOUT
to FB the to GND. VOUT will be adjusted to make FB equal to
0.5V. The resistor from FB to GND (R2) should be 200 kΩ to
keep the current drawn through this network small but large
enough that it is not susceptible to noise. If R2 is 200KΩ, and
given the VFB is 0.5V, then the current through the resistor
feedback network will be 2.5µA. The output voltage formula
is: Vout=vfb*(R1/R2+1)
Adjustable LM3674 Configurations for Various VOUT
VOUT (V) R1 (KΩ) R2(KΩ) C1 (pF) C2 (pF) L (µH) CIN (µF) COUT (µF)
1.0 200 200 18 None 2.2 4.7 10
1.1 191 158 18 None 2.2 4.7 10
1.2 280 200 12 None 2.2 4.7 10
1.5 357 178 10 None 2.2 4.7 10
1.6 442 200 8.2 None 2.2 4.7 10
1.7 432 178 8.2 None 2.2 4.7 10
1.8 464 178 8.2 None 2.2 4.7 10
1.875 523 191 6.8 None 2.2 4.7 10
2.5 402 100 8.2 None 2.2 4.7 10
2.8 464 100 8.2 33 2.2 4.7 10
3.3 562 100 6.8 33 2.2 4.7 10
按DATASHEET上第二個應用電路接,C2一定要加上,几十P即可,如果還有不明白請EMAIL:nick_zhou@aecotech.com 大傳電子:周工
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