Electronic Components Datasheet Search |
|
BD9300F Datasheet(PDF) 8 Page - Rohm |
|
BD9300F Datasheet(HTML) 8 Page - Rohm |
8 / 17 page External component setting procedure Connecting a resistor and capacitor to the RT pin (pin 2) and the CT pin (pin 3) will set the triangular wave oscillation frequency. The RT determines the charge/discharge current to the capacitor. Referring to Fig. 18, set RT resistor and the CT capacitor. Recommended setting ranges are 5 to 100 kΩ for the CT resistor, 33 to 1000 pF for the CT capacitor, and 20 kHz to 800 kHz for the oscillation frequency. Any setting outside of these ranges may turn OFF switching, thus impairing the operation guarantee. (3) Setting of DTC voltage Applying the VDTC voltage to the DTC pin (pin 1) will fix the maximum duty ratio.This will serve to prevent the power transistor (FET) from being FULL ON. Fig. 19 shows the relationship between the DTC voltage and the maximum duty ratio. Referring to this Figure, set the DTC voltage.Next, generate the VDTC by dividing the VREF voltage with resistance and then input the VDTC in the DTC pin. Furthermore, the maximum duty ratio should be designed so as not to become a maximum duty for the normal use. The following section shows ranges for the normal use. VOMAX VCCMIN . Step-down voltage ONDutyMAX = 10000 1000 100 10 1 2 10 100 200 RT [kΩ] Fig. 18 RT/CT vs. Frequency Ta=25˚C Vcc=12V CT=33pF CT=33pF CT=100pF CT=100pF CT=200pF CT=200pF CT=470pF CT=470pF CT=1000pF CT=1000pF CT=33pF CT=100pF CT=200pF CT=470pF CT=1000pF 120 100 80 60 40 20 0 -20 1.4 1.5 2 1.9 1.8 1.7 1.6 VDTC [V] Fig. 19 DTC voltage vs. Maximum duty Ta=25˚C Vcc=12V Fosc=220kHz Fig. 15 Step-down voltage Fig.16 Step-up voltage Fig. 17 Inverting voltage R8+R9 R9 Vo = X 1.25 [V] R8+R9 R9 Vo = X 1.25 [V] R8 R9 ( ) Vo = 1.25 1– [V ] 8/16 12 14 Vo R8 R9 ERR + – . Step-down voltage . Step-up voltage . Inverting voltage Reference voltage: 1.25 V 12 14 Vo R8 R9 ERR + – Reference voltage: 1.25 V 12 14 11 Vo (Negative) R8 R9 ERR + – Reference voltage: 1.25 V VREF (1) Design of feedback resistance constant (2) Setting of oscillation frequency Set step-down, step-up, and inverting feedback resistance as shown below. Set resistance in the range of 1 kΩ to 330 kΩ. Setting the resistance to 1 kΩ or less will result in degraded power efficiency, while setting it to 330 kΩ or more will increase the offset voltage due to the input bias current of 0.1μA (TYP) of the error amplifier. VOMAX – VOMIN VOMAX . Step-up voltage ONDutyMAX = VOMAX VOMAX – VCCMIN . nverting voltage ONDutyMAX = |
Similar Part No. - BD9300F_08 |
|
Similar Description - BD9300F_08 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |