BD9221F Datasheet, PDF (3/5 Pages) Rohm – Silicon Monolithic Integrated Circuit

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〇Package Dimensions
MAX11.55 (include. BURR)
Device name
BD9221F
Lot No.
〇PIN No.・PIN NAME・FUNCTION
SOP-18 (Unit:mm)
BD9221F
No. PIN
Function
No. PIN
Function
1 VCC Supply voltage input
18 N1 NMOS FET driver
2 STB Stand-by switch
17 N2 NMOS FET driver
External resistor from SRT to RT for adjusting
3 SRT the triangle oscillator
16 PGND Ground for FET drivers
External resistor from SRT to RT for adjusting
4 RT the triangle oscillator
15 CLK_IN OUTPUT synchronous signal input pin
5 GND GROUND
14 PWM_IN Dimming pulse signal input pin
6 - Non Conection
13 SS External capacitor from SS to GND for Soft Start Control
7 FB Error amplifier output
12 CP External capacitor from CP to GND for Timer Latch
8 IS Error amplifier input
11 FAIL Error signal output pin
9 VS Error amplifier input
10 COMP Over voltage detect pin
○Setting of synchronous function
BD9221F output frequency with ＜CLK_IN Freq.＊1/2＞to N1 and N2 pin.
（signal amplitude level : H=over 2.4V ,L=under0.8V）
Set the IC frequency by adjusting RT resistor value, in order to satisfy under synchronous
condition.
F(IC)=F(CLK_IN)*1/2*A
F(IC)･･･IC Freq. F(CLK_IN)･･･Synchronous Freq. A･･･under 90%／over 75%
However this synchronous function is connected with SRT movement.
SRT=OFF(OPEN) : synchronous mode.
SRT=ON(LOW):IC Frequency mode.
REV. A