BD9302FP-E Datasheet, PDF (7/17 Pages) Rohm – A wide input voltage range of 6 V to 18 V, Easy switching frequency setting in the range of 200 k to 2.5 MHz.

33pF
30 30
kΩ kΩ
100kΩ
PGND1 ₁
3300
pF COMP1
2
20kΩ
0.6V
FB1 ₃
+ ERR
-
22kΩ
51kΩ
RT ₄
N.C. 5
SS1/SDWN ₆
0.1μF
VCC ₇
VCC
VREF
SS2/SDWN ₈
slope
+-
PWM
Internal
Bias
OSC
0.1μF
N.C. 9
0.6V
FB2 ₁₀
+
-
33
pF
COMP2 ₁₁
3300 ²⁰
pF ^kΩ
GND
12
ERR
PWM
+-
slope
13 ^PGND2
OCP
DRV2 _SDWN
Set
DRV1
Reset
SDWN
Current
Sense
25 ^SW1L
24 ^SW1
23 ^SW1
0.1μF
22 ^BOOT1
21 ^PVCC
10
μH
VO : 3.3V
10μF
UVLO
TSD
5V
20 ^PVCC
10
μF
19 ^PVCC
VCC
SDWN
Set
Reset ^DRV1
DRV2 ^SDWN
OCP
Current
Sense
18 ^PVCC
17 ^BOOT2
16 ^SW2
0.1
μF ¹⁰
μH
10
μF
SW2
15
VO : 1.2V
14 ^SW2L
Fig.19 Typical application circuit
ü Error amplifier (ERR) block
The ERR block is a circuit used to compare between the 0.6-V reference voltage and the feedback voltage of output
voltage. The COMP voltage, a result of this comparison, determines the switching Duty. Furthermore, soft start function is
activated with the SS voltage while in startup operation. Consequently, the COMP voltage is limited to the SS voltage.
ü Oscillator (OSC) block
The OSC block is a block to determine the switching frequency through the RT pin, which is settable in the range of 100
kHz to 2500 kHz.
ü SLOPE block
The SLOPE block is a block to generate a triangular wave from the clock generated with the OSC and then to transmit the
triangular wave to the PWM comparator.
ü PWM block
The PWM block is used to make comparison between the output COMP voltage of the error amplifier block and the
triangular wave of the SLOPE block, thus determining the switching Duty. The switching duty is limited with the maximum
duty ratio, which is internally determined, and will not reach 100%.
ü Reference voltage (UREF) block
The UREF block is a block to generate a 2.9-V internal reference voltage.
ü Protection circuit (UVLO/TSD) block
The UVLO (Under Voltage Lock Out) circuit is used to shut down the circuit when the voltage falls below approximately 3.3
V, while the TSD (Thermal Shutdown) circuit is used to shut down the circuit at a temperature of 175˚C and reset it at a
temperature of 160˚C.
ü Overcurrent protection circuit (OCP)
This function is used to detect a current passing through the power transistor FET with the CURRENT SENSE and activate
the overcurrent protection when the current reaches approximately 4 A. If the overcurrent protection is activated, switching
will be turned OFF to discharge the SS pin capacitance.
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