Fujitsu MB39A105 manual Setting the Output Voltage, Setting the Triangular Oscillation Frequency

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MB39A105

■SETTING THE OUTPUT VOLTAGE

•Output Voltage Setting Circuit

VO
R1		Error
		Error
1	−	Amp		0.5
1	−		VO (V) =		+ R2)

	+			(R1
−INE	+			R2
−INE	+
R2
	(0.5 V)
CSCP
2

■SETTING THE TRIANGULAR OSCILLATION FREQUENCY

The triangular oscillation frequency is determined by the timing resistor (RT) connected to the RT terminal (pin 7) .

Triangular oscillation frequency : fosc

fosc (kHz) =:

3750

RT (kΩ)

12

Image 12

Contents Features DescriptionPackage PIN Assignment Pin No Symbol Descriptions PIN DescriptionBlock Diagram Parameter Symbol Condition Rating Unit Min Max Parameter Symbol Condition Value Unit Min TypAbsolute Maximum Ratings Recommended Operating ConditionsElectrical Characteristics ParameterPin Conditions Value Unit Min Typ Max Typical Characteristics ErrorTriangularwave oscillation Power Dissipation vs. Ambient Temperature Error amplifier block Error Amp1, Error Amp2 FunctionsTriangular-wave oscillator block OSC PWM comparator block PWM CompPower Timer-latch short-circuit protection circuit SCPUnder voltage lockout protection circuit Uvlo Short-circuit protection detection output functionSetting the Output Voltage Setting the Triangular Oscillation FrequencySetting the SOFT-START Times Timer-latch short-circuit protection circuit MB39A105 Equivalent Circuit Application Parts List Parts NoSelection of Components 2I OV O 2LV O Peak-to-peak value ESR Reference Data Usage Precaution Ordering InformationDo not apply negative voltages Part number Package RemarksPackage Dimension IndexFujitsu Limited