RP504x Series

600mA PWM/VFM Step-Down DC/DC Converter with Synchronous Rectifier

Data Sheet / Flyer
Data Sheet * Flyer

The RP504x is a low supply current CMOS-based PWM/VFM step-down DC/DC converter with synchronous rectifier featuring 600mA*1 output current. Internally, a single converter consists of an oscillator, a reference voltage unit, an error amplifier, a switching control circuit, a mode control circuit (RP504xxx1A/D), a soft-start circuit, a Latch-type protection circuit, an under voltage lockout (UVLO) circuit and switching transistors.

The RP504x is employing synchronous rectification for improving the efficiency of rectification by replacing diodes with built-in switching transistors. Using synchronous rectification not only increases circuit performance but also allows a design to reduce parts count.

Power controlling method can be selected from forced PWM control type or PWM/VFM auto switching control type by inputting a signal to the MODE pin. In low output current, forced PWM control switches at fixed frequency rate in order to reduce noise. Likewise, in low output current, PWM/VFM auto switching control automatically switches from PWM mode to VFM mode in order to achieve high efficiency.

Output voltage is internally fixed type which allows output voltages that range from 0.8 V to 3.3 V in 0.1 V step.

The output voltage accuracy is as high as ±1.5% or ±18mV.
Protection circuits included in the RP504x are overcurrent protection circuit and latch type protection circuit.

Overcurrent protection circuit supervises the inductor peak current in each switching cycle, and if the current exceeds the LX current limit (ILXLIM), it turns off P-channel Tr. Latch type protection circuit latches the built-in driver to the OFF state and stops the operation of the step-down DC/DC converter if the overcurrent status continues or VOUT continues being the half of the setting voltage for equal or longer than protection delay time (tprot). To cancel the latch type protection circuit, select the standby mode or the active mode with the CE pin, or drop the power supply voltage below the UVLO detector threshold.

The RP504x is offered in 6-pin DFN(PLP)1216-6F, 6-pin DFN1616-6B and 5-pin SOT-23-5 packages which achieve the smallest possible footprint solution on boards where area is limited.

  • *)This is an approximate value. The output current is dependent on conditions and external components.
Supply Current Typ. 25µA in VFM mode without any load
Standby Current Max. 5µA
Input Voltage Range 2.3V to 5.5V (VOUT≥1.0V)
Output Voltage Range 0.8V to 3.3V in 0.1 V step
Output Voltage Accuracy ±1.5% (VOUT≥1.2V), ±18mV (VOUT<1.2V)
Temperature-Drift Coefficient of Output Voltage Typ. ±40ppm/°C
Oscillator Frequency Typ. 2.25MHz
Oscillator Maximum Duty Cycle Min. 100%
Built-in Driver ON Resistance Typ. Pch. 0.34Ω, Nch. 0.43Ω (VIN = 3.6V)
UVLO Detector Threshold Typ. 2.0V
Soft Start Time Typ. 0.15ms
Lx Current Limit Typ. 900mA
Latch-type Protection Circuit Typ. 1.5ms
Auto-discharge Function Only for RP504xxxxD
Power Controlling Method forced PWM control or PWM/VFM auto switching control
MODE Pin*1 "H" : forced PWM control,
"L" : PWM/VFM auto switching control
Package*1 DFN1616-6B, DFN(PLP)1216-6F, SOT-23-5
  • *1 DFN(PLP)1216-6F, DFN1616-6B: forced PWM control by pulling MODE pin "H" or PWM/VFM auto switching control by pulling MODE pin "L"
    SOT-23-5: forced PWM control for RP504xxxxC and PWM/VFM auto switching control for RP504xxxxB
  • Power source for battery-powered equipment.
  • Power source for hand-held communication equipment, cameras, VCRs, camcorders.
  • Power source for HDD, portable equipment.

Data Sheet Flyer Design Guide
RP504x Series
RP504x Series RP504x Series
Package Info. Mark Info. Quality Assurance Data
SOT-23-5 RP504N Reliability
DFN1616-6B RP504L Reliability
DFN(PLP)1216-6F RP504K Reliability


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