Ricoh Europe (Netherlands) B.V. Semiconductor Support Centre has launched a new PWM/VFM Step-down DC/DC Converter RP509 with Synchronous Rectifier and an optional output current limit of 0.5A or 1A. This product offers a small footprint on the circuit board and requires small external components due to its high operating frequency of 6MHz.
The RP509 is one of the world’s most compact Step-down DC/DC Converter solutions with a package occupying only 1.12mm2 of circuit board space. This contributes to the product efficiency when used on high density and small circuit boards in portable gadget applications, such as smartphones, smart/fitness watches, tablets, wearable devices and communication modules. Other factors contributing to circuit board space reduction are the high operating frequency of 6.0MHz (resulting in the use of a small sized inductor of 0.47µH), an embedded driver transistor and synchronous rectification, which eliminates the need of an external diode.
The RP509 has two operating modes, selected by a mode pin:
- Forced PWM operating mode; the DC/DC converter switches at a fixed frequency rate, which has a lower output noise versus VFM operating mode.
- PWM/VFM auto switching mode; the DC/DC Converter switches between PWM and VFM mode automatically, resulting in the best efficiency level at either low or high output current demand.
Step-down DC/DC Converters need to function in a similar way to LDOs, providing power to advanced processors resulting in a load with fast transients. Portable gadget applications are able to operate in versatile modes, each with specific load characteristics.
In terms of circuit protection, various circuits are embedded to ensure a safe operation of the power supply. An under voltage lockout function (UVLO) disables the RP509 if the input voltage is below the threshold of the minimum operating voltage. An over-current limit circuit restricts the Lx peak current at each clock cycle; if the current exceeds the current limit it turns off the P-channel transistor. The over-current limit protects the DC/DC Converter and other electronic parts of the application from damage. One can select between versions with 0.5A or 1.0A current limit. The internal thermal shutdown circuit disables the RP509 as soon the junction temperature reaches 140°C and releases the protection circuit at 100°C.
The embedded soft-start function boots the internal circuits in 150µs. The output voltage version is fixed internally, which can be set in a range from 0.6V to 3.3V; the adjustable output voltage can be set from 0.6V to 5.5V with an external voltage divider. An optional auto-discharge function discharges the output capacitor quickly when the RP509 is disabled by the CE pin; an embedded transistor connected at the Vout pin is turned on and shorts the capacitor to ground.
Input Voltage Range 2.3V to 5.5V
Output Voltage Range (Fixed / Adjustable Output Voltage) 0.6V to 3.3V / 0.6V to 5.5V
Output Voltage Accuracy (Fixed Output Voltage) ±1.5% (Vset2 ≥ 1.2V), ±18mV (Vset < 1.2V)
Feedback Voltage Accuracy (Adjustable Output Voltage) ±9mV (Vfb = 0.6V)
Output Voltage/Feedback Voltage Temperature Coefficient ±100ppm/°C
Oscillator Frequency Typ. 6.0MHz
Oscillator Maximum Duty Min. 100%
Built-in Driver ON Resistance Typ. Pch. 175mΩ, Nch. 155mΩ(Vin = 3.6V)
Standby Current Typ. 0μA
UVLO Detector Threshold Typ. 2.0V
Soft-start Time Typ. 150µs
Inductor Current Limit Circuit (Optional) Typ. 1.0A / 1.6A
Package RP509Z (L1.28 x W0.88 x H0.64mm) WLCSP−6−P6
More information and the latest data sheet, see link below:
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