New Product: RP120 Series, 1.5-A LDO Linear Regulator with BIAS Pin Featuring Low Input Voltage and Low On-resistance For Use in Consumer and Industrial Applications
- Achieving High Output Current, High PSRR, and Fast Response in Well Balance -

Nov. 18, 2021
Ricoh Electronic Devices Co., Ltd.

Ricoh Electronics has launched the RP120 series, a 1.5-A LDO linear regulator with a BIAS pin that features low on-resistance, suitable for use in consumer and industrial applications.

These days, as the advancement of electronic products proceeds, many of ICs used inside those products come to be driven by low-voltage and high-current power supply.

The decrease in the voltage of whole systems leads to the decrease in the margin of operating voltage, which causes problems such as deteriorating the signal-to-noise ratio of sensing devices when noise is imposed on the power supply. This means that power supply becomes more noise-sensitive and power management ICs are required to feature high ripple rejection (PSRR).

Also, in applications mentioned above, high peak current and voltage decrease caused by wire resistance are taken into consideration. This calls for small power management ICs to put just in the vicinity of the load IC instead of making the power supply centralized.

The RP120 series is an LDO linear regulator having two input pins: the power supply pin for the internal circuit (VBIAS) and the input pin of the internal NMOS driver (VIN). Thanks to this feature, it has a low on-resistance NMOS driver to achieve low-loss regulation.

The RP120 series can not only operate at low input voltage with low heat loss thanks to the low on-resistance feature, but also supply 1.5-A current despite its ultra-small WLCSP package (1.2 × 0.8 × 0.29 mm).

As the PSRR characteristic against ripples in VIN is as high as 95 dB (f = 1 kHz), the new LDO linear regulator can be used as a post-filter of a switching power supply even in environments sensitive to switching noise.

In addition, the built-in soft start function eases the measures against inrush current even in cases where a large output capacitor is used to reduce output noise.

The input VBIAS voltage range is from 2.4 V to 5.5 V with a maximum rating of 6.5 V. On output voltage range, the RP120 series has two variations: the externally settable type and the internally fixed type. The output voltage range of the former is adjustable in the range of 0.6 V to 3.6 V with an external resistor. The internally fixed type is still under development and is going to have an internally fixed output voltage range of 0.6 V to 2.0 V in 0.1 V step.

The RP120 series is an optimal power management IC for use in the following applications:

• Portable communication devices, battery-powered devices, cameras, video cameras, and audios
• Communication devices such as RF modules, and clock generators such as VCOs and PLLs
• Constant voltage source of FPGAs and SoCs, etc.

The RP120 series is manufactured at our Yashiro Plant (Kato City, Hyogo). It is scheduled to be applicable for our Product Longevity Program, maintaining state of supply for 10 years, which leads to relieve customer’s concern on the end of life of products.

RP120 Series (WLCSP-6-P11)

Key Features of RP120 Series

1. Low On-resistance and Low Input Voltage (From 0.6V+VDIFF) Achieved by Adding BIAS Pin

The RP120 series achieves low on-resistance and low input voltage operation by separating the power supply input pin (VIN pin) and the driver input pin (VBIAS pin). This enables the IC to output maximum 1.5 A despite its ultra-small WLCSP package. Also, even when the RP120 series outputs a very low voltage below 1 V, it can supply high current because it operates by the applied voltage based on the set output voltage and reduces heat loss.

2. Ultra-small WLCSP Package Enabling Small Mounting Area

The RP120 series adopts a WLCSP package (1.2 × 0.8 × 0.29 (mm)), which contributes to small mounting area. Besides, 0.6 × 0.3 mm size capacitors are available for CIN and CBIAS, and 1.0 × 0.5 mm size capacitors for COUT. This helps further reduce the mounting area.

3. High Output Current, High PSRR, and Fast Response

Clean power supply is necessary for CMOS image sensors and audio devices to provide good performance. The RP120 series achieves high output current of 1.5-A, fast response, and high PSRR in well balance.

4. Soft Start Function Suppressing Inrush Current

The RP120 series has a built-in soft start function to make the output voltage slew rate increase gradually and suppress inrush current at startup. The function is helpful for applications which prohibit steep startup. Also, the IC regulates its output by current (Typ. 600 mA) instead of by voltage when output capacitance is large. During the current limit operation, the output voltage waveform maintains constant inclination because the current is regulated at the same level until the output voltage reaches the set voltage. This enables inrush current suppression and safe startup of subsequent devices. In this case, the RP120 starts up more gradually than is controlled by the built-in soft start function.

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