Nisshinbo Micro Devices has released the NR1644 series, an LDO voltage regulator for use in consumer applications. In recent years, the demand for cameras in areas such as drones, medical devices, and security applications has increased. With this trend, the demand for CMOS image sensors (CIS) used in camera modules has also increased.
In order to achieve high image quality with low power consumption, there is a strong trend toward lower operating voltages in CIS. As a result, voltage regulators driving CIS are required to provide low output voltages and a stable power supply. In addition, since CIS is highly sensitive to noise, low-noise performance is also essential.
To solve these problems, the product is designed as an LDO voltage regulator with a high current of 2 A, while achieving a low output voltage of 0.4 V. The product is thus fully applicable to CIS, which uses higher current than before to improve image quality.
The product offers an ultra-low output noise voltage of 5 μVrms (10 Hz to 100 kHz) and a high ripple rejection of 50 dB (1 MHz) even under a heavy load of 1 A. Additionally, it has a built-in function to limit the start-up current to a constant value, which helps suppress inrush current and facilitates control even when the slew rate or ramp-up slope of the power supply input is constrained for downstream devices.
In general, a challenge in achieving low output voltages is that lowering the input voltage increases the on-resistance of the power transistor (PMOS output type), resulting in greater power loss. To achieve high-efficiency regulation, the product separates the power supply input pin for internal circuits (VBIAS) from the input pin for an NMOS power transistor (VIN). Furthermore, it incorporates the NMOS power transistor with a low on-resistance of 90 mΩ, allowing the dropout voltage to be kept as low as 180 mV (typ., IOUT = 2 A).
Two versions are available: a version that automatically switches between fast mode and low power mode based on the load current, reducing power consumption under light loads, and a fixed fast mode version that emphasizes responsiveness. The product also features a built-in discharge function that discharges the output capacitor when the device is turned off via the enable (EN) pin. It uses the DFN2020-8-GA (2.0 × 2.0 × 0.8 mm) package, which provides a good balance between mounting area and heat dissipation.
Features
- High Ripple Rejection and Low Output Noise Voltage Thanks to Noise Reduction Capacitor (CNR) : The product has a noise reduction (NR) pin. By connecting a noise reduction capacitor of 0.1 µF to 2.2 µF between the NR pin and the GND pin, high ripple rejection and low output noise voltage are achieved.
- Soft-start Function : When the product is turned on by a "high" level control signal applied to the EN pin, the soft-start time is determined by the capacitance of CNR connected to the NR pin and the constant current (1 mA) set internally.
Click here to learn more about the NR1644 Series.
