Product Features
The CM3702 offers the designer an integrated solution for providing clean power to audio circuits typically found in today's portable electronics devices. The CM3702 features a low noise regulator powered by an integrated charge pump enabling the generation of a separate, low noise 5V power source from a noisy 3 to 5V source.

Low Noise Regulator
The CM3702's regulator is designed to filter out noise from a digital supply, providing clean power for an audio subsystem, i.e. an audio codec. The regulator features low noise operation especially in the 20 to 20kHz audio band, which is suitable for a range of audio power applications. The regulator features overload current limiting, thermal shutdown protection and a CMOS design which results in low quiescent operating current, even at full load, making the CM3702 ideal for power-sensitive applications. A separate input (BYP) is provided for additional external filtering capacitance on the regulator reference voltage input, minimizing internal reference voltage noise and maximizing power supply ripple rejection.

Integrated Charge Pump
The CM3702 utilizes an integrated charge pump to provide 5V output at 200mA with an input voltage ranging from 3 to 5.5 volts. The charge pump maintains a nominal 0.8V differential between the LDO input and output which allows the device to exhibit good power supply ripple rejection while maintaining good power efficency. The charge pump operates with two external capacitors at approximately 250kHz, well above the audible frequency band. In addition, separate GND pins are provided for the charge pump independent of the rest of the circuitry to eliminate ground noise feed-through from the charge pump to the regulated output.

Separate Enable Inputs for Regulator and Charge Pump
The CM3702 features separate enable inputs for powering down the regulator and charge pump. Typically, for maximum power savings, both the regulator and the charge pump circuits are disabled during shutdown. For applications that require fast power supply power-up response, the charge pump circuit can be left enabled during shutdown, facilitating a much faster return to a full operating voltage level when the regulator is re-enabled.

Key Features and Benefits
The CM3702 offers the following features and benefits:

Industry’s first integrated, single-chip low noise regulator with integrated charge pump voltage booster 42dB (typ) PSRR in audio band 5V output with input voltage as low as 3.0V Charge pump output can also be used with an external regulator Up to 200mA continuous output current Low operating current (180µA typ) Low power shutdown modes Dual enable pins allow separate control of charge pump and LDO circuits for faster startup from sleep states Overload current limiting and over-temperature thermal shutdown for full protection Stable with low-ESR ceramic or tantalum capacitors Small, 10 pin, lead free MSOP package for space critical applications such as notebooks and PDAs.

Product Applications

Typical Application Circuit

A typical application circuit is shown above. Please note that in low cost applications, CIN and CBYP are not needed. The CM3702 is suitable for a number of applications where low-noise power supply operation as well as board space are major considerations. These include:

Notebook PCs Consumer Electronics PCMCIA cards White LED drivers 3V to 5V SIM cards Flash memory supplies Backup-battery boost converters

Sampling, Pricing and Availability
The lead-free CM3702 is currently sampling along with evaluation boards. The CM3702 is priced at $0.57 each in 10,000 unit quantities. Volume production is scheduled for this quarter.