The RT9945 is a complete power management IC (PMIC) for handheld device platform. This PMIC contains a fully integrated linear charger for a single cell Lithium Ion battery, five LDO linear regulators and two high efficiency buck converters, a comparator, a reset and an I2C serial interface to program one buck and one regulator output voltages as well as power on timing control for complete flexibility.
The linear charger integrates LDO, MOSFET pass element, and thermal-regulation circuitry. The proprietary thermal-regulation circuitry limits the die temperature when fast charging or while exposed to high ambient temperatures, allowing maximum charging current without damaging the IC.
The two step-down converters are optimized for small size inductor and high efficiency applications. They utilize a proprietary hysteretic PWM control scheme that switches with nearly fixed frequency and is adjustable, allowing the customer to trade some efficiency for smaller external component, as desired. The output current is guaranteed up to 600mA, while quiescent current is a low 40μA (typ).
The LDO linear regulators provide high power supply rejection rate and have only 45μVRMS of output noises for 100Hz to 10kHz frequency range to power noise sensitive RF sections.
The RT9945 is available in WQFN-40L 5x5 package.
Applications
- GPS and PND
- PDA and Smart Phones
- Handheld Devices