Overview
The RK816B is a complex power management integrated circuit (PMIC) for multi-core
system applications powered by Li-ion polymer battery cell, or by a 5V input either form an
USB port or form an adapter. The RK816B can provide a complete power management solution
with very few external components.
The RK816B provides four configurable synchronous step-down converters, and six LDO
regulators. The device also contains a bi-directional charger, the power path management
function, and a battery fuel gauge. Power up/power down controller is configurable and can
support any customized power up/power down sequences (OTP based). A real time clock (RTC)
is also integrated to provide a 32KHz output buffer, and real time function. The RK816B
supports 32KHz clock generation based on a crystal oscillator.
The switch mode bi-directional charger, together with power path controller integrated in
RK816B, allows supplying power form the USB to the loads while it is charging the battery.
The charger provides functions such as input current limiting, input voltage limiting, constant
temperature charging, trickle current charging, constant current/constant voltage charging,
charging termination, dead battery charging, charging over time protection, charging over or
under temperature protection, etc. All these functions can be conveniently configured through
the I2C digital interface. When the RK816B is powered only by the battery, the bi-directional
charger can work on boost mode, it achieves OTG function by supplying power from the battery
to the USB.
The charger input current limiting can be set to maximum 2A to accommodate a power
adapter as the input supply. When the input current limiting is triggered, the power path
controller will distribute the input power in a way that loads have the higher priority than the
battery to take the input power. The difference between the input and output power will be
used to charge the battery. In a case that the output power required by the loads exceeds the
input power, the power path controller will automatically turn on the battery switch so that the
battery can supply extra power to the loads together with input supply.
A battery fuel gauge is also integrated in the RK816B. Using the proprietary algorithms
and the sensed battery current and voltage, the gauge can accurately calculate the battery
capacity based on the charging or discharging characteristics of the battery preloaded in the
system. The gauge then sends the battery capacity information to the processor through the
I2C interface.
The RK816B can dynamically adjust the output voltage of each DC-DC converter, as
required by the processor based on the processor’s operation status so as to maximize the
system efficiency. The output voltages of most channels can be configured through I2C
interface. The inputs of all channels have soft start function, which greatly reduces the inrush
current at the start up. The frequency compensations of all the control loops are implemented
internally to eliminate external compensation components. The 2MHz switching frequency
allows small size inductors to be used for buck converters. Also, as all the power switches are
integrated on chip, no external power switches and schottky diodes are needed, which reduces
the system cost significantly.
The RK816B is available in a QFN40 5mmx5mm package, with a 0.40mm pin pitch.

Feature
 Input range: 3.8V ~ 5.5V for USB input； 2.7V~4.5V for BAT input
 Switch mode bi-directional Li-ion battery charger providing charging current up to 2.4A,
2MHz switching frequency for charger and boost
 Power path controller with 4A current path
 Accurate battery fuel gauge
 Real time clock（RTC）
 Low standby current of less than 45uA (at 32KHz clock frequency)
 2MHz switching frequency for buck converters
 Fast transient response due to the current mode architecture
 Internal frequency compensation and soft start
 Programmable output voltage and power up/power down sequence through I2C interface
 Proprietary circuit architecture achieving high efficiency
 Internal discharge path in off state for bucks and LDOs (configurable through I2C interface)
 Power channels:
 CH1: Synchronous buck converter, 2A max
 CH 2: Synchronous buck converter, 2A max
 CH 3: Synchronous buck converter, 1A max
 CH 4: Synchronous buck converter, 1A max
 CH 5: Synchronous boost converter, 0.8A max
 CH 6, CH7, CH9, CH10, CH11: low drop out voltage regulator, 300mA max
 CH 8: low noise, high PSRR low drop out voltage regulator, 100mA max
 CH 12：OTG switch, 0.8A max
 Fixed and programmable power up/power down sequences
 package: 5mm x 5mm QFN40