WM8321: Integrated Power Management Subsystem
The WM8321 is an integrated power-management subsystem which provides a cost-effective, flexible, single-chip solution for power management. It is specifically targeted at the requirements of a range of low-power portable consumer products, but is suitable to any application with a multimedia processor. The WM8321 is designed to operate as a system PMIC supporting the ARM9™, ARM11™ and ARM Cortex-A™ processors, but is also capable of supporting the majority of application and mobile processors at the heart of a wide range of low-power consumer multimedia applications.
The start-up behaviour and configuration is fully programmable in an integrated OTP non-volatile memory. This highly flexible solution helps reduce time-to-market, as changing application requirements can be very easily accommodated in the OTP. The InstantConfigTM interface enables an external EEPROM to configure the WM8321.
The WM8321 power management subsystem comprises four programmable DC-DC converters and eleven LDO regulators (four of which are low-noise for supplying sensitive analogue subsystems). The integrated OTP bootstrap circuitry controls the start-up sequencing and voltages of the converters and regulators as well as the sequencing of system clocks.
The DC-DC converters deliver high performance and high efficiency across a wide range of operating conditions. They are optimised to support the high load current transients seen in modern processor core domains. DC-DC3 / DC-DC4 can be connected together and operated in 'dual' mode to support an increased current load of up to 1.6A
An on-chip regulator provides power for always-on PMIC functions such as register map and the RTC. The device provides autonomous backup battery switchover. A low-power LDO is included to support 'Alive' processor power domains external to the WM8321.
A 12-bit Auxiliary ADC supports a wide range of applications for internal as well as external analogue sampling, such as voltage detection and temperature measurement.
WM8321 includes a crystal oscillator and an internal RC oscillator to generate all clock signals for autonomous system start-up and processor clocking. A Secure Real‑time Clock (S-RTC) and alarm function is included, capable of waking up the system from low-power modes. A watchdog function is provided to ensure system integrity.
To maximise battery life, highly-granular power management enables each function in the WM8321 subsystem to be independently powered down through a control interface or alternatively through register and OTP-configurable GPIOs. The device offers a standby power consumption of <7uA, making it particularly suitable for portable applications.
- 2 x DC-DC synchronous buck converters (0.6V - 1.8V, 1.25A, DVS)
- 2 x DC-DC synchronous buck converters (0.85V - 3.4V, 1A)
- 1 x LDO regulator (0.9V - 3.3V, 300mA, 1W)
- 2 x LDO regulators (0.9V - 3.3V, 200mA, 1W)
- 3 x LDO regulators (0.9V - 3.3V, 100mA, 2W)
- 2 x Low-noise LDO regulators (1.0V - 3.5V, 200mA, 1W)
- 2 x Low-noise LDO regulators (1.0V - 3.5V, 150mA, 2W)
- 1 x 'Alive' regulator (0.8V – 1.55V, up to 25mA)
- I²C or SPI compatible primary control interface
- Comprehensive interrupt scheme
- Watchdog timer and system reset controlAutonomous power sequencing and fault detection
- OTP memory bootstrap configuration function
- Auxiliary ADC for multi-function analogue measurement
- 128-bit pseudo-random unique ID
- Secure Real-Time Clock with wake-up alarm
- 12 x configurable multi-function (GPIO) pins
- Comprehensive clocking scheme: low-power 32kHz RTC crystal oscillator, GPIO clock output and 4MHz RC clock for power management
- System LED outputs indicating device power state, and fault status
- 8 x 8 x 0.85mm, 81-lead QFN package
Ordering & Samples
- WM831x/2x - Programming the OTP, Rev 1.1
- WM831x/2x - InstantConfig EEPROM (ICE), Rev 1.0
- WM8321-Recommended External Components, Rev 1.3
- Recommendations on Soldering a Dual Row QFN Package to a PCB, Rev 1.0
- WM831x and WM832x Converter Operating Modes, Rev 1.1
- WM832x Customer Evaluation System Set-up Guide, Rev 1.0
- How to Connect WM832x to an External Battery Charger, Rev 1.0
- Decoupling and Layout Methodology for Wolfson DACs, ADCs and CODECs, Rev 1.1