AXP221

The AXP221 is the PMIC (Power Management IC) used by A31 SoCs and developed by X-Powers, a sister company of Allwinner.

Overview
AXP221 is a highly integrated PMIC targeted at single cell Li-battery (Li-ion or Li-polymer) applications that require multi-channel power conversion outputs. It provides an easy and flexible power management solution for multi-core processors to meet the increasingly complex and accurate requirements of power control.

AXP221 comes with an adaptive USB3.0-compatible Flash Charger that supports up to 94% efficiency and 2.2A charge current. It also provides 21 power output channels (including 5-CH DC-DC, with efficiency up to 95%). To ensure the security and stability of the power system, AXP221 provides multiple-channel 12-bit ADC for voltage/current/temperature monitoring and integrates protection circuits such as OVP, UVP, OTP, and OCP. Moreover, AXP221 integrates a unique E-Gauge™ system which simplifies battery power measurement.

Importantly, AXP221 also Featuress an IPS™ (Intelligent Power Select) circuit that transparently selects power path among USB, external adaptor, Li-battery, and system load, allowing the system to function normally when only running on external input power and not the battery.

AXP221 is available in 8mm x 8mm x 0.75mm 68-pin QFN package.

Features

 * IPS™
 * Input voltage range: 2.9V~6.3V (AMR: -0.3V~11V)
 * Configurable IPS™ system
 * Adaptive USB/AC adaptor voltage/current limit (4.4V/900mA/500mA)


 * Buck DC-DC Converters (5-CH)
 * DC-DC1: 1.6V~3.4V adjustable, 100mV/step, load current up to 1.4A
 * DC-DC2: 0.6V~1.54V adjustable, 20mV/step, load current up to 2.5A, supports VRC (Voltage Ramp Control)
 * DC-DC3: 0.6V-1.86V adjustable, 20mV/step, load current up to 2.5A
 * DC-DC4: 0.6V-1.54V adjustable, 20mV/step, load current up to 0.6A
 * DC-DC5: 1.0V-2.55V adjustable, 50mV/step, load current up to 2A


 * System Management
 * Support soft reset and hard reset
 * Support soft shutdown and hard shutdown
 * Support external wakeup triggers
 * Support PWROK for system rest or shutdown indication
 * External power detection (insert/remove/drive strength deficiency)
 * All output voltage support software boot
 * Over/Under-voltage protection (OVP/UVP)
 * Over-current protection (OCP)
 * Over-temperature protection (OTP)


 * E-Gauge™ System
 * Highly accurate gauge system with dual modes
 * Easy Mode: highly adaptive to different powers
 * Exact Mode: highly accurate data is provided for specific power
 * Provide rich power information, such as instantaneous power consumption (mA or mW), remaining power (% or mA), charge status (%), remaining power life, charge time, etc
 * Low power warning and low power protection
 * Provide die temperature


 * High Integration
 * Highly accurate (0.5%) reference voltage
 * Integrates MOSFET


 * Flash Charger
 * Integrated MOSFET charge current up to 2.2A
 * Battery temperature monitor
 * Fully supports USB charge
 * High charge accuracy, ±0.5% accuracy
 * Supports 4.1V/4.2V/4.22V/4.24V battery
 * Automatic charge control
 * Supports LED to indicate charge status
 * Automatic charge current adjustment based on system load


 * LDOs (14-CH)
 * RTC_VCC: 30mA, always valid
 * ALDO1/2: low noise LDO, 0.7V~3.3V adjustable, 100mV/step, load current up to 300mA
 * ALDO3: low noise LDO, 0.7V~3.3V adjustable, 100mV/step, load current up to 200mA
 * LDOIO0/LDOIO1: low noise LDO, 0.7V~3.3V adjustable, 100mV/step, load current up to 100mA
 * DLDO1/ ELDO1: 0.7~3.3V adjustable, 100mV/step, load current up to 400mA
 * DLDO2/ DLDO3/ ELDO2/ ELDO3: 0.7~3.3V adjustable, 100mV/step, load current up to 200mA
 * DLDO4: 0.7V~3.3V adjustable, 100mV/step, load current up to 100mA
 * DC5LDO: 0.7V~1.4V adjustable, 100mV/step, load current up to 200mA


 * Switch (2-CH)
 * DC1SW: internal resistance 100mOhm, power sourced from DCDC1
 * CHGLED:100mA sink strength, can be used to drive the motor and charging LED


 * Host Interface
 * P2WI (Push-Pull Two Wire Interface) for host communication
 * Configurable interrupt management
 * Flexible pin function configuration: 2 GPIOs can be set as IO or LDO, etc
 * Integrated timer
 * 12 groups of registers for system shutdown data storage

Regulators
The AXP221 features 5 DC-DC step-down (buck) converters, 14 linear regulators (5 of which are low-noise), and 2 switches. The DC-DC converters operate in automatic (PFM + PWM) or PWM mode, controllable via reg 80h, at a default frequency of 3 MHz. The frequency is controlled via reg 37h. It also supports spread spectrum.

Interrupts
This section corresponds to section 9.8 in the datasheet.

The AXP221 pulls the IRQ pin low to signal an interrupt to the host, and stores the interrupt status in the interrupt status registers (48h ~ 4Ch). Writing 1 to the corresponding bit clears the interrupt. When there are no interrupts, the IRQ pin is pulled up (by an external 51KΩ resistor). Each interrupt can be masked via the interrupt control registers (40h ~ 44h).

REG 31h: Wake-up control and VOFF Shutdown voltage setting
Default value: 03H

REG 32h: Shutdown control, battery detection and CHGLED pin control
Default value: 43h

REG 33h: Charge control 1
Default value: C6H

REG 34h: Charge control 2
Default value: 45h

REG 35h: Charge control 3
Default value: 0Eh

REG 36h: PEK button parameters
Default value: 5Dh

REG 38h: VLTF-charge Battery charging low temperature threshold
Default value: A5h

REG 39H: VHTF-charge Battery charging high temperature threshold
Default value: 1Fh

REG 3Ch: VLTF-charge Battery discharging low temperature threshold
Default value: FCh

REG 3DH: VHTF-charge Battery discharging high temperature threshold
Default value: 16h

REG 8Ah: Timer control
Default value: 00h

REG 8Ch: PWREN control 1
Default value: 00h

REG 8Dh: PWREN control 2
Default value: 00h

REG 8Fh: Thermal protection and misc. control
Default value: 01h

REG 04-0Fh: Data storage
As long as power exists, this data will be kept, not affected by system power off.

REG 10h: Regulator output control
Default value: XXH

REG 12h: Regulator output control
Default value: XXH

REG 13h: Regulator output control
Default value: 01H

Reg 37h: DC-DC operating frequency
Default value: 08h

REG 80h: DC-DC operation mode
Default value: 80H

Interrupts
See Interrupts section.

REG 90H: GPIO0 function control
Default value: 07h

REG 91h: LDOIO0 voltage control
Default value: 1Fh

REG 92H: GPIO1 function control
Default value: 07h

REG 93h: LDOIO1 voltage control
Default value: 1Fh

ADC
First register is high 8 bits, second is lower 4 (lower 5 for battery current).

REG 82H: ADC Enable
Default value: E0h

REG 84h: ADC sampling rate, TS pin control
Default value: 32h

REG B8h: Fuel Gauge Control
Default value: C0h

REG B9h: Battery Charge Reading
Default value: 64h

REG E0h: Battery Capacity Setting 1
Default value: 64h

REG E1h: Battery Capacity Setting 1
Default value: 64h

Battery capacity = value * 1.456mAh

REG E6h: Battery Low Warning Threshold Setting 1
Default value: A0h

Spec Sheets
AXP221 Datasheet v1.2 (PDF, 52 pages, 2013-03-26)