MCIMX286CVM4B Freescale Semiconductor, MCIMX286CVM4B Datasheet - Page 901

• Manufacturer Part Number: MCIMX286CVM4B
• Description: IC MPU I.MX286 289MAPBGA
• Manufacturer: Freescale Semiconductor
• Series: i.MX28r

Specifications of MCIMX286CVM4B

• Core Processor: ARM9
• Core Size: 32-Bit
• Speed: 454MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, MMC, SmartCard, SPI, SSI, UART/USART, USB OTG
• Peripherals: DMA, I²S, LCD, POR, PWM, WDT
• Program Memory Size: 128KB (32K x 32)
• Program Memory Type: Mask ROM
• Ram Size: 32K x 32
• Voltage - Supply (vcc/vdd): 1.25 V ~ 5.25 V
• Data Converters: A/D 17x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 289-LFBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Eeprom Size: -
• Lead Free Status / Rohs Status: Compliant

Chapter 11 Power Supply
In addition, the i.MX28 integrates a 4.2 V regulator which enables the DC-DC converter
to run off the power supplied by 5 V. This allows the DC-DC converter operation when 5
V is present and the battery is exhausted. In addition, the path can provide better power
consumption as compared to the other linear regulator generated supplies. A current limiter
is implemented in a series with the 4.2 V regulator and the battery supply. The intent is to
limit the Ibattery plus I4P2 to be less than Ilimit. The 4.2 V regulator has priority on the
current and will dynamically reduce the battery charge current in order to preserve the Ilimit
and the regulated 4.2 V.
It should also be noted that the VDD5V voltage can dynamically change as the product is
plugged into a USB port or other 5-V supply. The i.MX28 is programmable to provide a
variety of behaviors when the VDD5V supply becomes valid or invalid, as well as to support
operation through USB or external power.
11.3.1 USB Compliance Features
Upon connection of 5 V to the powered-down device, the linear regulators will automatically
power up the device. To meet USB inrush specifications, linear regulators have a current
limit which is <100 mA, nominally 50 mA, and is active by default. This current limit is
disabled in hardware after power-up, but can be re-enabled through the
HW_POWER_5VCTRL_ENABLE_ILIMIT by software. System designers must understand
that the current inrush limit during 5 V power-up places restrictions on application current
consumption until it is disabled. Specifically, after connection to 5V, if the system draws
more current than the current limit allows, the startup sequence does not complete and the
ROM code does not execute.
Further, USB Host implies that B-devices must draw very little current from 5 V. This
requirement can be met by setting HW_POWER_5VCTRL_ILIMIT_EQ_ZERO when the
Host application is active. The comparators required for Host capability can be enabled by
HW_POWER_5VCTRL_PWRUP_VBUS_CMPS. It is also possible to change the threshold
of the Vbus valid comparator using HW_POWER_5VCTRL_VBUSVALID_TRSH.
If very low power operation is required, as in USB suspend, then the circuits required to
elegantly switch to the DC-DC converter may have to be powered off. In those cases, the
system must fully power down after VDD5V becomes invalid. It can auto restart with the
DC-DC converter, if HW_RTC_PERSISTENT0_AUTO_RESTART is set.
i.MX28 Applications Processor Reference Manual, Rev. 1, 2010
Freescale Semiconductor, Inc.
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