MCIMX286CVM4B Freescale Semiconductor, MCIMX286CVM4B Datasheet - Page 2263

• 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

38.2 Operation
All channels of the LRADC share a common successive approximation style analog-to-digital
converter through a common analog mux front end (see
The touch-screen driver works for typical touch-screen impedances of 200–900 ohm and
for high impedance touch-panels with impedances in the 50-Kohm range.
The LRADC channels 0 and 6 have optional current source outputs to allow these channels
to be used with an external themistor (or an external diode) for temperature sensing. The
controls for these current sources are in HW_LRADC_CTRL2. The current source values
can be changed to allow significant temperature sensing range using a thermistor or to use
a diode for temperature sensing. The currents are derived using the on-chip 1% accurate
bandgap voltage reference and an optionally tuned on-chip poly resistor. The accuracy of
the current source is limited by the on-chip resistor, which should be 5% accurate and
optionally tuned for higher accuracy (with efuses). Most thermistors are no more than 5%
accurate, so this level of current source accuracy is acceptable for most applications. For
temperature sensing with higher accuracy, customers can use a 1% resistor divider from
VDDIO with the thermistor. In this case, the thermistor will be the dominant source of error.
38.2.1 External Temperature Sensing with a Diode
Using a diode instead of a thermistor for external temperature sensing can be cheaper and
provide greater temperature range for a given accuracy level. An inexpensive diode like a
1N4148 is connected between ground and either LRADC 0 or 6. Two voltage measurements
Freescale Semiconductor, Inc.
• The BATT pin has a built-in 4:1 voltage divider on its analog multiplexer input that is
• The Channel 15 5V input also has a built-in 4:1 divider on its input.
• The Channel 10 VDDIO input and the Channel 12 VDDA input have a built-in 2:1
• For input channels (other than BATT, 5V, or VDDIO) with signals larger than 1.85 V,
activated only in Li-Ion battery mode.
divider on their inputs. The maximum analog input voltage into the LRADC is 1.85 V.
the divide-by-two option should be set (HW_LRADC_CTRL2_DIVIDE_BY_TWO).
With the DIVIDE_BY_TWO option set, the maximum input voltage is VDDIO – 50mv.
The pad ESD protection limits the voltage on the
LRADC0-LRADC6 inputs to VDDIO. The BATT and 5V inputs
to the LRADC have built-in dividers to handle the higher voltages.
i.MX28 Applications Processor Reference Manual, Rev. 1, 2010
Chapter 38 Low-Resolution ADC (LRADC) and Touch-Screen Interface
Note
Figure
38-2).
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