MCF51EM256CLL Freescale Semiconductor, MCF51EM256CLL Datasheet - Page 514

• Manufacturer Part Number: MCF51EM256CLL
• Description: IC MCU 32BIT 256KB FLASH 100LQFP
• Manufacturer: Freescale Semiconductor
• Series: MCF51EMr

Specifications of MCF51EM256CLL

• Core Processor: Coldfire V1
• Core Size: 32-Bit
• Speed: 50MHz
• Connectivity: I²C, SCI, SPI
• Peripherals: LCD, LVD, PWM, WDT
• Number Of I /o: 63
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Data Converters: A/D 16x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LQFP
• Processor Series: MCF51EM
• Core: ColdFire V1
• Data Bus Width: 32 bit
• Data Ram Size: 16 KB
• Interface Type: RS-232, LIN
• Maximum Clock Frequency: 50 MHz
• Number Of Timers: 3
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Development Tools By Supplier: DEMOEM
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Voltage Reference (VREF)
23.2.2
The VREF status and control register contains the control bits used to enable the internal voltage reference
and select the buffer mode to be used.
23.3
The Voltage Reference is a bandgap buffer system. Unity gain amplifiers are used.
The Voltage Reference can be used in two main cases. It can be used as a reference to analog peripherals
such as an ADC channel or analog comparator input. For this case, the low-power buffer can be used.
When the tight-regulation buffer is enabled, VREFO can be used both internally and externally.
Table 23-5
23-4
VREFEN MODE[1:0]
Register address: Base + 0x01
0
1
1
1
1
Reset:
Functional Description
W
R
shows all possible functional configurations of the Voltage Reference.
VREF Status and Control Register (VREFSC)
MCF51EM256 Series ColdFire Integrated Microcontroller Reference Manual, Rev. 8
MODE[1:0]
VREFEN
VREFST
00
01
10
11
X
Field
1:0
VREFEN
7
2
7
0
Figure 23-3. Voltage Reference Control Register (VREFSC)
Table 23-5. Voltage Reference Functional Configurations
Voltage Reference Disabled
Voltage Reference Enabled, Bandgap on
only
Voltage Reference Enabled, Low-Power
buffer on
Voltage Reference Enabled,
Tight-Regulation buffer on
Voltage Reference Disabled
Table 23-4. VREFSC Register Field Descriptions
Internal Voltage Reference Enable — This bit is used to enable the
Voltage Reference module.
0 the Voltage Reference module is disabled
1 the Voltage Reference module is enabled
Internal Voltage Reference Stable — This bit indicates that the Voltage
Reference module has completed its startup and stabilization.
0 Voltage Reference module is disabled or not stable
1 Voltage Reference module is stable
Mode selection — These bits are used to select the modes of operation for
the Voltage Reference module.
00 Bandgap on only, for stabilization and startup
01 Low-power buffer enabled
10 Tight-regulation buffer enabled
11 RESERVED
6
0
0
Configuration
Freescale Semiconductor
5
0
0
4
0
0
Description
Off
Startup and Standby
Can be used for internal peripherals only and
VREFO pin should not be loaded
Can be used both internally and externally. A
100nF capacitor is required on VREFO and
10mA max drive strength is allowed.
RESERVED
3
0
0
VREFST
2
0
Functionality
1
0
MODE
0
0