C8051F540-TB Silicon Laboratories Inc, C8051F540-TB Datasheet - Page 72

• Manufacturer Part Number: C8051F540-TB
• Description: BOARD PROTOTYPE W/C8051F540
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F540-TB

• Contents: Board
• Processor To Be Evaluated: C8051F54x
• Processor Series: C8051F54x
• Interface Type: USB
• Operating Supply Voltage: 5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: C8051F54x
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1672

C8051F54x
9. Voltage Regulator (REG0)
C8051F54x devices include an on-chip low dropout voltage regulator (REG0). The input to REG0 at the
V
enabled, the output of REG0 appears on the V
power external devices. On reset, REG0 is enabled and can be disabled by software.
The Voltage regulator can generate an interrupt (if enabled by EREG0, EIE2.0) that is triggered whenever
the V
flag and the recommended procedure to use it is as follows:
1. Wait enough time to ensure the V
2. Enable the dropout interrupt (EREG0, EIE2.0) and select the proper priority (PREG0, EIP2.0)
3. If triggered, inside the interrupt disable it (clear EREG0, EIE2.0), execute all procedures necessary to
4. In the main application, now running in the safe mode, regularly check the DROPOUT bit (REG0CN.0).
The input (V
tor (4.7 µF + 0.1 µF) to ground as shown in Figure 9.1 below. This capacitor will eliminate power spikes
and provide any immediate power required by the microcontroller. The settling time associated with the
voltage regulator is shown in Table 6.8 on page 54.
If the internal voltage regulator is not used, the V
72
REGIN
protect your application (put it in a safe mode and leave the interrupt now disabled).
Once it is cleared by the regulator hardware, the application can enable the interrupt again (EREG0,
EIE1.6) and return to the normal mode operation.
REGIN
pin can be as high as 5.25 V. The output can be selected by software to 2.1 V or 2.6 V. When
input voltage drops below the dropout threshold voltage. This dropout interrupt has no pending
REGIN
Figure 9.1. External Capacitors for Voltage Regulator Input/Output—
) and output (V
REG0
V
DD
DD
) of the voltage regulator should both be bypassed with a large capaci-
4.7 µF
4.7 µF
REGIN
Regulator Enabled
input voltage is stable
DD
REGIN
Rev. 1.1
pin, powers the microcontroller core, and can be used to
input should be tied to V
.1 µF
.1 µF
V
V
DD
REGIN
DD
, as shown in Figure 9.2.