User manual

 2004 Microchip Technology Inc. Preliminary DS41239A-page 49
PIC10F200/202/204/206
FIGURE 9-9: BROWN-OUT
PROTECTION CIRCUIT 3
9.9 Power-down Mode (Sleep)
A device may be powered down (Sleep) and later
powered up (wake-up from Sleep).
9.9.1 SLEEP
The Power-down mode is entered by executing a
SLEEP instruction.
If enabled, the Watchdog Timer will be cleared but
keeps running, the TO
bit (Status<4>) is set, the PD bit
(Status<3>) is cleared and the oscillator driver is turned
off. The I/O ports maintain the status they had before
the SLEEP instruction was executed (driving high,
driving low or high-impedance).
For lowest current consumption while powered down,
the T0CKI input should be at VDD or VSS and the GP3/
MCLR
/VPP pin must be at a logic high level if MCLR is
enabled.
9.9.2 WAKE-UP FROM SLEEP
The device can wake-up from Sleep through one of
the following events:
1. An external Reset input on GP3/MCLR
/VPP pin,
when configured as MCLR
.
2. A Watchdog Timer time-out Reset (if WDT was
enabled).
3. A change on input pin GP0, GP1 or GP3 when
wake-up on change is enabled.
4. A comparator output change has occurred when
wake-up on comparator change is enabled.
These events cause a device Reset. The TO
, PD
GPWUF and CWUF bits can be used to determine the
cause of device Reset. The TO
bit is cleared if a WDT
time-out occurred (and caused wake-up). The PD
bit,
which is set on power-up, is cleared when SLEEP is
invoked. The GPWUF bit indicates a change in state
while in Sleep at pins GP0, GP1 or GP3 (since the last
file or bit operation on GP port). The CWUF bit
indicates a change in the state while in Sleep of the
comparator output.
Note: A Reset generated by a WDT time-out
does not drive the MCLR
pin low.
Note: This Brown-out Protection circuit employs
Microchip Technology’s MCP809 micro-
controller supervisor. There are 7 different
trip point selections to accommodate 5V to
3V systems.
MCLR
PIC10F20X
VDD
VDD
VSS
RST
MCP809
VDD
Bypass
Capacitor
Note: Caution: Right before entering Sleep,
read the input pins. When in Sleep, wake-
up occurs when the values at the pins
change from the state they were in at the
last reading. If a wake-up on change
occurs and the pins are not read before re-
entering Sleep, a wake-up will occur
immediately even if no pins change while
in Sleep mode.
Note: The WDT is cleared when the device
wakes from Sleep, regardless of the wake-
up source.