CP2400 SILABS [Silicon Laboratories], CP2400 Datasheet - Page 53

• Manufacturer Part Number: CP2400
• Description: 128/64 SEGMENT LCD DRIVER
• Manufacturer: SILABS [Silicon Laboratories]

9.5.
Shutdown mode is the lowest power mode for the CP2400/1/2/3. All device functionality is disabled in this mode
and a reset is required to wake up the device. This mode is typically used when the device is not needed for
prolonged periods of time.
From Normal Mode, the device can be placed in shutdown mode using the following procedure:
The device will not enter Shutdown if there are pending wake-up events, and the INT pin will remain asserted. To
ensure that the device has successfully entered the low power mode, the host processor should verify that there
are no pending wake-up events prior to placing the device in Shutdown Mode and that the INT pin remains de-
asserted for 100 µs after placing the device in Shutdown Mode. If the INT pin is found to be asserted after the
device has been placed in Shutdown, the device should be reset and placed in shutdown again. It is essential that
all ULP Port Mask bits be set to logic 0 before the device is placed in Shutdown in order to prevent the possibility of
a partial wake-up due to a Port Match event. The Port Match, SmaRTClock Alarm, and SmaRTClock Oscillator Fail
interrupts should always be enabled any time the device is placed in Shutdown mode.
Note: The Port I/O state and configuration settings are preserved as long as the device is in Shutdown. Upon reset, all Port I/O
state and configuration settings will reset, making all Port I/O digital inputs with weak pull-ups enabled. They will remain
in this state until the host controller re-initializes the Port I/O state and configuration registers.
Shutdown Mode
1. Set INT0EN:INT1EN to 0x1900. This enables the SmaRTClock Fail, SmaRTClock Alarm, and Port
2. Ensure that all ULP Port Mask bits are set to logic 0 by writing 1 to ULPRST (ULPCN.1).
3. Configure the bandgap for Shutdown Mode by writing 0x80 to MSCF.
4. Drive the PWR or NSS pin LOW.
5. Set the RTCDIS (ULPCN.4) and the ULPEN (ULPCN.1) bit to logic 1.
6. Drive the PWR or NSS pin HIGH.
Match interrupts and disables all others.
Rev. 1.0
CP2400/1/2/3
53