Power On/Off Operation; Turning The C24 On; Turning The C24 On Using On_N; On_N Power On Timing - Motorola 8900 - Blackberry Curve Cell Phone OEM Car Charger Developer's Manual

Power On/Off Operation

Power On/Off Operation
When the C24 power supply is stable above the minimum operating level and C24 is powered off,
only the internal RTC timer is active.
The C24 power on and off process includes two primary phases, which are indicated at the
interface connector by the hardware output signals RESET_N and CTS_N.
The RESET_N signal indicates whether C24 is powered on or off.
When this signal is enabled (low), C24 is powered-off. When it is disabled (high), C24 is
powered-on.
The CTS_N signal indicates the serial communications interface (UART) status. When this signal
is high, the C24 serial interface is disabled. When it is low, the serial interface is enabled, and C24
is ready to communicate.
Important:

Turning the C24 On

During a power on process C24 may toggle several interface signals, which are visible to the
application. These signals do not represent any valid state or data, and should be ignored by the
customer application until completed.

Turning the C24 On Using ON_N

The ON_N input signal is set high, by an internal pull-up resistor whenever a power supply is
applied to C24. Therefore, it is recommended to operate this signal using an open collector/drain
circuit connection.
Asserting the ON_N signal low for a minimum of 500 milliseconds (0.5 seconds) and a maximum
of 1.5 seconds will cause the C24 to turn-on.
Figure 2-2
Figure 2-2: ON_N Power On Timing
12
Do not operate the C24 out of its electrical or environmental limits. Refer to the
specifications chapter for details of these limits.
illustrates the power-on process using the ON_N signal.
C24 Module Hardware Description December 15, 2008