Applicant: Motorola, INC
The VREF regulator incorporates 3 operating modes that are controlled by the AT+MVREF
command. These modes define the regulator operating state relative to the module's operating mode.
The following figure sows the VREF power-up timing.
In this mode the VREF regulator is disabled and its output drops to 0V, regardless of the module's
The Standby operating mode is the default mode when module powers on. In this mode VREF
follows the module's operating state.
When the module is in low power mode, Sleep mode, the VREF regulator is also in a low power
state. In this state the VREF regulated output is limited to providing only 1mA of current
maximum, while maintaining the 2.8V output level.
When module is in Idle mode, or wakes up temporarily from low power mode, the VREF regulator
returns to full operation, supplying up to 150 mA.
In this mode the VREF regulator is always fully active while module is operating, regardless of the
module operating mode.
The wakeup-out (WKUPO_N) signal is an active low output, which is designed to support a low
power mode feature in the host application. This signal is used by the module to indicate that it
requires to communicate with the host application through the serial interface, due to an incoming
call or data, or an unsolicited event.
The wakeup out mechanism, using the WKUPO_N signal, is controlled by 2 AT commands:
• ATS102 - Defines the delay time in milliseconds that the module will wait, after asserting the
WKUPO_N signal low, before sending data on the serial interface. This delay is required to
allow the application enough time to reactivate from low power mode and switch to normal
≤ 150 mA
20 Hz – 20 KHz
Motorola General Business Use
Page 33 of 36
C24 Hardware Interface Manual
FCC ID: IHDP56JE1