User's Manual

Table Of Contents
MC46 Hardware Interface Description
DRAFT
MC46_HD_V02.8xb Page 28 of 98 21.08.2003
3.3.1.2 Timing of the ignition process
When designing your application platform take into account that powering up MC46 requires
the following steps.
· The ignition line cannot be operated until V
BATT+
passes the level of 3.0V.
· The ignition line shall not be operated earlier than 10ms after the last falling edge of VDD.
· 10ms after V
BATT+
has reached 3.0V the ignition line can be switched low. The duration of
the falling edge must not exceed 1ms.
· Another 100ms are required to power up the module.
· Ensure that V
BATT+
does not fall below 3.0V while the ignition line is driven. Otherwise the
module cannot be activated.
· If the VDDLP line is fed from an external power supply as explained in Chapter 3.8, the
/IGT line is HiZ before the rising edge of BATT+.
Figure 4: Timing of power-on process if VDDLP is not used
Figure 5: Timing of power-on process if VDDLP is fed from external source
3.0V
0V
BATT+
min. 100ms
max. 1ms
10ms
/IGT
HiZ
HiZ
3.0V
0V
min. 100ms
max. 1ms
10ms
HiZ
HiZ
BATT+
/IGT