mm912f634 Freescale Semiconductor, Inc, mm912f634 Datasheet - Page 61

• Manufacturer Part Number: mm912f634
• Description: Mm912f634 - Integrated S12 Based Relay Driver With Lin
• Manufacturer: Freescale Semiconductor, Inc

Functional Description and Application Information
To avoid any critical behavior, it is essential to have the MCU Power On Reset (POR) active when the analog die reset
(RESET_A) is not fully active. As the RESET_A circuity is supplied by VDDX, VDD needs to be below the POR threshold when
VDDX is to low to guarantee RESET_A active (3;6). This is achieved with the following implementation.
Power Up:
Power Down:
Freescale Semiconductor
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The VDD regulator is enabled after VDDX has reached the V
Once VDD reaches V
Once VDDX has reached the V
pulled down to discharge any VDD capacitance (5). RESET_A is activated as well.
The active discharge guarantees VDD to be below POR level before VDDX discharges below critical level for the reset
circuity.
Range (not to scale)
Normal Operating
RESET_A
V
V
LBI
POR_MCU
V
V
V
/ V
POR_A
V
V
ROVX
LVRX
ROX
LVR
5V
LVI
LRV
, the RESET_A is released (2).
MCU_POR
VSUP
LVRX
Figure 18. Power Up / Down Sequence
threshold (4), the VDD regulator is disabled and the regulator output is actively
1
3
2
VDDX
LVRX
threshold (1).
VDD
4
5
6
MCU_POR
Power Supply
MM912F634
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