MM912H634CV1AE Freescale Semiconductor, MM912H634CV1AE Datasheet - Page 61

• Manufacturer Part Number: MM912H634CV1AE
• Description: 64KS12 LIN2xLS/HS Isense
• Manufacturer: Freescale Semiconductor
• Series: -r

Specifications of MM912H634CV1AE

• Applications: Automotive
• Core Processor: HCS12
• Program Memory Type: FLASH (64 kB)
• Controller Series: HCS12
• Ram Size: 6K x 8
• Interface: LIN
• Number Of I /o: -
• Voltage - Supply: 5.5 V ~ 27 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP Exposed Pad
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

4.5.1
To supply the MCU die and minor additional loads two cascaded voltage regulators have been implemented, VDDX (5.0 V) and
VDD (2.5 V). External capacitors (CVDD) and (CVDDX) are required for proper regulation.
4.5.2
To guarantee safe power up and down behavior, special dependencies are implemented to prevent unwanted MCU execution.
Figure 18
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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•
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The VDD regulator is enabled after VDDX has reached the V
Once VDD reaches V
The MCU is also protected by the MCU_LVR.
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.
shows a standard power up and power down sequence.
Range (not to scale)
Voltage Regulators VDD (2.5 V) & VDDX (5.0 V)
Power Up Behavior / Power Down Behavior - I64
V
Normal Operating
LVRX
The behavior explained previously is essential for the MC9S12I64 MCU die used, as this
MCU does have an internal regulator stage, but the LVR function only active in normal
modeMC9S12I64.
The shutdown behavior should be considered when sizing the external capacitors C
C
VDDX
RESET_A
/ V
V
V
LBI
POR_MCU
LVR_MCU
for extended low voltage operation.
V
V
/ V
POR_A
V
V
ROVX
ROX
5V
LVR
LVI
LRV
, the RESET_A is released (2).
3
LVRX
VSUP
Figure 18. Power Up / Down Sequence
MM912_634 Advance Information, Rev. 4.0
threshold (4), the VDD regulator is disabled and the regulator output is actively
1
2
NOTE
VDDX
LVRX
threshold (1).
VDD
4
5
6
VDD
and
Power Supply
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