AN2201 Freescale Semiconductor / Motorola, AN2201 Datasheet - Page 5

• Manufacturer Part Number: AN2201
• Description: Low Battery Cranking Pulse in Automotive Applications
• Manufacturer: Freescale Semiconductor / Motorola

MOTOROLA
NOTE:
Low Voltage detect
The MC33389 SBC offers additional advantages, such as the integrated CAN
physical interface, a second MCU power supply, an external watchdog
functionality and high voltage key wake up ports. This is not shown here.
Please refer to the data book of the SBC MC33389 for detailed information.
Table 1
Low Battery Cranking Pulse in Automotive Applications
2 Options for early warning source:
Use VBat or VBat1 ?
Source
Freescale Semiconductor, Inc.
VBat1
VBat1
VBat
VBat
For More Information On This Product,
suggests different ways to create early warning options.
Go to: www.freescale.com
VBat
ECU
Connection
HCS12 ATD
HCS12 ATD
SBC
SBC
2 Options for early warning connection:
Use analog input from MCU or Wake up Pin from SBC ?
Table 1 Early Warning Options
VBat1
required to detect early warning, more effort required
L0 wake up
therefore usable when MCU is in STOP mode, but
spikes on VBat, also problems with protection of
May give many early warning interrupts due to
May give many early warning interrupts due to
to detect early warning when MCU is in STOP
Higher measurement accuracy, but SW effort
Causes interrupt when early warning occurs,
SBC
ATD input (reverse polarity, over voltage)
Figure 4
Vcc1
less accuracy for measurement
4
spikes on VBat
Reset
IRQ
SPI
Vdd
Remarks
A/D
STAR12
AN2201/D
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