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Current
mode
Battery
Voltage
HF
nIGNITION
EXTINT
KBR0
EXT_PWR
_SENSE
Power down
New mode
X
X
X
1
X
<0.5V
normal
OFF
X
X
X
X
0
X
X
emergency
OFF
X
X
X
X
1
1
<0.5V
normal
OFF
active
<4.0V
X
X
1
0
>1.2V
normal
restricted
active
<4.0V
no
X
1
1
>1.2V
normal
charge
active
<4.0V
yes
>2.5V
1
1
X
normal
OFF
active
<4.0V
yes
<0.5V
1
1
>1.2V
normal
charge
active
<4.0V
yes
>2.5V
1
0
X
normal
OFF
active
X
no
X
1
1
>1.2V
normal
charge
active
X
yes
<0.5V
1
1
>1.2V
normal
charge
active
X
yes
>2.5V
1
1
X
normal
OFF
active
X
yes
>2.5V
1
0
>1.2V
normal
OFF
active
X
X
X
1
0
<0.5V
normal
OFF
9.4
PowerManagement
The Power supply circuit needs to supply regulated power to the base-band parts, control battery charging and
monitor battery usage.
The power managementcircuithas three main functions:
1 Voltage regulators
2 Battery charging circuit
3 Power Fail detection
9.4.1 Power ManagementCircuit
In order to reduce the size and weight of the phone 4 NiMH cells have been chosen as the main power source.
Battery operating Voltage range:
4.0V (minimum safe discharge)
6V
(maximum fully charged )
However during charging the voltage could rises as high as 8V and all circuitry connected to the battery must be
designed to operate up to this voltage.
The battery voltage must be stepped-up to power 5V SIM cards. This circuit also shows a Power-On-Reset (POR)
to hold the CPU in a reset state while the supply voltage and system clock stabilise.
Issue 1
Section 9
MCUK971001G8
Revision 0
9 - 4
Technical Guide
POWER SUPPLIES