Company Confidential
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Copyright 2005© Siemens AG
Page
35
of
53
TD_Repair_L2.5_A70_A75_R1.0.pdf Release
1.0
9.1 Power Supply ASIC
The power supply ASIC will contain the following functions:
Powerdown-Mode
Sleep Mode
Trickle Charge Mode
Power on Reset
Digital state machine to control switch on and supervise the uC with a watchdog
Voltage regulator
Low power voltage regulator
Additional output ports
Voltage supervision
Temperature supervision with external and internal sensor
Battery charge control
TWI Interface (I2C interface)
Bandgap reference
Audio multiplexer
Audio amplifier stereo/mono
16 bit Sigma/Delta DAC with Clock recovery and I2S Interface
Power Supply Operating modes:
The
ASIC
can be used in different operating modes:
Mode Pin
Requirements
Description
Power down
mode with
minimum activity
ON/OFF
ON/OFF2
VDD_CHARGE
In power down mode the current consumption of the ASIC is
very low. The inputs for switch on conditions (Pin ON/OFF,
ON/OFF2,VDD_CHARGE), the LPREG, Bandgap reference,
and the POR cells are active. All other blocks are switched off,
so the battery is not discharged. This state is called “phone
off.
Start Up Mode
ON_OFF
ON_OFF2
Start Up Mode can be initiated by ON_OFF or ON_OFF2. In
this mode a sequential start-up of references (this includes the
reference buffer and the biasing cell), oscillator., voltage
supervision and regulators is controlled by digital part. In
failure case (undervoltage, overvoltage or time out of the µC
reaction)., the ASIC is shut down.
Full operating
mode
VDD_CHARGE
CHARGE_UC
All blocks are active. Trickle charge is switched off. The blocks
fast charge and charge monitor can be active only in this
mode. These modes will be activated with VDD_CHARGE or
CHARGE_UC. The name of this mode is “phone on” or “active
mode”. The border between the startup phase and the active
mode is the rising edge of the RESETN signal. This will allow
the uC to start working.
